Fourth International Orca Symposium and Workshop - CEBC - CNRS

Fourth International Orca Symposium 

and Workshop 

September 23-28, 2002 

CEBC-CNRS, France 

© Frédérick Presle 

FOURTH INTERNATIONAL ORCA SYMPOSIUM AND WORKSHOPS 

SEPTEMBER 23-28 2002, CEBC-CNRS, France 

1

Orca Symposium & Workshop 

CEBC-CNRS 

79 360 Villiers en Bois 

France 

Tel 00 (33) (0) 5 49 09 78 39 

Fax 00 (33) (0) 5 49 09 65 26 

Organising Committee:Lance Barrett-Lennard (barrett@zoology.ubc.ca) 

John Ford (ford@zoology.ubc.ca) 

Christophe Guinet (guinet@cebc.cnrs.fr) 

Tiu Similä (iolaire@online.no) 

Fernando Ugarte (fernando_ugarte@hotmail.com) 

Contents: 

Workshops 4 

Oral And Poster Presentations: 32 

Social determinants of population structure in killer whales: insights from association patterns, 

genetics and acoustics. 32 

Killer Whales At Marion Island, Southern Ocean 35 

Behavior and Ecology of Killer Whales in Monterey Bay, California 40 

Killer Whales (Orcinus orca) of Alaska: Gulf of Alaska to the Bering Sea. 45 

A REVIEW of Killer Whales (Orcinus orca) in Brazilian waters 46 

Sightings of killer whales off the Antarctic Peninsula from 1997/98 to 2001/02 50 

Click characteristics of killer whales feeding on Norwegian spring-spawning herring 54 

The BC Cetacean Sightings Network: working with the public to determine year-round 

distribution patterns 57 

Vocal Behaviour of Transient Killer Whales: Food Calling or Constrained Communication 59 

Mirror Image Processing in Killer Whales (Orcinus orca) 63 

Scaling Issues In Predator-Prey Interactions: Killer Whale Underwater Tail-Slaps 64 

Analysis of the discrete calls of killer whales from the Avacha Gulf of Kamchatka, Far East 

Russia 65 

Killer whales (Orcinus orca) in shetland waters 68 

Reassessing The Social Organization Of Resident Killer Whales In British Columbia 72 

Behavioural and acoustic differences among belugas (Delphinapterus leucas) summer herds in 

the St. Lawrence estuary (Québec, Canada). 75 

Current Knowledge of Killer Whales in the Mexican Pacific 76 

Analysis of photo-identification data to make inferences about cetacean populations 77 

Assessing The Impacts Of Killer Whale Predation On Steller Sea Lions In Western Alaska 81 

World-wide genetic diversity in the killer whale (Orcinus orca); implications for demographic 

history. 83 

Socioecology of killer whales (Orcinus orca) in Northern Patagonia 84 

Cooperative Hunting And Prey Handling Of Killer Whales In Punta Norte, Patagonia, 

Argentina 85 

Killer whale (Orcinus orca) sightings in Alaska: Preliminary results from mariner survey data 

86 

Bioenergetic Changes From 1986 To 2002 In Southern Resident Killer Whales, Orcinus Orca 

88 

Surface intervals of an adult male killer whale in norway 89 

Predatory Activity Of A Single Killer Whale, Orcinus Orca, At A Steller Sea Lion, Eumetopias 

Jubatus, Rookery In Alaska 92 



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Anatomy of a Long-term Study: Population Ecology of Killer Whales in Prince William 

Sound and Kenai Fjords, Alaska 1983-2002. 95 

Killer Whale Population Biology and Feeding Ecology in southeastern Alaska. 98 

unraveling the influence of social structure and prey type on vocal communication in killer 

whales 105 

O. orca abundance, distribution, seasonal presence, predation and strandings in the waters 

around Kamchatka and the Kommander Islands: An assessment based on reported sightings 

1992-2000 106 

Killer whales (Orcinus orca) in Australian territorial and surrounding waters – are they 

secure ? 109 

Life history and decline of killer whales in crozet archipelago, southern indian ocean 119 

Life history and population dynamics of resident killer whales in Alaska 117 

Monitoring Whale Watching Activity In International Waters 120 

Life history and decline of killer whales in Crozet Archipelago, southern Indian Ocean 121 

Toxic chemical pollution and Pacific killer whales (Orcinus orca) 126 

The Biology and Status of an Endangered Transient Killer Whale Population in Prince William 

Sound, Alaska 131 

Matched Vocal Exchanges Of Shared Stereotyped Calls In Free-Ranging Resident Killer 

Whales 133 

Satellite Tracking Study Of Movements And Diving Behaviour Of Killer Whales In The 

Norwegian Sea 134 

Clicks, calls and underwater tail-slaps; sounds of norwegian killer whales. 136 

Aerial vocalisations of killer whales temporarily captured in northern norway. 137 

Interactions Between Killer Whales (Orcinus Orca) And Red Tuna (Thunnus Thynnus) Fishery 

In The Strait Of Gibraltar 138 

Observations Of Killer Whales During The Fall, Winter And Spring In Southeastern Alaska 

1980-2002 146 

What is the favourite prey ? Foraging ecology of killer whales at avacha gulf, russian far east. 

151 

Population Viability Analysis for the Southern Resident Population of Killer Whales 152 

Predation Behavior Of Transient Killer Whales In Monterey Bay, California 156 

Whistles and variable calls as close-range acoustic signals in wild killer whales off vancouver 

island, british columbia 160 

A Review Of Short- And Long-Term Effects Of Whale Watching On Killer Whales In British 

Columbia 165 

Associations and group size of killer whales in Kvæfjord, Norway, during October-November 

1997 168 

Norwegian killer whales feed on small herring schools close to the surface 174 

Can Routine Data Collection Benefit Killer Whale Research? 178 

New Zealand orca 183 

Pigmentation As An Indicative Feature For Populations Of Killer Whales 186 

First photo-identification matches for papua new guinea killer whales. 189 

Changes in call use in a resident orca-matriline with a new-born calf 190 

Spatial Modelling Of Antarctic Killer Whale Abundance And Distribution 192 

A Bioenergetic Model For Estimating The Food Requirements Of The Killer Whale (Orcinus 

Orca) 196 

Why do some killer whales talk so much? 199 

Authors index 207 



3

Workshops 

FORAGING ECOLOGY 

CONSERVATION 

ACOUSTIC 

POPULATION DYNAMICS, POPULATION STRUCTURE AND LIFE-HISTORY 



4

KILLER WHALE WORKSHOP - FORAGING ECOLOGY 

Participants: 

Nancy Black 

Yves Cherel 

Luciano Dalla Rosa 

Paolo Domenici 

Graeme Ellis 

Christophe Guinet 

Dena Matkin 

Eva Saulitis 

Karina Tarasyan 

Alisa Schulman-Janiger 

Tiu Similä 

Jan Straley 

Richard Ternullo 

Victoria Turner 

Ingrid Visser 

Arliss Winship 

INTRODUCTION 

The workshop participants discussed the following topics 

- How generalist/specialist are killer whale populations in their choice of prey? How 

flexible are killer whales to changes in prey abundance? 

- How can we identify the prey species of killer whales? 

- How does the choice of prey affect the behaviour and habitat use of killer whales ? 

- Recommendations for future work 

HOW GENERALIST/SPECIALIST ARE KILLER WHALES? 

In the previous Orca Symposium in 1990 one of the main topics of discussions was the 

presence of two different types of killer whales in the coastal waters of eastern Pacific Ocean 

(from Alaska to California): the fish feeding residents and the marine mammal feeding 

transients. The difference in diet affects profoundly the behaviour, occurrence pattern, social 

organisation and acoustics of the two populations. The presence of two different types of 

killer whales within the same geographic area received much attention, and it was questioned 

if a similar situation existed elsewhere in the world and also if any killer whale populations 

have a more ”mixed” diet containing both marine mammals and fish. At that time there was 

evidence for the existence of separate marine mammal and fish feeding populations in the 

Antarctic waters, but information from other regions was considered preliminary. 

Since 1990, a third type of killer whale, ”offshore killer whales” have been described in 

the Northeastern Pacific. The offshore killer whales feed on fish and severe tooth wear 

suggests that an abrasive food source, such as elasmobranchs might be part of their diet. The 

offshore killer whales have not bee observed to mix with the residents and therefore it is 

suggested that sympatric, fish-feeding populations exist in these waters as well. In a recently 

started study in Kamchatka, Russia, the prey type of killer whales during summer season has 

been identified as fish (herring, mackerel and salmon). In Gibraltar Strait killer whales are 

feeding on tuna, also from the longlines used in the local fishery. Interaction with longline 

fishery has also been documented from the Crozet Islands, New Zealand and Brazil. In the 

Northeast Atlantic killer whales feed on herring stocks both in Icelandic and Norwegian 



5

coastal waters. A satellite tracking study conducted in Norway indicates that the killer whales 

follow the yearly migration route of Norwegian spring-spawning herring. However, visual 

observations were not made of the killer whales during summer months and it is possible that 

the killer whales were preying on one of the predator species (fish, marine mammals) that 

follow herring to their feeding grounds during summer. 

One of the most important findings since the previous Orca Symposium has been the 

documentation of a mixed diet (i.e fish and marine mammals) for killer whales in the coastal 

waters of Argentina, Brazil, the Crozet Islands, New Zealand and Norway (for one group 

only). In all these areas further observations are needed for better documentation of how 

common a mixed diet is and to investigate the possibility of some killer whales specialising in 

marine mammals. 

In short, it is clear that there are both killer whales with very specialised diet and killer 

whales with a more varied diet. In addition, regardless of the degree of 

specialisation/generalisation in the population, group specific specialisations have been 

documented in many of the populations studied. The behaviour, especially the acoustic 

behaviour, of the populations with a mixed diet should be one of the focuses of future studies 

(more details in behaviour chapter). 

It should also be stressed that it is not sufficient to divide the prey of killer whales into 

just these two broad categories; fish and marine mammals. Killer whales do also feed on other 

type of prey (for example pelagic sharks). In addition, the behaviour and sensory abilities 

differ greatly among marine mammal and fish species. 

One of the obvious benefits of specialising on certain type of prey is in being able to 

develop and refine foraging techniques in a way that makes these populations very efficient 

hunters. However, the cost of being a specialist might be that the population is not flexible in 

adjusting to changes in prey abundance, ie. such populations are not likely to switch their prey 

type. 

The workshop participants suggested that predictability and abundance of prey could 

explain why some killer whales are specialised in their choice of prey while other populations 

are not. It was suggested that modelling prey abundance and occurrence for areas where there 

are specialists and areas where there are generalists might give us a better understanding of 

the underlying mechanisms. 

How to determine prey species? 

As the previous discussion shows, being able to identify killer whale prey species is 

important. In principle there are three different ways of studying the diet of killer whales; 

stomach content analysis of dead animals, observations of foraging killer whales and analysis 

of stable isotopes or fatty acids from biopsies. 

Identifying prey species through observing feeding killer whales can be very 

challenging. Identity of prey species is relatively easy to establish when feeding occurs close 

to the surface (eg. carousel feeding on schooling fish) or on the shore (eg. killer whales 

hunting on pinnipeds in Crozet and Patagonia). Observing killer whales feeding on fish or 

marine mammals below the surface is much more demanding. Underwater videocameras 



6

(including crittercams) and high-frequency sonars can be helpful, but the use videocamera is 

restricted by visibility and sonar images do not necessarily allow for identifying prey species. 

Recent developments including a TDR (Time-depth recorder) which combines dive data to 

digital images of surroundings (including prey items) might prove useful. Developing 

observational skills is also important as was exemplified by how many years it took before 

marine mammal kills by transient killer whales in British Columbia were recognized. 

“Researcher exchange” has also proven very useful in several studies. Using same-observer 

skills in documenting the behaviour of different populations is recommended for several 

reasons; especially in new studies the presence of a skilled observer can be vital in identifying 

feeding behaviours and prey types and the use of “same pair of eyes” is also a way to make 

sure that the results from different studies are comparable. 

The use of a fine-mesh dipnet in collecting prey remains (fish scales, parts of marine 

mammals) among feeding killer whales is strongly recommended. This technique has been 

very useful in documenting the diet of killer whales in British Columbia. 

Biopsies containing killer whale blubber can be used for fatty acid analyse which are 

useful at least for in identifying trophic level of prey species. Fatty acid analysis conducted on 

transient and resident killer whales showed that these populations feed on prey from different 

trophic levels. Such analyse could be useful in identifying the trophic level of prey in other 

killer whale populations as well. More difficult is the use of this technique in identifying 

possible changes in prey species (ie. switching from one fish species to another). For better 

understanding of how such changes can be studied by fatty acid profiles, an experimental 

study should be conducted on captive animals subjected to switch in their diet. It was stressed 

that any project collecting biopsy samples should make all possible effort to collect the 

samples in such a way that they can be used for different analysis; genetics, fatty acid profiles, 

toxic chemicals. 

Killer whale carcasses tend to sink, and therefore access to stomach contents is fairly 

limited. In addition, stomach content analysis is difficult to interpret given that the prey of the 

target species is taken simultaneously. Erosion of bones could be looked at to discern target 

prey of the killer whale (i.e. fish in stomachs of marine mammals and fish in stomachs of 

other fish, elephant seals with squid beaks in stomachs). 

How does choice of prey affect the foraging behaviour of killer whales? 

One of the main topics of the discussion in the workshop was how well killer whales are 

able to adjust their behaviour to feeding on different types of prey. In this context the 

populations feeding both on fish and marine mammals are of special interest. The studies 

conducted in Northeastern Pacific have clearly shown that the social and acoustic behaviour 

differs greatly between the marine mammal and fish feeding populations; silence is important 

when searching and hunting marine mammal prey while killer whales feeding on fish are 

vocal both while they are searching and feeding on fish. To date very little information exists 

on the acoustic behaviour of the killer whales which feed both on marine mammals and fish 

and future studies focusing on this are strongly recommended. One group of killer whales in 

the Monterey Bay area have been observed feeding on elasmobranchs and fish. When feeding 

on elasmobranchs the whales were in a small group and very silent, like transient killer 

whales while feeding on marine mammals. The group size was larger when these whales were 

feeding on fish, but it is not known if the whales are vocal when feeding on fish. 



7

Evidence for flexibility in vocal behaviour has been demonstrated for transients in 

Monterey Bay; the killer whales are silent while hunting small-sized marine mammal prey but 

are very vocal while hunting and feeding on grey whale calves. It is possible that the vocal 

activity increases to attract more whales to participate in the hunt for larger sized prey. 

Observations of transient killer whales in BC and Alaska also suggest that the transient killer 

whales which have been thought to occur in small groups may be living in larger social units 

that are in acoustic contact. They forage in small groups and start vocalising after kills to join 

for social behaviours. 

The group size of transients may vary depending on the size of prey. When feeding on 

harbour seals, the groups tend to be small. Sea lions are larger and also more dangerous for 

the killer whales to catch and therefore the group size is often larger when sea lions are 

caught. Although harbour porpoises, Dall’s porpoises and white-beaked dolphins are not very 

large, the transients need to operate in larger groups while hunting them since these small 

cetaceans are swift and able to evade predation unless pursued by several whales. 

The size of the prey can also be viewed in terms of mechanistic constraints. A smaller 

whale can turn quicker than a larger whale, and a small fish can turn faster than any whale. 

All strategies of hunting and feeding vary with many factors relating to prey size and 

therefore the prey size and behaviour (for example schooling) will determine foraging 

behaviour 

Relatively little is known about potential age/sex related differences in the feeding 

behaviour of killer whales. In the marine mammal hunts where killer whales partially strand 

themselves, such behaviour is not performed by adult males, probably due to their larger body 

size which gives them a greater risk of getting permanently stranded. However, in New 

Zealand, where killer whales feed on rays in very shallow waters, both sexes participate in 

feeding. Adult females seem to be the ones taking tuna from longlines in the Gibraltar strait, 

while both sexes are engaged in this behaviour in New Zealand. It has been suggested that 

adult males would have an important function in feeding behaviours where deep and/or long 

dives are needed. In Norway killer whales occasionally chase up herring schools from 150- 

300 meters depth. However, the dive data collected in the satellite tracking study does not 

indicate that the adult males would make longer or deeper dives than subadult females. On the 

contrary, the deepest and longest dives have been made by 8-10 year old females. 

In almost all marine mammal kills by transients, food sharing is observed. This is often 

detected by observing gulls following different group members as they tear up prey and leave 

scraps behind. In New Zealand killer whales are observed sharing food (including several 

observations of adult males sharing food with young calves) regardless of the age/sex of the 

animal killing the prey or the type of prey. The killer whales feeding on herring schools in 

Norway stun their prey with tailslaps before feeding; other whales than the ones performing 

the tailslaps also feed on the stunned prey. 

When killer whale prey species are known, research projects studying the foraging 

ecology of killer whales benefit from cooperation with scientists studying the behaviour of the 

prey species. In the Norwegian study, cooperation with herring biologists has been of vital 

importance in understanding the behaviour and habitat use of killer whales. One important 

aspect of the biology of the prey species is their sensory abilities; especially knowledge about 

hearing and vision are important in understanding the techniques killer whales use while 

hunting 



8

The way prey avoids killer whale predation has been documented in several areas. Seals 

are known to move to higher ground, hide in kelp and dive close to seamounts and seafloor 

when killer whales are present and rays hide in shallow waters, between wharf pilings, in rock 

pools or even leave the water.. The preference for feeding on young marine mammals is 

probably related to the fact that naive prey is probably much easier to kill. Older individuals 

can be both more difficult and more risky to catch (pinnipeds, large cetaceans and some 

elasmobranchs are capable of injuring killer whales). 

The importance of habitat in foraging behaviour has received relatively little attention 

and it was suggested that physiographic features of different ocean basins should be 

investigated to understand better the foraging strategies of killer whales. Killer whales feeding 

on fish are known to use underwater seamounts in herding their prey. Marine mammal 

feeding killer whales are known to use passive listening in locating prey and this behaviour 

must be influenced by sea surface state and ambient noise levels. In addition, underwater 

visibility can potentially affect the hunting success of killer whales. In this context it was also 

noted that the presence of a research vessel can affect the observed foraging behaviour. The 

engine noise can alert marine mammal prey to a potential hiding place and hinder foraging 

behaviour of transient killer whales by masking sounds made by prey. In Norway, herring 

schools have been observed reacting to engine noise (especially outboard engines). 

Future research 

To understand the underlying mechanisms shaping specialist/generalist killer whale 

populations, modelling prey abundance and occurrence for areas where specialist and 

generalist populations occur, would be useful. 

The fact that the behaviour of the killer whales feeding on marine mammals and fish in 

the Northeast Pacific is very different, raises some interesting questions regarding the killer 

whales with a mixed diet. Future studies should focus on describing the acoustic behaviour of 

the same killer whale groups while foraging on marine mammals and fish. 

To be able to compare the foraging behaviour of different populations, collaborative 

projects are encouraged. By using at least the same methodology, preferably also same 

observers, it would be much easier to compare the foraging behaviour of different 

populations. 

Research on fatty acid analysis is recommended to determine if it can be used to 

identify the diet of killer whales. Controlled experiments should be carried out on captive 

killer whales where diet can be manipulated to look for differences in fatty acid profiles. 

The way prey size affects hunting behaviour and food sharing should be studied in an 

area where transient killer whales are frequently observed feeding on different sized marine 

mammal prey (for example Monterey Bay area). 

Understanding the foraging behaviour of a killer whale population can benefit from 

cooperation with scientists studying the behaviour of the prey species. 



9

The use of satellite telemetry has shown to be a powerful tool in understanding the 

range, habitat use, movement pattern and diving behaviour of killer whales. However, the use 

of this technique is not recommended unless there is enough baseline information on the 

whales to be studied and there are important question/questions which can not be answered in 

another way. 



10

KILLER WHALE WORKSHOP - CONSERVATION 

27 SEPTEMBER 2002 

ANDREW TRITES, CHAIR 

Participants 

Andrew W Trites University of British Columbia Canada 

Lea David CEBC-CNRS France 

Marthán Bester University of Pretoria South Africa 

Fabierre Delfour University of Grenoble France 

Miguel Iniguez Cethus Foundation Argentina 

Alexandra Mironova Sevostrybvod Russia 

Birgit Kriete Orca Relief USA 

Stefan Jacobs Center for Whale Research USA 

Jodi Smith Orca Conservancy USA 

Nic Dedeluk Vancouver Aquarium Canada 

Marc Pakenham Fisheries and Oceans Canada 

Peter Ross Fisheries and Oceans Canada 

Margie Morrice Deakin University Australia 

WORKSHOP REPORT 

• The workshop participants recognized that we had broad geographic representation, with 

the exception of Norway 

• Conservation was assumed to reflect the maintenance of healthy abundant populations of 

killer whales now and in the future 

• Seven threats to the conservation of killer whales were identified. They included habitat 

loss, reductions in prey abundance, effects of climate change, lack of governance, whale 

watching, pollution and the possible effects of exotic species introduced into the marine 

environment. 

• Workshop participants were asked to rank the importance of these issues at local and 

global scales (Appendix 1). Participants recognized that the 7 potential risks were not 

necessarily mutually exclusive. 

• Weighting the collective responses of the participants (Appendix 1) indicated the highest 

local conservation concerns were: 

o Changes in prey, 

o Pollution, 

o Whale watching, and 

o Habitat loss. 

• Globally, the participants felt the highest concerns stemmed from: 

o Pollution, 

o Changes in prey, 



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o Lack of governance, and 

o Climate change. 

• It was recognized that there are major overlaps and connections between these threats. 

• Given that killer whales are fairly adaptable, one means of identifying key threats is to 

consider what might affect the carrying capacity of killer whales (i.e., what controls their 

birth and death rates). As such, key threats are likely related to factors that affect: 

o Quality and quantity of food, and 

o Direct mortality 

• We proceeded by defining the 7 key conservation concerns for killer whales and identified 

the key issues and information needs for each (i.e., what do we know and what do we not 

know in terms of what is needed for conservation, where are the gaps and what are the 

solutions and priorities). 

7 Threats to the Conservation of Killer 

Whales 

1. Prey Abundance and Fishing 

Killer whales need to be able to access a relative abundant supply of high quality prey 

unfettered by human activities in the ocean. 

Highest research priorities are to determine and monitor: 

• What do they eat? 

• How much? 

• What is the abundance of prey? 

Medium priorities are to determine: 

• Where do they eat? 

• Quality of prey and how does it vary by season? 

• What are the competitive interactions? 

Other Questions: 

• How do they eat/capture prey? 

• How dependant are killer whales on by-catch and fisheries caught prey? 

• What are the implications of killer whales predation on the food web? – develop 

ecosystem models 

• What is the status of killer whales prey? 



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• Are killer whales opportunistic or specialist feeders? 

2. POLLUTION 

Anthropogenic pollution knows no national borders, and many contaminants can affect the 

health and abundance of killer whales and their prey. 

Research priorities: 

• What are the short and long term affect of pollution on killer whale health? 

• Characterize and quantify the pollutant, and determine and predict the direct and 

indirect effects on killer whales. 

o PBTs – old and new (high) 

o CLUPs (high) Coastal Localized Urban Pollutants 

o noise (high) 

o marine debris (high) 

o oil (medium) 

o air (medium) 

o eutrophication (medium) 

3. Whale watching 

Whale watching activities can introduce noise, pollutants and physical intrusions that impede 

the natural life processes of killer whales (feeding, resting, socializing, breeding and thriving). 


• Quantify and qualify the extent of commercial and recreational whale watching (numbers, 

time, distance and area). 

• Determine what qualifies as whale watching. 

• What is the economic, social and intrinsic value, and hence the conservation value of 

killer whales? 

• What effects does whale watching have on killer whales (at the individual, matrilineal 

line, clan level) in the short term and the long term? How do the following factors affect 

killer whales: 

o noise (high research priority) 

o pollution (high) 

o behaviour changes (high) 

o prey distribution (medium) 

o collision (medium) 

o physiological changes (medium) 



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4. Habitat loss 

Habitat encompasses inshore and offshore waters, including terrestrial watersheds needed 

by killer whales and their prey for normal life processes and can be reduced by human activities 

such as urbanization, fishing, pollution, climate change, etc. 

High Research Priorities: 

• Identify killer whales habitat and how it changes seasonally. 

• Understand how human activity affects this killer whales habitat through: 

o Noise (high research priority) 

o prey reduction (eg. fishing, deforestation) (high) 

o pollution (toxics, turbidity, debris) (medium) 

o presence (medium) 

Medium Priorities: 

• Typify killer whales habitat according to use (eg. feeding, resting, socializing, 

traveling, breeding etc.). 

5. Introduction of Exotic Species 

Global transport of humans, their goods and animals leads to the introduction of exotic marine 

plants, organisms and pathogens into killer whale habitat, that might affect the health of killer whale 

populations and their prey. 


• What affects might exotic species have on killer whales? 

o disease (high research priority) 

o Competition (medium) 

o Prey (medium) 

o Aquaculture/hatcheries (medium) 

• What exotic species have been introduced? (medium) 



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6. Lack of Governance 

The wise application of knowledge at the individual, local, national and international levels to 

minimize human impacts on killer whales and their habitat. 

High research priorities: 

• Compile population specific Tables outlining what is known and not known about 

killer whale populations throughout the world. 

• Assess the status of killer whale populations throughout the world using 

internationally accepted standards, and identify information required for populations 

that are deemed data deficient. 

• Review and implement adequate planning and management mechanisms that are in 

keeping with the precautionary principle to manage human activities that affect killer 

whales. 

Medium priorities: 

• Develop an international set of stewardship protocols and ethics for the treatment of 

killer whales (i.e., concerning issues related to entrapment, emergency responses, 

research, captures and aquarium displays). 

• Develop and implement a means for the rapid exchange of information/knowledge 

between authorities/community that will lead to greater cooperation and coordination 

at all levels (e,g., researchers, public, governments, managers, fishers, commercial 

operators). 

7. Climate Change 

Climate change resulting from greenhouse gases will alter ocean productivity and may lead to 

potentially catastrophic changes in the abundance of preferred killer whale prey species. 


• Link climate change research to killer whales. 

• Develop ecosystem models to evaluate the effect of changes in prey numbers to killer 

whales. 

GENERAL COMMENTS 

• It is important to recognize that there are linkages between the 7 concerns outlined above, 

and that they are not mutually exclusive (e.g., whale watching occurs in urban areas where 

there are stresses from pollution, etc.). 

• Discussion ensued over how to better engage the public in the conservation needs of killer 

whales. From this stemmed the idea that we should establish and promote a Charter of 

Rights for Killer Whales. 

• Each workshop participant was asked to consider what should such a Charter of Rights 

include. Participants felt that killer whales should be able to: 



15

o live in a clean, quiet and healthy environment 

o use their habitat freely and unharmed 

o have the freedom to travel and feed where they choose 

o consume prey that are abundant and free of toxins 

o rest without harassment 

o socialize and communicate freely 

o be free and protected by local, national and international laws 

o not be captured for human entertainment and unwillingly separated from family 

members 

• No consensus was sought on a final text for the Charter of Rights. Instead the 

Conservation Workshop participants decided to present the concept to the other workshop 

groups with the recommendation that it be further developed in time for the next Killer 

Whale Symposium for possible signing by researchers or governments. 



16

Appendix 1 

Top 3 threats to killer whales identified by workshop participants at local and global 

levels. 

Russia: 

Local Global 

1. Pollution, habitat loss, 

2. fisheries interactions (prey), 

3. captures (direct impact on killer whale 

population) 

British Columbia/Washington State: 

1. Whale watching, 

2. over fishing, 

3. pollution 

1. Habitat loss, 

2. whale watching, 

3. pollution. 

1. Pollution, 

2. habitat loss, 

3. whale watching 

1. Disturbance/harassment, 

2. prey (habitat loss/fisheries), 

3. pollution. 

1. Climate change (prey) 

2. PBT (prey), 

3. fishery interactions (over fishing). 

1. Fishing (prey availability), 

2. pollution, 

3. whale watching. 

1. Prey (natural and fishery), 


3. toxics. 

Australia: 

1. Governance, 

2. habitat loss (prey), 

3. fishery interactions (shooting and 

1. Climate change (prey and environment), 

2. pollution, 

3. governance. 

1. Pollution, 

2. fisheries (over fishing), 

3. whale watching. 

1. Pollution, 

2. climate change, 

3. habitat loss. 

1. Fishery interactions (prey), 

2. habitat loss ( urbanization), 

3. governance (lack of knowledge) 

1. Prey, 

2. pollution, 


1. Fishing, 

2. pollution, 


1. Prey, 

2. toxics, 




3. habitat loss and pollution. 



17

ehavior change and prey). 

Mediterranean Sea: 

1. Pollution, 

2. fishery interactions, 

3. whale watching/ boat traffic 

1. Pollution (debris), 

2. disturbance/ harassment (boats), 

3. fishery interactions (prey and shooting). 

Prince Edward Islands: 

1. Fishery interaction (operational, 

shooting, entanglement), 

2. biological interactions (removal of prey), 

3. pollution. 

South Western Atlantic: 


2. fishery interactions (Antarctic cod, 

swordfish), 

3. habitat loss (cultural-core use areas) 

Alaska Prince William Sound: 

1. Prey, 


3. toxics 

1. Pollution, 

2. fishery interactions, 

3. whale watching/ boat traffic 


2. prey, 

3. pollution 

1. Fisheries, 

2. pollution, 


1. Habitat loss, 



1. Prey, 


3. toxics 



18

KILLER WHALE WORKSHOP - ACOUSTIC 

Participants: 

John Ford fordjo@pac.dfo-mpo.gc.ca (Facilitator and Rapporteur) 

Harald Yurk yurk@zoology.ubc.ca (Assistant Rapporteur) 

Ari Shapiro smiling_whale@earthlink.net (Assistant Rapporteur) 

Volker Deecke deecke@zoology.ubc.ca 

Renaud de Stephanis renaud@teleline.es 

Olga Filatova alazor@rambler.ru 

Andrew Foote andrew.foote@hotmail.com 

Antoine Godefroid spiroutonio@hotmail.com 

Sarah Graham mickeylegs@yahoo.com 

Teo Leyssen teoleyssen@belgacom.net 

Nicola Rehn nicola.rehn@arcor.de 

Eva Saulitis saulitis@pobox.xyz.net 

Silvia Scali silvia_scali@yahoo.it 

Malene Juul Simon mjsimon@zi.ku.dk 

Frank Thomsen thomsen@zoologie.uni-hamburg.de 

Brigitte Weiss a9400355@unet.univie.ac.at 

_____________________________________________________________________ 

The objective of the Acoustic Workshop was to focus discussion on a number of topics 

related to the recording, analysis, and interpretation of underwater acoustic signals of killer 

whales. These included discussion of recent advances in the technologies involved in field 

recording and laboratory analysis of killer whale sounds, the use of acoustics as a tool in field 

studies, the description and definition of acoustic signals, and the state of knowledge 

regarding the function of these signals. Discussions also focused on important gaps in our 

knowledge of killer whale acoustic behaviour, and how these might be filled. The following 

represents a synopsis of these discussions. 

Recording and Analysis: 

Advancing technology has provided many exciting new opportunities for the recording 

and analysis of killer whale acoustic signals. A number of hardware and software options are 

now available for all stages of acoustic data acquisition and analysis. 

Most field studies of killer whale acoustics involve recording signals from a small boat 

using a portable hydrophone and recorder system. To record social communication signals, a 

single omni-directional hydrophone with built-in preamplifier having a receiving sensitivity 

of at least -150 to -170 dB re 1 µPa over a frequency band of 100 Hz to 20 kHz is quite 

adequate. Recordings where bearing and distance to sound sources require more complex, 

multi-element hydrophone arrays. Recordings of killer whales suitable for description of the 

basic structure of call types up to 15 kHz can be recorded using a professional-calibre audio 

cassette recorder. Few manufacturers currently make these types of recorders, although 

Marantz produces several good models in both mono and stereo formats. Reel-to-reel 

recorders are becoming scarce, but have the capability of making excellent recordings with 



19

wide frequency response (up to 40 kHz or so) and good dynamic range. The Nagra IV is an 

example of a quality, field-capable reel-to-reel recorder. 

Most field researchers recording sounds of killer whales use Digital Audio Tape (DAT) 

recorders, which provide sampling rates up to 48 kHz, or an audio bandwidth to 24 kHz. The 

group recommended Sony models (e.g. D7, D8, D10 or D100) of DAT recorders. Tascam 

also produces good DAT recorders, although they have no time/date indexing, which could be 

a disadvantage in behavioural acoustic studies. Digital video recorders can record highquality 

16-bit audio tracks comparable to DAT recordings, and have the advantage of 

documenting concurrent surface behaviour of animals. However, most have Automatic Gain 

Controls (AGCs) rather than manual record level controls, which are not well suited to the 

loud, punctuated nature of killer whale clicks and calls. Mini-disc recorders are not 

recommended for scientific recordings, since they involve a lossy compression algorithm, 

which affects the accuracy of spectral analyses. Recording directly to hard disks on portable 

computers can yield high quality data, though many laptops are not robust enough for use in 

small boats in the marine environment. Larger ‘lunch-box’ style portable computers allow for 

the use of high-speed signal processing cards, which can yield extremely wideband recordings 

of echolocation clicks when used with appropriate broadband hydrophones. 

For data archiving, it should be noted that analogue tape media (reel-to-reel and audio 

cassette) are unlikely to survive more than 20-30 years. Many reel-to-reel tapes from the 

1980s and earlier cannot be read today due to sloughing of the magnetic coating on the tapes. 

Recordable CD and DVDs (CD-R and DVD-R) are expected to have a longevity of 50-75 

years, so digital transfer to this medium may be useful for archiving data. Other options for 

data archiving include contributing to institution-based acoustic archiving programs, 

including those at the British Museum of Natural History and Cornell University. 

In recent years, a variety of acoustic analysis software packages have become available 

that are very useful for killer whale studies. CoolEdit 2000 is a popular and inexpensive 

program that offers both spectrographic or waveform displays in real-time and a variety of 

other functions. One limitation is its inability to print spectrograms. Another popular tool, 

though far more expensive, is Avisoft-SASLab Pro, a program that is designed for 

bioacoustical analysis. It produces excellent spectrogram hardcopies. Canary, a bioacoustical 

software package from the Bioacoustical Research Program at Cornell University, is also 

widely used. It lacks real-time browsing capability and runs only on Macintosh computers. 

Other programs used in killer whale acoustic studies are Signal RTS, Spectralab, SeaWave 

(University of Pavia, Italy), and various custom programs that run with Matlab (Mathworks 

Inc.). 

Describing and defining signal structure 

Killer whales produce a wide variety of complex acoustic signals which can be difficult 

to describe and define in terms of physical structure and potential function. Clicks are 

thought to be emitted primarily for echolocation purposes, though their potential role in social 

communication requires further study. Pulses – similar in structure to echolocation clicks – 

are often produced at high repetition rates (typically 500 Hz to ≥ 2500 Hz) which give the 

aural impression of a continuous tone. Spectrographically, these signals are resolved as a 

series of sidebands at intervals equivalent to the pulse repetition frequency. Most killer whale 

calls are composed of such rapidly produced pulses. Energy is not necessarily greatest in the 



20

lowest band, and burst-pulsing can result in complex sideband patterns. Some killer whale call 

types show two concurrent but different pulsing frequencies. Whistles are continuous 

waveforms that are heard mostly in socializing contexts. Pure-tone whistles are represented 

spectrographically as a single band, often with significant frequency modulation. Many 

whistles have one or two well defined harmonics at multiples of the fundamental tone 

frequency. 

Pulsed calls that are heard repetitively with various degrees of stereotypy are referred to 

as discrete call types. Discrete calls seem to be characteristic of killer whales in all global 

regions where they have been recorded. Often different discrete call types are easily 

distinguished by ear because of distinctive physical features (rapid modulations or abrupt 

shifts in pulse rates, overlapping pulse rates, etc.) and high stereotypy. In many cases, 

however, there are considerable variations in call structure, and clear definitions of call types 

are confounded by gradations between otherwise distinctive forms. There are several 

approaches to objectively and consistently defining call types. Repeated aural examination 

(listening carefully and often) combined with visual inspection of spectrograms can reliably 

identify most call types. Call types should also be defined quantitatively using measurements 

of duration and sideband interval for each distinctive element (= components, segments or 

parts of calls defined by abrupt shifts in pulse rate). These measurements can be used in 

univariate or multivariate statistical analyses to distinguish similar call types. Other 

approaches to defining call types include the use of neural networks and other automated 

pattern recognition techniques. These are especially useful to distinguish fine-scale 

differences in shared calls, or in objectively defining categories within highly variable 

repertoires. It should be recognized that human-based call type classifications, regardless of 

how quantitatively valid they may be, are not necessarily the same as those perceived by the 

killer whales themselves. 

Function of killer whale social signals 

Field studies in British Columbia and Alaska have shown that pods (groups of closely 

related matrilines) of resident-type (fish feeding) killer whales have stable repertoires of 7-17 

discrete call types. These repertoires appear to be shared by all pods members, and are likely 

learned by individuals through mimicking older kin within the group, especially their 

mothers. Repertoires are thus perpetuated in maternal lineages by a process of cultural 

transmission across generations. Consistent differences, often referred to as dialects, exist in 

the call repertoires of pods within an area. Pods that share calls (i.e., have related dialects) 

belong to the same acoustic clan. Different clans appear to represent distinct, independent 

maternal lineages that have persisted for many generations, and have independent call 

traditions. 

Call repertoires, and the group-specific dialectal variations that exist within them, likely 

serve as a means of maintaining kin-group identity and cohesion, and coordinating group 

behaviours and activities. Recent genetic evidence indicates that dialects also influence 

selection of mating partners, thus serving as an outbreeding mechanism within killer whale 

communities. Although the frequency of use of call types varies with activity context in 

killer whale pods, no call has been shown to be tied exclusively to any particular behavioural 

context or circumstance. 

Dialects within clans appear to develop over time through the accumulation of 

consistent group-specific variations in call structure coincidental with a process of fission 



21

within the lineage. The actual process of dialect change is poorly known. Recent studies 

have described fine changes in the structure of call types shared by two matrilines of northern 

residents in British Columbia. Each matriline had parallel changes, as if one matriline had 

copied changes from the other. This apparent synchrony of calling behaviour over time has 

implications of defining a “cultural clock”, or the rate of dialect change within clans. Dialect 

change may also occur in a punctuated manner, corresponding to sudden social or 

demographic changes within a lineage. 

Whistles in resident killer whales are strongly associated with socializing contexts, as 

are variable pulsed calls. These sounds appear to be used as close-range communication 

signals, often occurring together with physical interactions and visual displays. Whistles may 

also occur repetitively with levels of stereotypy approaching those of discrete calls. 

Mammal-hunting transient killer whales from Southeastern Alaska, British Columbia 

and California share a related call repertoire. The lack of kin-group-specific dialects in 

transients is no doubt related to their social system, which is more fluid and dynamic than that 

of resident killer whales. Nonetheless, there appear to be some regional variations in call 

repertoires within the west coast transient community. 

Studies of killer whales in regions other than the Northeastern Pacific have revealed 

similar patterns of acoustic behaviour, with signals being dominated by repetitive, stereotyped 

pulsed calls. Regions where discrete call types have been identified include Norway, Iceland, 

the Kamchatkan area of eastern Russia, Argentina, and Antarctica. 

Structure and Function of Echolocation Signals 

Echolocation has been relatively little studied in killer whales compared to the social 

signals of the species. Early captive studies demonstrated that, as with most odontocetes, 

killer whales are able to orient in their environment and detect objects through the use of 

series (or ‘trains’) of echolocation clicks. Field studies in British Columbia and Alaska have 

described major differences in the echolocation behaviour of resident and transient killer 

whales, apparently associated with the different hunting specializations of theses two 

ecotypes. Fish-feeding residents frequently emit echolocation click trains while foraging, but 

transients do not. Instead, transients forage either in silence, or sporadically produce isolated 

clicks. Suppressed echolocation activity in transients appears to be a tactic for hunting 

mammalian prey, which have excellent hearing abilities and would be alerted to the predators’ 

approach if they detected echolocations signals. 

Recent field studies have focused on describing echolocation signal structure in killer 

whales through the use of wide-band recording systems and arrays of hydrophones. Such 

studies in Norway and British Columbia have found that killer whale clicks are similar to 

those of other delphinids, though they tend to have lower frequency emphases than do the 

clicks of smaller dolphins. Further research is needed to describe the function of killer whale 

echolocation in better detail. 

Acoustics as a Tool 

Underwater acoustics not only provides a means of interpreting killer whale behaviour 

and social structure, it can also be used as a tool for other purposes. Fixed shore-based 

hydrophone installations at strategic coastal sites can provide a means of remotely monitoring 



22

the presence of killer whales throughout the year, day and night in all weather conditions. 

Discrete or stereotyped calls can provide information on the identity of vocalizing killer 

whales groups. In British Columbia, remote monitoring installations at lighthouses have been 

used successfully for many years. These systems are monitored by lightkeepers, who make 

recordings when whales are heard. More recently, automated recording systems have been 

developed, which utilize call-recognition circuitry to trigger digitization and recording of 

acoustic signals when whale vocalizations are received. 

Underwater acoustic monitoring from boats can be used as an aid to locating groups of 

killer whales during field studies. Whale calls can be detected at ranges up to 20 kilometres 

in quiet conditions, well beyond the range of visual detection. To help locate vocalizing 

animals, an omni-directional hydrophone can be fixed in the mouth of a neoprene-lined bowl, 

which provides directionality when suspended over the boat’s side and scanned laterally (gas 

bubbles in the neoprene provide acoustic reflectivity underwater). Towed hydrophone arrays 

deployed from ships undertaking visual surveys may also detect distant killer whales, and can 

provide a bearing to their location. 

Playback of killer whale calls has been employed in field studies of the species and its 

prey. While potentially yielding insight into killer whale behaviour and ecology, playbacks 

have the potential to be very disruptive to the animals and may elicit violent responses. 

Experimental design of playback studies need to be well developed, and research questions 

must be clearly defined, in order for the study to have interpretable results. Close attention 

must be paid to the acoustic fidelity of the recordings being used and the playback apparatus. 

Playbacks could potentially be used to attract animals from a distance, particularly transient 

killer whales, which could aid in locating groups for study. They also have potential value as 

a management tool, to attract or repel whales from dangerous locations, such as during an oil 

spill. 

The Impacts of Noise on Acoustic Behaviour 

Increasing levels of anthropogenic noise, such as that associated with vessel traffic, 

seismic exploration, and military operations, are of growing concern. In some regions, killer 

whales frequent waters with intense levels of marine traffic, including fish boats, whale-watch 

vessels, and commercial shipping. Recent studies have suggested that typical levels of 

ambient noise in waters off southern Vancouver Island, British Columbia, are sufficient to 

cause temporary reduction in hearing acuity in resident killer whales, and permanent 

sensitivity shifts in extreme cases. Reduced hearing sensitivity could have major impacts on 

the ability of killer whales to function acoustically. Noise also has the potential to mask the 

calls of distant conspecifics, or the faint echoes from objects being investigated acoustically. 

Further research is needed to better understand the hearing abilities of killer whales, 

particularly with respect to critical bands and critical ratios. The effect of noise on the 

echolocation or social signal production also requires study, to determine if the animals 

compensate for ambient noise levels by changing vocal activity or source levels of sound 

production. 

Research Questions for Future Consideration 



23

The following summarizes a variety of research questions and knowledge gaps that 

were identified and discussed by the Acoustics Workshop participants. Many of these relate 

to the general topics described above, while others do not. 

o How important is passive listening in killer whales for acoustic orientation and 

discrimination? 

o What are the social functions of echolocation click production? Are clicks used to 

determine location of other matriline or pod members? 

o Do killer whales alter the frequency structure of echolocation clicks according to the 

nature of the target being searched for or examined acoustically? Does echolocation click rate 

vary with target range? 

o What is the origin of acoustic clans? Do the major acoustical differences seen among 

clans represent founder effects? Are clans typical of killer whale populations in regions other 

than the Northeast Pacific residents? 

o To what extent is the identity of vocalizing individuals encoded in discrete call types 

shared by kin members? 

o Are dialectal differences within clans the result of random drift, or are vocal changes 

directed? 

o Are call type classifications described in acoustic studies perceived in the same way 

by killer whales? Could the ability of killer whales to discriminate call types and variations 

be tested in a captive setting? 

o Are there anatomical or physiological influences or constraints on sound production in 

killer whales? Could structural features in signal structure encode sex, age, or populationspecific 

information? 

o Why are their such great differences in the sizes of call repertoires among resident 

killer whales? 



24

KILLER WHALE WORKSHOP - POPULATION DYNAMICS, POPULATION 

STRUCTURE, AND LIFE-HISTORY 

Participants: 

Lance Barrett-Lennard and Rob Williams 

L. Barrett-Lennard, M. Chambellant, R. DeLeuwl, K. Delord, C. Gasparrou, A. van Ginneken, K. Heise, 

K. Irish, P. Mäkeläinen, C. Matkin, P. Olesiuk, E. Poncelet, A. Schaffar, M. Ugarte, R. Williams 

Introduction 

Systematic study of killer whales began in the early 1970’s, when Michael Bigg and 

colleagues investigated the distribution and abundance of the species in southern British 

Columbia and Washington State (Bigg & Wolman 1975; Bigg 1982). Their research 

provided the impetus and foundation for a series of killer whale studies in the northeast 

Pacific that carry on to the present day (eg Bigg et. al. 1990, Olesiuk et al. 1990, Ford et al. 

1998, Matkin et al. 1999). Reliable photo-identification of individuals was and is at the core 

of these studies. However, additional methods relying on the analysis of behaviour, acoustic 

signals, movement patterns, and/or DNA are now routinely employed. The long-term studies 

in the northeastern Pacific have generated a wealth of information on killer whale population 

dynamics, population structure, and life history. Studies of killer whales in other areas are at 

an earlier stage, but are nonetheless producing many valuable insights as well (eg Guinet 

1992, Similä et al. 1996, Visser & Mäkeläinen 2000). 

At the beginning of this workshop, the participants agreed to focus on methods of killer 

whale field research and data analysis rather than on research results, since recent findings 

were covered thoroughly during the symposium that preceded this workshop. It was 

recognized that the research of Bigg and his British Columbian colleagues is being used as a 

general model for most other killer whale field studies. Therefore, much of the discussion 

revolved around the specifics of the British Columbian methods, their advantages and 

disadvantages, contexts under which they do and do not work well, and how they can and 

should be improved on in new studies. Also discussed were methods such as formal markrecapture 

analysis that are commonly used in other wildlife studies but that have not been 

widely used in killer whale studies. Finally, the participants had a brief discussion about the 

utility and validity of comparing population and life history parameter estimates between 

populations of killer whales. 

Methods of Field Research on Killer Whale Populations 

Photo-identification 

Killer whales are large animals in small populations, and as such do not lend themselves 

to many of the classical methods of population analysis used for other species. Fortunately, 

tracking the histories and fates of individuals directly using the technique of photoidentification 

is well-established and practical. Participants familiar with killer whale photoidentification 

offered the following recommendations: 

− good quality photographs are essential (see Bigg et al. 1986) 



25

− film produces the highest-resolution images and is recommended over digital 

photography (although with technical improvements digital will likely take over as the 

medium of choice in the future) 

− images from video stills are almost worthless for killer whale photo-identification 

− when the film is analysed, it is recommended that every identifiable individual in 

every image be entered in a long-term database 

In British Columbia, identification photographs have been extremely useful for analyses 

of association patterns. In these analyses the frequency with which any two individuals are 

either identified together in the same image or appear in consecutive images is used to 

calculate an objective index of the strength of their social affiliation. A general discussion of 

the application of photo-identification to association analysis ensued. van Ginneken 

questioned the utility of association indices based on the number of photographic events, 

rather than the total time spent together. Olesiuk agreed, and noted that if the study were 

starting again, he would want to see proximity and time spent together measured, rather than 

simple presence in the same encounter/ consecutive image. He said that the method worked 

well in the BC study largely because of the enormous database: more than 50,000 frames—it 

would not work as well in smaller studies. Barrett-Lennard pointed out that in the first 15 

years of research in BC, researchers attempted to photograph groups of killer whales in single 

images, but in recent years there has been more emphasis on full-frame photographs as 

individuals--making association analysis by this method more difficult. According to the 

methods used to date, this will indicate a weakening of the strength of association for many 

pairs. Olesiuk agreed and noted that field researchers would do well to identify photographic 

sampling criteria and stick to them. Several researchers noted that 1) regardless of the criteria 

used regarding the number of whales per image, it is best to work systematically through 

each group of killer whales in every encounter and 2) although the models established in the 

early British Columbia studies are general helpful, researchers should establish photographic 

sampling protocols based on the objectives of their own studies. 

In addition to association analysis, identification photographs are used to estimate 

abundance. A discovery curve is a useful way of generating a rough abundance estimate. In 

this approach, one simply plots the total number of identified whales that have been 

catalogued in each year of an study. When the total number of identified whales levels off 

despite ongoing photo-identification work, it is assumed that most of the individuals in the 

population have been identified. A second approach is sight / re-sight analysis. Here, a 

researcher photographs as many whales as possible in the study area over a defined sighting 

period. At a later point, he or she repeats the exercise, and then analyses the photographs to 

determine how many of the individuals were sighted twice. In the method’s simplest form, 

the ratio of the number sighted twice to the total number sighted is assumed to be equal to the 

ratio of the total number sighted to the total population. Many sophisticated variants of this 

basic relationship are described in the literature. Care must be taken when using photoidentification 

data in sight / re-sight analysis because abundance estimates are strongly 

influenced by photo-quality and animal distinctiveness. A powerful way of eliminating the 

bias is to split the process into three stages: one observer or group of observers scores photoquality, 

another scores animal distinctiveness, and the most experienced observer scores 

matches between samples. 

Acoustic Analysis 

John Ford’s study of killer whale calls in late 1980’s and early 1990’s showed that 

British Columbian killer whales use group-specific call repertoires. Furthermore, he showed 



26

that resident killer whales have both pod-specific and clan-specific dialects (Ford 1991). 

Transient killer whales have smaller repertoires than residents, but at least three populations 

of transients in the northeast Pacific can be distinguished acoustically. Although they are 

usually vocally active, resident killer whales occasionally travel silently. In contrast, 

transients are usually silent, vocalising most frequently after they make a kill. Little is known 

about the call repertoires of the offshore population of killer whale, but members of this group 

are usually vocal during their rare visits to the coast. Inter-population differences in call 

repertoires have proven to be so stable in British Columbia that they are now used to assign 

“new” groups of killer whale to existing populations. 

Hydrophones stationed in remote areas of British Columbia and Alaska have been used 

to monitor killer whale movements year-round for many years. While silence on the 

hydrophone does not necessarily indicate that killer whales are absent, calls provide proof that 

they are present. Indeed, calls not only indicate the presence of killer whales, but also reliably 

discriminate populations and, in some cases, specific groups of individuals. At the present 

time, the most reliable remote hydrophones are ones that broadcast their sounds continuously 

on a radio or microwave frequency so that they can be monitored by local residents. 

However, promising developments have been made with hydrophone systems that monitor 

continuously but broadcast and/or record only when killer whale called are detected. The 

workshop participants agreed that these methods could be very useful. A project is currently 

underway to investigate the practicality of using acoustic monitoring to assess transient killer whale 

predation on Steller sea lions in western Alaska. 

In general, the workshop participants agreed that acoustic analysis is a useful way to 

identify population structure, and recommended that it be incorporated into killer whale field 

studies wherever possible. 

Genetic Analysis 

Genetic analysis can shed light on both social organisation and population structure in 

killer whales and other species. For example, Stevens (1989) and Hoelzel & Dover (1991) 

showed fixed differences in mitochondrial DNA between sympatric and parapatric 

assemblages of killer whales in British Columbia, providing the first convincing evidence that 

they are, in fact, closed populations. Later, mating systems of resident killer whales in British 

Columbia and Alaska were elucidated using two genetic techniques, one based on paternity 

screening and another on allele frequency analysis (Barrett-Lennard 2000). The latter study 

provided evidence of effective inbreeding avoidance despite the lack of permanent dispersal 

of members of either sex from their natal pods. Both Hoelzel et al. (1998) and Barrett- 

Lennard (2000) documented low levels of genetic diversity in killer whales in the northeast 

Pacific. 

Genetic analyses can be performed using small samples of skin procured with biopsy 

darts (Barrett-Lennard et al. 1996). While this procedure does not appear to have negative 

long-term consequences for killer whales, two factors need to be considered in deciding 

whether to incorporate biopsy sampling into a field study. First, acquiring samples involves 

repeated close approaches to whales, constituting a form of harassment. Permits may be 

difficult to procure in some jurisdictions. Second, biopsy sampling take considerable time, 

and has the potential to interfere with other field research methods such as photoidentification 

and acoustic recording. If biopsy sampling is incorporated into a study, plans 



27

should be made to archive samples for posterity and great care should be taken to photoidentify 

each individual sampled. 

The following points were raised in a general discussion. Olesiuk pointed out that the 

genetic contribution of males is not reflected in current population models. Since paternal 

genetic contribution is likely to influence maternal reproductive success, he suggested that 

genetic techniques could reduce the noise in existing models. The question of using genetic 

techniques to estimate effective (breeding) population size was raised by Ugarte. Barrett- 

Lennard pointed out that conventional methods to directly extrapolate effective population 

size from allele frequencies are extremely sensitive to violations of a very restrictive set of 

assumptions (such as random breeding, which is known not to prevail in resident killer 

whales). Newer methods may improve the precision somewhat, but it is unlikely that 

genetics alone will provide a magic bullet for estimating population size. A question was 

raised about the conservation implications of mating system analysis. Barrett-Lennard 

provided an example. The southern resident killer whale population of British Columbia 

contains only three pods. Genetic analysis indicates that mating occurs between, not within 

pods (Barrett-Lennard 2000). This means that the females of the largest pods have very few 

potential mates---a situation that may be exacerbated by the general failure of young adult 

males to father calves. The results suggest that many calves in the next generation may be 

sibs and half-sibs, resulting in a rapid loss of genetic diversity. 

The possibility of doing a sight – resight population estimates of killer whales using 

genotypes instead of photographs was raised. There was general consensus that given the 

difficulty, expense, and invasiveness of biopsy sampling, and the expense of analzying DNA, 

photographic methods are much preferred for the species. However, it was conceded that in 

certain instances with relatively rarely-seen populations it could possibly be used along with 

photographic methods. 

Naming and Grouping Killer Whales in Field Studies 

One of the first problems faced in a new killer whale field study is how to name and 

group identified individuals. The workshop participants felt that establishing an efficient, 

useful, flexible system early in a project was extremely helpful. Since most studies use the 

basic system developed by Bigg and colleagues for resident killer whales, the system is 

described below. A second system developed by the same researchers is also described, and 

is followed by a general discussion. 

Bigg et al. (1990) established a system whereby a unique alpha-numeric code was used 

to designate each individual. A single letter designated the whale’s pod (defined as the largest 

group in a community that travelled together at least 50% of the time). The letter was 

followed by a two-digit number designating the order in which individuals in the pod were 

first identified. Thus, A25 was the twenty-fifth individual identified in A pod. Several years 

after this naming system was established, some of Bigg’s initial pod designations were shown 

to be incorrect. For example A pod in fact comprised three pods. Each of the “revised” pods 

kept the A-designator, but was given a name based on the most distinguishable individual in 

the group. Thus, A25 was reassigned to A5 pod. Recently Ford & Ellis (these proceedings) 

showed that pods are less permanent than originally thought and proposed that matrilines, not 

pods, be considered the fundamental units of social organisation in resident killer whales. In 

sum, although the resident naming system has worked for book-keeping, it does not serve as a 

reliable template of resident killer whale social organisation. 



28

Bigg also used the alphanumeric system described above to identify transient killer 

whales. However in the early 1990s, it became clear that some transient killer whales 

disperse between groups, and the naming system once again failed to serve as a template for 

social structure. A revised naming system was devised that gave every transient animal with 

an unknown mother a name beginning with T (for transient) followed by an arbitrary number. 

When calves are born to these animals they receive their mother’s name followed by a letter 

indicating their birth order. Thus, T106B is the second calf of T106. These names work well 

at present but will become unwieldy when strings of several letters are added to a name. In 

addition, if a calf is born and dies before being named, the birth order implied by the 

alphanumeric code may be misleading. 

Under both the resident and transient systems, killer whales are assigned names based 

on their relationships. When new killer whales are first seen, they are not named until these 

relationships are understood. This is not a problem in British Columbia, where it is rare to 

encounter new killer whales. It is a problem in a new study in western Alaska led by Matkin 

and Barrett-Lennard where the rate of discovery is high and where very little is known about 

relationships. In that study, abitrary numeric names are now being assigned as whales are 

identified. These may be replaced with relationship-based names as the study proceeds, or 

they may be used to track individuals indefinitely. A similar system is being used for the 

offshore population of killer whales, where individuals are named “Off” followed by an 

abitrary number. 

In the discussion, Mäkeläinen pointed out that studies are becoming international, and 

she advocated the use of an alphanumeric code that tells researchers which population is 

implied, with an F or M to designate fish-eating or mammal-eating. However, several 

participants argued that our understanding of killer whale ecology may change, and it would 

be problematic to create a global system where names must be changed as new information is 

acquired. Olesiuk argued that a name should contain a fact, such as This is animal X, but not 

contain interpretations of data, such as This is the calf of animal X, and s/he eats only fish. 

These latter methods do not allow for mistakes. van Ginneken stated that females that adopt 

orphans, and naming systems that interpret association with relatedness may mislead future 

researchers. After further discussion the group reached consensus that the naming structure 

used in British Columbia is not necessarily the best way to name whales in new studies. The 

group agreed that whales in new areas should be given a unique identifier that contains no 

interpretation of relatedness or site-fidelity. The consensus is that there should be a central 

database, with an annual meeting to share photographs, and a common naming system. 

Comparisons between populations and studies 

The final part of the workshop asked when it is useful to extrapolate demographic and 

life history parameters obtained from well-studied to less-well studied populations of killer 

whales. Olesiuk pointed out, in the way of an example, that there are very clear links between 

age- and sex-structure of residents under periods of increase and that we can now calculate 

similar values for declining populations. Olesiuk suggested that these values could be used to 

examine the status of transient killer whales, which are inherently harder to study than 

residents. At the very least, the comparisons would suggest areas for future research. 

Barrett-Lennard discussed the fact that in British Columbia no dispersal from resident 

matrilines had been described, while dispersal among transient matrilines definitely occurs. 

He asked whether there was any evidence of either of these systems from other areas. 



29

Poncelet noted that dispersal occurs among pods of elephant seal-eating killer whales at the 

Crozet Islands. Barrett-Lennard noted that transient dispersal is female-biased, and tends to 

occur after female offspring have their first calf. This is similar to the Crozet Islands, and 

suggests that the primary function of dispersal in mammal-eating killer whales is to reduce 

food competition. It was agreed that, with the exception of resident killer whales in the 

northeast Pacific, social structure in killer whales is still poorly understood and should be a 

research priority in future studies. 

Bibliography 

Barrett-Lennard, L.G. (2000). Population structure and mating patterns of killer whales (Orcinus orca) as 

revealed by DNA analysis. Zoology. Vancouver, British Columbia, University of British 

Columbia: 97. 

Barrett-Lennard, L.G., T.G. Smith, G.M. Ellis (1996). "A cetacean biopsy system using lightweight 

pneumatic darts, and its effect on the behaviour of killer whales." Marine Mammal Science 12: 14- 

27. 

Bigg, M.A., A.A. Wolman (1975). "Live-capture killer whale (Orcinus orca) fishery, British Columbia and 

Washington, 1962-73." Journal of the Fisheries Research Board of Canada 32: 1213-1221. 

Bigg, M.A. (1982). "An assessment of killer whale (Orcinus orca) stocks off Vancouver Island, British 

Columbia." Report of the International Whaling Commission 32: 625-666. 

Bigg, M.A., G.M. Ellis, K.C. Balcomb (1986). "The photographic identification of individual cetaceans." 

Whalewatcher 20: 10-12. 

Bigg, M.A., P.F. Olesiuk, G. M. Ellis (1990). "Social organization and genealogy of resident killer whales 

(Orcinus orca) in the coastal waters of British Columbia and Washington State." Report of the 

International Whaling Commission: 383-405. 

Ford, J.K. . (1991). "Vocal traditions among resident killer whales (Orcinus orca) in coastal waters of 

British Columbia." Canadian Journal of Zoology 69: 1454-1483. 

Ford, J.K.B., G.M. Ellis, L.G. Barrett-Lennard, A. B. Morton, K. C. Balcomb (1998). "Dietary 

specialization in two sympatric populations of killer whales (Orcinus orca) in coastal British 

Columbia and adjacent waters." Canadian Journal of Zoology 76: 1456-1471. 

Guinet, C. (1992). "Comportement de chasse des orques (Orcinus orca) autour des iles Crozet." Canadian 

Journal of Zoology 70: 1656-1667. 

Hoelzel, A.R., G.A. Dover (1991). "Genetic differentiation between sympatric killer whale populations." 

Heredity 66: 191-195. 

Hoelzel, A.R., M. Dahlheim, S.J. Stern (1998). "Low genetic variation among killer whales (Orcinus orca) 

in the Eastern North Pacific, and genetic differentiation between foraging specialists." Journal of 

Heredity 89: 121-128. 

Matkin, C.O., G.M. Ellis, E.L. Saulitis, L.G. Barrett-Lennard, D.R. Matkin (1999). Killer Whales of 

Southern Alaska. Homer, Alaska, North Gulf Oceanic Society. 

Olesiuk, P.F., M.A. Bigg, G.M. Ellis (1990). "Life history and population dynamics of resident killer whales 

(Orcinus orca) in the coastal waters of British Columbia and Washington State." Report of the 

International Whaling Commission(Special Issue 12): 209-243. 

Similä, T., J.C. Holst, I. Christensen (1996). "Occurrence and diet of killer whales in northern Norway: 

seasonal patterns relative to the distribution and abundance of Norwegian spring-spawning 

herring." Canadian Journal of Fisheries and Aquatic Sciences 53: 769-779. 



30

Stevens, T.A., D.A. Duffield, E.D. Asper, et al. (1989). "Preliminary findings of restriction fragment 

differences in mitochondrial DNA among killer whales (Orcinus orca)." Canadian Journal of 

Zoology 67: 2592-2595. 

Visser, I.N., P. Mäkeläinen (2000). "variation in eye-patch shape of killer whales (orcinus orca) in new 

zealand waters." Marine Mammal Science 16(2): 459-469. 



31

Oral And Poster Presentations 

SOCIAL DETERMINANTS OF POPULATION STRUCTURE IN KILLER WHALES: 

INSIGHTS FROM ASSOCIATION PATTERNS, GENETICS AND ACOUSTICS. 

Barrett-Lennard L.G 

Vancouver Aquarium Marine Science Centre and University of British Columbia. P.O. Box 3232, 

Vancouver, B.C. V6B 3X8, Canada, Canada & University of British Columbia, Department of 

Zoology, 6270 University Blvd, Vancouver, B.C. V6T 1Z4, Canada, barrett@zoology.ubc.ca 

Seven distinct populations of killer whales have been identified off the coasts of British 

Columbia and southern Alaska. Three are fish-eating residents, three are mammal-eating 

transients, and one, offshores, have an unknown diet. Each population has from 75 to several 

hundred members, with the exception of one that is on the brink of extinction. Each of the 

resident populations shares its usual home range with one or more transient population and 

vice versa, but populations with the same feeding specializations overlap very little. The 

offshores partially overlap the range of both other types. This situation is illustrated 

schematically in Figure 1. 

Figure 1: Approximate range of resident, transient and offshore killer whales in the northeastern Pacific ocean. 

Despite their adjacent or overlapping distributions, members of different populations 

avoid close contact. No emigration between populations has been documented, and genetic 

analysis indicates that it is rare. This segregation into extremely small sympatric and 

parapatric populations has not been described in other highly motile animals and begs 

explanation. I hypothesize that it results from the concordance of four behavioural and 

ecological attributes, outlined below. 

1. Killer whales in the northeast Pacific have highly effective inbreeding avoidance 

systems. In residents, most matings occur between individuals that belong to the same 



32

population but that have markedly dissimilar acoustic repertoires (Barrett-Lennard, 

2000). Since relatedness and repertoire similarity are correlated, this mating system 

not only prevents incestuous matings but ensures that most occur between individuals 

that are less closely related than if mate choice was random. The mating systems of 

transients and offshores have not been described in detail, but allele frequency 

analysis suggest that they also achieve lower inbreeding levels than expected by 

random mating. Inbreeding avoidance within each killer whale population reduces the 

relative genetic benefits to individuals of dispersing between populations and allows 

smaller populations to be viable. 

2. Killer whales in the northeast Pacific live in an environment where prey are abundant 

and aggregated, but highly variable both spatially and temporally. Such an 

environment favours the transmission of information about the distribution of prey 

aggregations between related group members (Barrett-Lennard et al. 2001), which in 

turn benefits individuals that stay in their social groups. 

3. As long-lived, highly social animals, killer whales develop relationships not only 

within but between social groups. This allows linkages between social groups to 

develop, which may be reinforced and maintained by inter-group mating. These 

linkages may reduce inter-group conflict, improve access to resources, and provide a 

further advantage to individuals that remain in their natal populations compared to 

those that leave. 

4. Because water is an excellent conductor of sound and killer whales use group-specific 

calls, they have a reliable long-distance group identification system. This allows the 

social cohesion of physically-dispersed groups, and benefits groups that remain 

within acoustic contact over those that disperse widely. It also implies that killer 

whale populations are functional social units, vindicating Bigg’s description of them 

as “communities”. 

In combination, these factors reduce the competitive and genetic costs of non-dispersal 

experienced by most organisms and provide substantial benefits to remaining with kin for life. 

According to the hypothesis, population segregation is a natural consequence of limited 

dispersal. Population size, on the other hand, is likely a function of the frequency with which 

social groups associate, with fission occurring if the size and range of a population become 

such that some groups fail to encounter others at a threshold rate. 

The attributes of killer whales and their environment that predispose them to live in 

small, segregated populations may have evolved (both genetically and culturally) in response 

to the periodic events causing bottlenecks that might be expected to a top-level predator in a 

variable environment. However, the hypothesis does not preclude the possibility of 

coevolution. For example, the combination of the first three factors described above may 

have created strong selection pressure for the fourth. 

BIBLIOGRAPHY 

Barrett-Lennard, L. G. (2000). Population structure and mating patterns of killer whales 

(Orcinus orca) as revealed by DNA analysis. PhD thesis. University of British 

Columbia, Vancouver. 

Barrett-Lennard, L. G., V. B. Deecke, H. Yurk, J. K. B. Ford (2001). "A sound approach to 

the study of culture." Behavioral and Brain Sciences 24(2): 325-326. 



33

Bigg, M. A. (1982). "An assessment of killer whale (Orcinus orca) stocks off Vancouver 

Island, British Columbia." Report of the International Whaling Commission 32: 625- 

666. 



34

KILLER WHALES AT MARION ISLAND, SOUTHERN OCEAN 

M.N. Bester, M. Keith & P.A. Pistorius 

Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria, 

0002, South Africa. 

Marion Island (46°54’S, 37°45’E), the larger of the two islands within the Prince 

Edward Island group, is situated in the Southern Indian Ocean north of the Antarctic Polar 

Front. The island has an area of 296 km 2 and a circumference of approximately 72 km (Condy 

et al. 1978). Data on killer whales were collected on an opportunistic basis between 1973 and 

2000 by researchers operating within the South African National Antarctic Programme 

(SANAP) as described in Condy et al. (1978), Keith et al. (2001) and Pistorius et al. (2002). 

Spatial distribution - distance nearshore - Most killer whales sighted off Marion Island 

were predominantly in the nearshore area (Condy et al. 1978, Keith et al. 2001, Pistorius et al. 

2002). As southern elephant seal pups (Mirounga leonina) remain in near shore waters during 

play and local post-weaning dispersion (Lenglart & Bester 1982; Wilkinson & Bester 1990), 

and elephant seal females and penguins enter and exit the water here at the land-sea boundary, 

it is likely to be the most rewarding hunting area for killer whales (Keith et al. 2001; Pistorius 

et al. 2002). Especially newly weaned southern elephant seal pups would be prone to 

predation near the shore since Guinet et al. (1992) found a high predation rate of killer whales 

on weaned elephant seal pups at the Îles Crozet. Swimming speeds of killer whales patrolling 

the beaches varied between 11.9 km h -1 and 14.44 km h -1 (Pistorius et al. 2002). 

Distribution around Marion Island - The most sightings of killer whales were recorded 

around the base station (Keith et al. 2001) possibly due to the high number of potential 

observers present there. Observer activity also possibly led to an increase in sightings at some 

sites in the vicinity of eight to ten field huts, focal points of human activity, situated along the 

coast of Marion Island. However, prey distribution and availability may also play a definite 

role in the frequency of occurrence of observations around the island. The areas with high 

percentage frequencies of sightings away from the base area support colonies of penguins and 

elephant seals. By far the majority of breeding (and moulting) elephant seals occupy the 

eastern coasts (Wilkinson & Bester 1990). The consequent higher seal movement could 

explain the predominance of killer whales on the east coast. In addition, on 13 December 

2000, all of the 260 sightings of individuals which were recorded right around the island 

(Pistorius et al. 2002) were made from the four observation sites along the northeast coast, 

except one killer whale that was seen at Kildalkey on the southeast coast (Fig. 1). Despite the 

large number of fur seals (Arctocephalus tropicalis) residing on the west and north coasts of 

Marion Island (Hofmeyr et al. 1997), relatively few sightings of killer whales were recorded 

there. This might be related to the behaviour, distribution and difference in the seasonal 

haulout cycle of these two (of three) seal species found at Marion Island. 

Seasonal occurrence - The seasonal occurrence of killer whales at Marion Island (Keith 

et al. 2001) follows that recorded by Condy et al. (1978) and Guinet et al. (1992) where the 

maximum frequency of observations occurred in October, November and December, on 

Marion Island (Fig. 2) and Îles Crozet respectively. Condy et al. (1978) and Keith et al. 

(2001) further found a steep decline in number of sightings during January and February, with 

another, less pronounced, increase in sightings occurring during March to May. Roux (1986), 

on the other hand, found a clear seasonal cycle of occurrence at the temperate Amsterdam 

Island with killer whales being rare in July to August and more common in February to March 



35

(i.e. three to five months later than their peak in abundance around the sub-Antarctic islands). 

The observed difference in the timing of peak abundance in killer whales might be related to 

dispersing killer whales passing through different latitudes at different times (Mikhalev et al. 

1981). 

Group size - The overall mean group size for the whole study period was approximately 

four individuals (Keith et al. 2001; Condy et al. 1978). Elsewhere group sizes varied between 

1-15 individuals, with an average of three animals (Baird & Dill 1995), while Mikhalev et al. 

(1981) found the most frequent group size to be six to eight animals, although the numbers 

varied between one to several hundred animals. 

Sex and age composition - Adult females predominated (Keith et al. 2001) whereas 

Condy et al. (1978) calculated that killer whales had a sex/age composition of 28.7% adult 

males, 21.4% adult females, 24.7% subadults, 7.8% calves and an unidentified class of 17.4% 

at Marion Island. However, comparison between studies is complicated due to the difficulty in 

distinguishing between a subadult male and an adult female. 

Diurnal sighting frequencies - Killer whales were only observable from dawn to dusk 

with a peak of opportunistic observations during late afternoon (Condy et al. 1978; Keith et 

al. 2001), a probable result of increased human activity around the base station at that 

particular time of the day. The dawn-to-dusk surveys (DDUs), on the other hand, produced a 

relatively constant distribution of sightings throughout the day (Keith et al. 2001; Pistorius et 

al. 2002). 

Photogrammetry - The Defran et al. (1990) method for photogrammetry could only be 

used on a few individuals that did possess unique, useable markings. The Heimlich-Boran 

(1986) method suffered from the varied placing of a base line (BL), but the methods devised 

(Keith et al. 2001) provide a quantitative way to position the BL. It may only become evident 

after obtaining improved photographs, whether the proposed new adapted methods (Keith et 

al. 2001) will improve the photogrammetric analysis method of Heimlich-Boran (1986). 

Photo-identification - Many of the photographs of the killer whales were of poor quality 

and taken from a great distance which made reliable identification difficult (Keith et al. 

2001). The opportunistic and sporadic nature of photographing the killer whales at Marion 

Island precluded all of the killer whales being photographed. Due to the nature of the 

photographs, which concentrated on individuals, groups could not be distinguished from the 

photographs. One female with distinct markings on the dorsal fin, first identified in 1973, was 

still present around the island in 1993, at an age in excess of 20 years. 

Population size - We identified 26 whales in seven pods during the early morning to late 

afternoon sightings on the island-wide vigil (13 December 2000). A second method indicated 

that 29 individuals moved north past the base station between 15h28 and 17h55, while a third 

estimate of abundance suggested that 20 killer whales were seen in front of the base station, 

three at Archway, and three were seen at 16h02 approaching from the west at Pinnacles 

(Pistorius et al. 2002). Therefore, we think that there were between 25 and 30 killer whales 

hunting around Marion Island during their peak presence in early December 2000. 

Human impact - Marion Island has recently been proposed as an eco-tourism destination 

(Heydenrych & Jackson 2000) and killer whale ‘watching’ could become a realistic tourist 

attraction. Looking solely at the seasonal and diurnal pattern of the occurrences, “orca” 



36

watching from shore based vantage points could be a viable option in the peak season from 

October to December. If boat-based whale watching is ever implemented, care should be 

taken regarding contact with the killer whales as such an activity could have immediate 

behavioural effects as well as long term distribution adjustment effects (Corkeron 1995). 

Killer whales often take toothfish off longlines (Ashford et al. 1996) and the Marion Island 

summer population may be attracted to longline fishing activity, which officially commenced 

in 1996 in the vicinity of the Prince Edward islands. 

ACKNOWLEDGEMENTS 

Funding for research at Marion Island was provided by the Department of 

Environmental Affairs and Tourism, on the advice of the South African Committee for 

Antarctic Research (SACAR). 

REFERENCES 

ASHFORD, J.R., RUBILAR, P.S. & MARTIN, A.R. 1996. Interactions between cetaceans and 

longline fishery operations around South Georgia. Marine Mammal Science 12: 452-457. 

BAIRD, R.W. & DILL, L.M. 1995. Occurrence and behaviour of transient killer whales: seasonal and 

pod-specific variability, foraging behaviour, and prey handling. Canadian Journal of Zoology 

73: 1300-1311. 

CONDY, P.R., VAN AARDE, R.J. & BESTER, M.N. 1978. The seasonal occurrence and behaviour 

of killer whales Orcinus orca, at Marion Island. Journal of Zoology, London 184: 449-464. 

CORKERON, P.J. 1995. Humpback whales (Megaptera novaeangliae) in Hervey Bay, Queensland: 

behaviour and responses to whale-watching vessels. Canadian Journal of Zoology 73: 1290- 

1299. 

DEFRAN, R.H., SHULTZ, G.M. & WELLER, D.W. 1990. A technique for the photographic 

identification and cataloging of dorsal fins of the bottlenose dolphin (Tursiops truncatus). 

Report of the International Whaling Commission (Special issue 12): 53-55. 

GUINET, C., JOUVENTIN, P. & WEIMERSKIRCH, H. 1992. Population changes, movements of 

southern elephant seals in Crozet and Kerguelen Archipelagos in the last decades. Polar 

Biology 12: 349-356. 

HEIMLICH-BORAN, J.R. 1986. Photogrammetric analysis of growth in Puget Sound Orcinus orca . 

In: Behavioural biology of killer whales, (eds) B.C. Kirkecold & J.S. Lockard, Vol. 1, Alan R. 

Liss, Inc., New York. 

HEYDENRYCH, R. & JACKSON, S. 2000. Environmental impact assessment of tourism on Marion 

Island. Prince Edward Islands Management Committee, Department of Environmental Affairs 

and Tourism, South Africa. 

HOFMEYR, G.J.G., BESTER, M.N. & JONKER, F.C. 1997. Changes in population sizes and 

distribution of fur seals at Marion Island. Polar Biology 17: 150-158. 

KEITH, M., BESTER, M.N., BARTLETT, P.A. & BAKER, D. 2001. Killer whales (Orcinus orca) at 

Marion Island, Southern Ocean. African Zoology 36: 163-175. 

LENGLART, P.Y. & BESTER, M.N. 1982. Post-weaning dispersion of southern elephant seals 

Mirounga leonina underyearlings at Kerguelen. Revue de Ecologie (Terre et la Vie) 36: 175- 

186. 

MIKHALEV, Y.A., IVASHIN, M.V., SAVUSIN, V.P. & ZELENAYA, F.E. 1981. The distribution 

and biology of killer whales in the southern hemisphere. Report of the International Whaling 

Commission 31: 551-565. 

PISTORIUS, P.A., TAYLOR, F.E., LOUW, C., HANISE, B., BESTER, M.N., DE WET, C., DU 

PLOOY, A., GREEN, N., KLASEN, S., PODILE, S. & SCHOEMAN, J. 2002. Distribution, 

movement, and estimated population size of killer whales (Orcinus orca) at Marion Island, 

December 2000. South African Journal of Wildlife Research 32: 86-92. 

ROUX, J.-P 1986. Le cycle d’abondance des orques, Orcinus orca, aux îles Saint-Paul et Amsterdam. 

Mammalia 50: 5-8. 



37

WILKINSON, I.S. & BESTER, M.N. 1990. Duration of post-weaning fast and local 

dispersion in the southern elephant seal, Mirounga leonina, at Marion Island. Journal 

of Zoology, London 222: 591-600. 

N 

0% 

2km 

0% 

0% 

Mixed Pickle Cove 

0% 

0% 

Cape Davis 

Goodhope Bay 

4.8% 

0% 

Pinnacles 

16% 

Ship’s Cove 

Transvaal Cove (Base) 

Kildalkey Bay 

20% 

Archway Bay 

Figure 1. Observation points and percentage killer whale activity (black pie charts) recorded during 06h00 to 

18h00 observation on 13/12/2000 at Marion Island, and the percentage of elephant seal pups (grey pie 

charts) born at the main breeding beaches during the 2000 breeding season. 

8.3% 

0.5% 

14.2% 

12.1% 

10.7% 



5.1% 

8.3% 

14.5% 

14.5% 

38% 

7.0% 

0.4% 

25% 

38

Frequency of occurrence (%) 

5 

4,5 

4 

3,5 

3 

2,5 

2 

1,5 

1 

0,5 

0 

oct-73 

oct-74 

oct-75 

oct-76 

oct-77 

oct-78 

oct-79 

oct-80 

oct-81 

oct-82 

oct-83 

oct-84 

oct-85 

Months 

Figure 2. Percentage frequencies of observations of killer whales for the 1973-1996 study period at Marion 

Island. Data are represented on a monthly basis and were interpolated for months when no recordings were 

made. No data were available for the period October 1980 to November 1983. 

oct-86 

oct-87 

oct-88 

oct-89 

oct-90 



oct-91 

oct-92 

oct-93 

oct-94 

oct-95 

39

BEHAVIOR AND ECOLOGY OF KILLER WHALES IN MONTEREY BAY, 

CALIFORNIA 

Black N. 1 , Ternullo R. 2 , Schulman-Janiger A. 3 , Ellis G. 4 , Dahlheim M. 5 . 1,2 Peggy Stap 

Monterey Bay Cetacean Project, P.O. Box 52001, Pacific Grove, CA 93950 Nyblack@aol.com 3 

American Cetacean Society, Los Angeles 4 Canadian Department of Fisheries and Oceans 5 National 

Marine Mammal Laboratory, NOAA. 

INTRODUCTION AND BACKGROUND 

Monterey Bay (36°N 122°W) is located along the central California coast within a 

highly productive region of major upwelling. The Monterey Submarine Canyon is the most 

prominent bathymetric feature within the Bay and beyond, allowing for unique opportunities 

to study deep-water cetaceans in a near-shore environment. 

Three known ecotypes (Residents, Transients, Offshore) of Killer Whales exist in the 

eastern North Pacific, and all have been sighted in Monterey Bay. Each can be distinguished 

by appearance and vocalizations at sea and have been differentiated genetically. Resident 

whales, which are well studied in the Pacific Northwest, travel and feed in predictable areas 

during summer months in inland waters of Washington state, Vancouver, B.C., and Alaska. 

They prey primarily on fish, live in closely associated family groups, and are very vocal. 

Transients in Monterey Bay are part of the west coast community of about 300 whales that 

range from southern California to southeast Alaska, prey on marine mammals, travel in 

relatively small groups, travel over long ranges, and are often vocally quiet. The Offshore 

type is least known, often travels in large groups of over 100 animals, many have nicked fins, 

and probably prey on fish and squid. A fourth type that has occurred periodically in Monterey 

Bay is the “LA Pod”. No genetic samples have been obtained for this group, and they have 

never been seen in association with any other type. 

METHODS 

Our methods for reaching the killer whales included use of 55-70’ powerboats and a 22’ 

inflatable. The study period for this report extended from 1987 through 2002. Our effort was 

both opportunistic, on whale watch vessels, and dedicated searches for killer whales on 

special projects funded by the BBC and National Geographic Society and on our own vessels 

throughout the study period. In addition a large sighting network is in place where various 

vessels reported killer whale sightings. Our research methods included photo-identifying 

individual whales and documenting their behavior, sighting locations and local movement 

patterns as well as collaborating with other scientists in the Pacific to document re-sightings 

in other areas. 

RESULTS AND DISCUSSION 

Transients were most frequently sighted (223 sightings with photos from 1987-2002) 

and were highly associated with the canyon edge. Offshore (18 sightings) and LA Pod (9 

sightings) sightings were found along canyon edges and also in inshore shallower waters. 

Known prey of each killer whale type when feeding in Monterey Bay included for 

Transients: Gray whale calves, California sea lions, Harbor Seals, Elephant Seals, Dall’s 

Porpoise, Pacific White-Sided Dolphins, Long Beaked Common Dolphin, and seabirds; 

Offshores: salmon, small schooling fish, and blue shark; Residents: Chinook salmon; LA Pod: 



40

Great White Shark (north of Monterey off Farallon Islands; Pyle et al. 1997). Prey was nonoverlapping 

among types except both offshore and resident whales preyed on salmon. 

As of September 2002, number of individual whales identified for each type included 

145 transients, 172 offshores (min. numbers with 230 maximum), and 8 LA pod members. 

Within the transients, 36 were adult males, 7 females with no calves (over 10 sighting years), 

24 reproductive females, and 78 juveniles/females/calves. 

The Resident K and L Pods (part of southern Residents), which occur predictably during 

summer in Washington and Vancouver, were sighted once in Monterey Bay on January 29, 

2000. This represents a distance of 1,251 km from their known summer range. During this 

day the whales foraged on Chinook salmon. This unusual event could represent declining 

food sources to the north and the whales' search for abundant prey elsewhere. 

LA Pod whales ranged from San Francisco (central California) to the upper Sea of 

Cortez, with individual movements of 2,847 km. These whales were frequently sighted off 

Los Angeles, CA during the 1980’s and a few times in Monterey during late 1980’s and 

1990’s. They occurred off the West Coast of Baja and Sea of Cortez during this period as 

well. These whales were last sighted in December 1997 off San Diego, CA and may currently 

be residing in Mexico. Largest group size documented for these whales was 13, which is the 

known population for these individuals. 

The Offshore whales traveled the longest distance for any Killer Whale type in the 

Pacific, with individuals sighted in Los Angeles, Monterey Bay and off Kodiak Island, 

Alaska, a distance of 3,680 km. Group sizes of these whales while in Monterey Bay differed 

seasonally. During winter months mean group size was 52 with maximum group size around 

200 whales. Only one sighting occurred during spring with 22 whales, and during 8 sightings 

in fall, group sizes were small with a mean of 10 whales. No sightings occurred during 

summer, but offshores were sighted in British Columbia and Alaska during this period. 

Transient whales were more frequently sighted in Monterey Bay compared to other 

types and therefore, more information has been gathered on them. The discovery curve of new 

adult male and female whales identified beginning in1987 slowly increased until 1999 where 

it leveled off, assuming now that most adults in this population that travel through and feed in 

Monterey have been identified. 

Transient whales sighted in Monterey Bay have been identified from southern 

California to Southeast Alaska, with sightings within California, along the outer coasts of 

Oregon, Washington, British Columbia, and one sighting in inland waters of Southeast 

Alaska. The longest-range movement of four whales occurred from Monterey to Southeast 

Alaska, a distance of 2,594 km. Occurrence varied by season, with peak occurrence during 

spring and fall and few sightings during summer. Of the whales identified in Monterey and resighted 

to the north, 12 were sighted off Washington, B.C., and Alaska during summer 

months. Group size also varied by season, with the largest groups occurring during spring and 

smallest in summer. Many of the larger groups (32 was largest) were temporary associations 

of smaller subgroups over a day. Ninety-five percent of all identified whales were sighted in 

spring months over combined years. Whales that are rarely sighted were present more often 

during spring months and frequently sighted whales occurred more often during spring 

compared to other months. The higher occurrence, group sizes, and individual whale presence 

during spring corresponded with the migration of Gray Whale cow/calves through the Bay. 

The low sightings in summer could be due to Killer Whales shifting north with the pulse of 

mother/calf Gray Whales. As one example, an adult female sighted in Monterey on several 

occasions was also seen attacking a gray whale calf off Vancouver Island during summer. 

Of the 24 documented reproductive females, 13 were sighted frequently enough to 

determine calving intervals. Since some whales may not be sighted for many months, there 

was a bias that calves may have been born and died before their mothers were re-sighted. 



41

Given this, years between calves ranged from 3 (n=1) to 12 (n=1) years; and in between: 4 

years (n=1), 5 yr (n=1), 6 yr (n=2), 7 yr (n=3), 8 yr (n=3), 9 yr (n=1). Compared to other 

populations this rate appeared low and could be related to high levels of PCB’s found in this 

group of killer whales. 

Association pattern analysis indicated that transient whales occurred in 18 core groups 

of frequently sighted whales (up to 36 if infrequently sighted whales were included). Core 

groups were usually composed of 2-4 reproductive females with juveniles and calves, and 

some with one sprouter male or adult male. A few groups were composed of male pairs. 

These core groups of individuals were sighted together on more than 80% to 100% of the 

time. Two or more of these core groups joined together for temporary associations, especially 

during spring months while searching for and hunting Gray Whale calves. Three welldocumented 

young males were sighted over a period of 10 and 11 years and are now sprouters 

and young adults. All still travel with their probable mothers with estimated current ages of 15 

to 19 years. 

This study represents the only long-term database for Killer Whales south of 

Washington State but part of the same population as whales to the north. Monterey Bay is a 

key area for detailed studies of the three known ecotypes and possibly five, as the ranges of 

these types may overlap in the region. 

Study Area 

2000 

1500 

Depth in Meters 

Mont erey Submarine Canyon 

5 km 

Santa Cr uz 

Car mel Cany on 

122°20'W 122°00'W 

N 

n=140 transient sightings 

n=12 offshore sightings 

n=9 LA pod sightings 

1000 

500 

200 

Pt. 

Pinos 

Hopkins 

Cypr ess Pt. 

Pt. Lobos 

100 50 

Gr anite Canyon 

Pt. Sur 

37°00'N 

Monter ey 

Moss 

Landing 

36°40' 

N 

36°20'N 

Figure 1. Distribution of Killer Whale types in Monterey Bay. 



42

white shark attack 1997 

40° 

30° 

8 

20° 

(Pyle et al.) 

50° 

40° 

145 

30° 

20° 

3 

last sighted 12/3/97 

Farallon Is. 

5 

8 

8 

Is. Cedros 

Monterey Bay 

Santa Barbara, CA 

Los Angeles, CA 

San Diego, CA 

5 

2,687 km 

2 

Canal de Ballenas, MX 

Figure 2. Distribution of LA Pod. 

27 

5 

1 

20 

4 

Farallon Is. 

5 

3 

Channel Is. 

4 

Catalina Is. 

0 

Southeast Alaska 

Queen Charlotte Is., B.C. 

Vancouver Is., B.C. 

Olympic Pen, WA 

Coos Bay, OR 

Monterey Bay 

2,594 km 



Baja California, MX 

Figure 3. Distribution of Transients 



43

50° 

40° 

164 

30° 

20° 

4 

3 

Kodiak Is. Alaska 

23 

2 

3 

3 

Farallon Is. 

Coos Bay, OR 

Monterey Bay 


24 


0 

Southeast Alaska 

British Columbia 

Baja California, MX 

180-230 Identified off California 

as of 2002 

3,680 km 

Figure 4. Distribution of Offshores 



44

KILLER WHALES (ORCINUS ORCA) OF ALASKA: GULF OF ALASKA TO THE 

BERING SEA. 

Dahlheim M.E. 1 , Ellifrit D.K. 2 , Hoelzel A.R. 3 , DeLeuw R. 1 . 

1 Alaska Fisheries Science Center, National Marine Mammal Laboratory, 7600 Sand Point Way, 

Seattle, Washington 98115; marilyn.dahlheim@noaa.gov; 2 Center for Whale Research, 1359 

Smuggler’s Cove Road, Friday Harbor, Washington 98250; 3 Dept. of Biological Sciences, Durham 

University, United Kingdom; 

The documented decline of Steller sea lions, harbor seals, and sea otters in the western 

Gulf of Alaska and Bering Sea has raised questions about the potential impact that killer 

whale predation may have on these populations. Predator population size is a key factor when 

determining impacts on prey populations. Although killer whale population size and stock 

structure is well documented for the waters of Southeast Alaska and Prince William Sound, 

this is not so for killer whales inhabiting the waters west of Kodiak Island to the Bering Sea. 

The first dedicated killer whale surveys in this area occurred in 1992 and 1993 where 

minimum counts of killer whales were obtained through photo-identification studies. 

Analyses of photographic data from both the dedicated surveys and fishery observer program 

(1980 to 2001) have resulted in the identification of approximately 400 individual killer 

whales. In 2001, a dedicated killer whale survey was completed in the waters from Kodiak 

Island west to the Eastern Aleutian Islands. In addition to the photo-identification study, killer 

whale biopsy samples were collected to enable us to identify resident, offshore, or transient 

eco-types. Based on the 2001 surveys, we have added approximately 240 whales to our 

photographic database. We have confirmed the presence of all three eco-types in this Alaskan 

region. At least 100 of these Alaskan killer whales have been seen multiple times over a 10year 

period allowing us to track movements of individual whales. In addition, resident killer 

whales from Southeast Alaska, Gulf of Alaska, and Bering Sea have been documented 

together linking killer whales throughout Alaskan waters. Offshore whales were found south 

of Kodiak Island, resulting in the northern most sighting of this eco-type. 



45

A REVIEW OF KILLER WHALES (ORCINUS ORCA) IN BRAZILIAN WATERS 

Dalla Rosa, Luciano 1 , E.R. Secchi 1,2 , J. Lailson-Brito Jr. 3,4 and A.F. Azevedo 4,5 

1 Marine Mammals Laboratory, Museu Oceanográfico “Prof. Eliézer C. Rios”, Fundação Universidade 

Federal do Rio Grande, Cx. Postal 379, Rio Grande, RS, Brazil, 96200-970. e-mail: pgobldr@furg.br 

2 Marine Mammals Research Team, University of Otago, PO Box 56, Dunedin, New Zealand. 

3 Projeto MAQUA – Depto. Oceanografia / Universidade do Estado do Rio de Janeiro, Rio de Janeiro, 

RJ, Brazil. 

4Laboratório de Radioisótopos EPF - IBCCF, Universidade Federal do Rio de Janeiro, Rio de Janeiro, 

RJ, Brazil. 

5 PPGB/IBRAG - Departamento de Ecologia - Universidade do Estado do Rio de Janeiro, Rio de 

Janeiro, RJ, Brazil. 

INTRODUCTION 

• Information on killer whales in Brazilian waters is still limited and based mostly on 

sporadic sightings and strandings. 

• In this study, we review the available literature and present new information on the 

occurrence, distribution and ecology of killer whales in Brazilian waters. 

METHODS 

Data were obtained from: 

• Scientific literature; 

• Unpublished information acquired from colleagues, museums and the media 

(newspapers and TV); 

• Information along with photographs donated by the public, including fishermen; 

• Personal observation during non systematic beach surveys or research cruises. 

RESULTS 

• The species has been recorded along the entire Brazilian coast, except for coastal 

waters of the northern region (Fig. 1). The southernmost records are near the border 

with Uruguay, while the northernmost is 10nm from St. Peter and St. Paul's 

Archipelago (00 o 55’N; 29 o 20’W). 

STRANDINGS 

• Strandings were concentrated on the southern region, where they occurred mostly in 

spring and summer (Tab. 1). From 20 known strandings, 16 occurred on the southern 

coast, 14 of which in Rio Grande do Sul State. 

• The largest measured specimen was a 6.21m long female found in Cabo Frio, RJ. Two 

animals that stranded in the southern region were calves, one estimated as 

approximately 2.60m long. Sex was determined for nine specimens: six females and 

three males. 

SIGHTINGS 

• Sightings were reported for all seasons. Sighting positions are plotted in Fig. 1, and 

include 29 new records, 19 in coastal waters of Rio de Janeiro State (RJ). Additional 



46

sightings for RJ were obtained from Lodi and Hetzel (1998) and Siciliano et al. 

(1999). Other sources of sightings include Castello and Pinedo (1986), Best et al. 

(1986) and Secchi and Vasque Jr. (1998). Sightings not plotted due to lack of detailed 

information include those of Antonelle et al. (1987), regarding animals sighted off 

Paraíba State (6 o 29’S to 7 o 33’W) from 1980-1985, and those of Budylenko (1981) and 

Mikhalev et al. (1981), for southern and northeastern-southern Brazil, respectively. 

• In the southeastern region, sightings were concentrated during spring and summer 

months along coastal waters. 

• In the southern region, most records are from winter and spring months and in 

offshore waters, where killer whale interactions with longline fisheries are common. 

• One adult male photographed at Ilha Grande Bay (RJ) in September 1993 was 

resighted five months later at Ubatuba (SP), ca. 100km from the first location. 

DIET 

• Stomach contents from 8 animals have been analyzed. A variety of prey items were 

recorded: bony fish (weakfish, Cynoscion guatucupa), elasmobranchs (eagle stingray, 

Myliobatis sp.), cetaceans (Burmeister’s porpoise, Phocoena spinipinnis; franciscana, 

Pontoporia blainvillei), cephalopods (Suborder Oegopsida) and salps (Iasis zonaria) 

(Castello, 1977; Dalla Rosa, 1995; Ott and Danilewicz, 1996). 

• Killer whales also prey on: tunas (Thunnus spp.) and, mainly, sworfish, Xiphias 

gladius, caught by the longline fishery off southern and southeastern Brazil (Dalla 

Rosa, 1995; Secchi and Vasque Jr., 1998); manta rays, Manta birostris (Lodi and 

Hetzel, 1998). 

HUMAN IMPACTS 

• Six individuals were captured by Soviet pelagic fleets from 1969/70-1978/79 between 

10 and 20 o S (Mikhalev et al., 1981); 

• In February 1975, a female killer whale was incidentally captured on a beach seine at 

Cassino Beach, southern Brazil; 

• In July 1994, a female orca was incidentally caught in a monofilament longline off 

southern Brazil, but escaped alive (Dalla Rosa, 1995); 

• Harpooning and shooting have also been reported by longline fishermen. 

DISCUSSION 

• Most records are from the southeastern and southern regions. Although higher 

densities might be expected in temperate than in tropical waters, the lower research 

efforts in the northeastern and, especially, northern region could have accentuated the 

lack of information for these areas. 

• Occurrence of killer whales in coastal waters of Rio de Janeiro is seasonal (Lodi and 

Hetzel, 1998; Siciliano et al., 1999). In other areas, however, additional information is 

necessary to draw any conclusions. Summer and autumn surveys would help to verify 

if occurrence is seasonal in offshore waters of southern Brazil. 

• The same killer whale population possibly occurs in southern Brazil, Uruguay and 

northern Argentina, as suggested by the saddle patch pigmentation pattern (Iñiguez et 

al., 1994) and the interactions with longline fisheries. Further photo-identification and 

genetic studies are urged to determine the population identity of killer whales in the 

southwest Atlantic. 



47


We wish to thank Projeto Baleia Jubarte-Abrolhos, GEMARS, Marcos C.O. Santos, 

Hugo P. Castello, Paulo H. Ott, Lisandro Almeida, Regina Zanellato, Bia Hetzel, Fábio C.S. 

Costa and all other contributors who kindly shared information. 

REFERENCES 

Antonelle, H.H., Lodi, L. and Borobia, M. 1987. Avistagens de cetáceos no período de 1980 a 1985 no litoral da 

Paraíba, Brasil. In: Reunião de Especialistas em Mamíferos Acuáticos da América do Sul, 2., Rio de Janeiro, 

August 4-8, 1986. Anais: resumos. p.114. 

Budylenko, G.A. 1981. Distribution and some aspects of the biology of killer whales in the South Atlantic. Rep. 

int. Whal. Commn 31: 523-525. 

Castello, H.P. 1977. Food of a killer whale: eagle sting-ray, (Myliobatis) found in the stomach of a stranded Orcinus 

orca. Sci. Rep. Whales Res. Inst., 29: 107-111. 

Castello, H.P. and Pinedo, M.C. 1986. Sobre unos avistages en el mar de distintas espécies de cetáceos en el sur de 

Brasil. In: Reunión de Trabajo de Especialistas en Mamíferos Acuáticos de América del Sur, 1., Buenos Aires, 

25-29 junio, 1984. Actas. pp 61-68. 

Dalla Rosa, L. 1995. Interações com a pesca de espinhel e informações sobre a dieta alimentar de orca, Orcinus 

orca Linnaeus 1758 (Cetacea, Delphinidae), no sul e sudeste do Brasil. Rio Grande, 40p.(Bachelor thesis) 

Iñiguez, M.A., Secchi, E.R., Tossenberger, V. and Dalla Rosa, L. 1994. Orcas, Orcinus orca, en la Argentina y 

Brasil: informe preliminar (Orcas in Argentina and Brazil: preliminary report). In: Reunião de Trabalho de 

Especialistas em Mamíferos Aquáticos da América do Sul, 6., Florianópolis, 24-28 outubro. Resumos. p. 

103. 

Lodi, L. and Hetzel, B. 1998. Orcinus orca (Cetacea; Delphinidae) em águas costeiras do Estado do Rio de Janeiro. 

Bioikos 12(1): 46-54. 

Mikhalev, Y.A., Ivashin, M.V., Sausin, V.P. and Zelemaya, F.E. 1981. The distribution and biology of killer whales 

in the Southern Hemisphere. Rep. int. Whal. Commn 31: 551-566. 

Ott, P.H. and Danilewicz, D. 1996. Presence of franciscanas (Pontoporia blainvillei) in the stomach of a killer 

whale (Orcinus orca) stranded in southern Brazil. Mammalia 62(4): 605-609. 

Secchi, E.R. and Vaske JR., T. 1998. Killer whale (Orcinus orca) sightings and depredation on tuna and swordfish 

longline catches in southern Brazil. Aquatic Mammals, 24(2): 117-122. 

Siciliano, S., Lailson Brito Jr., J. and Azevedo, A.F. 1999. Seasonal occurrence of killer whales (Orcinus orca) 

in waters of Rio de Janeiro, Brazil. Z. Säugetierkunde 64: 251-255. 



48

Figure 1. Sightings (o) and strandings (+) of killer whales along the Brazilian coast. 



49

SIGHTINGS OF KILLER WHALES OFF THE ANTARCTIC PENINSULA FROM 

1997/98 TO 2001/02 

Dalla Rosa, L. 1 , Danilewicz, D. 2 , Bassoi, M. 3 , Moreno, I.B. 2 , Santos, M.C.O. 4 & Flores, P.A.C. 5 

1 Projeto Baleias/Brazilian Antarctic Programme, Marine Mammals Laboratory, Museu 

Oceanográfico “Prof. Eliézer C. Rios”, Fundação Universidade Federal do Rio Grande, Cx. Postal 

379, Rio Grande, RS, 96200-970, Brazil. E-mail: pgobldr@furg.br 

2 Grupo de Estudos de Mamíferos Aquáticos do Rio Grande do Sul (GEMARS), Rua Felipe Neri, 

382/203, Porto Alegre, RS, 90440-150, Brazil. 

3 School of Ocean and Earth Science, Southampton Oceanography Centre, European Way, SO14 3ZH, 

Southampton, United Kingdom. 

4 Instituto de Biociências, Universidade de São Paulo, Rua do Matão 321, São Paulo, SP, 055088-900, 

Brazil. 

5 International Wildlife Coalition Brazil, Cx. Postal 5087, Florianópolis, SC, 88040-970, Brazil. 

INTRODUCTION 

Killer whales, Orcinus orca, are a common species around Antarctic waters (e.g. Jehl 

et al., 1980; Mikhalev et al., 1981), however information on their abundance, distribution, 

population identity and taxonomic status remains to be better assessed. Mikhalev et al. (1981) 

proposed a new species of killer whale, Orcinus nanus, for the Southern Hemisphere, based 

on morphological and biological data. Berzin and Vladimirov (1983) also proposed a new 

species of killer whale, Orcinus glacialis, for Antarctic waters, based on morphological and 

ecological differences in relation to O. orca. Both proposals probably refer to the same 

population of smaller individuals. Antarctic killer whales commonly present lighter 

pigmentation with a conspicuous dorsal “cape” (Jehl et al., 1980; Thomas et al., 1981; Evans 

et al., 1982). 

Since the 1997/98 austral summer, the Projeto Baleias/Brazilian Antarctic 

Programme (PROANTAR) has conducted ship surveys in the Antarctic Peninsula region with 

the following objectives: (1) photo-identify humpback whales for comparison with 

international catalogues; (2) biopsy humpback whales for DNA and pollution analyses; (3) 

determine cetacean distribution and density estimates; and (4) record all cetacean sightings. In 

this paper we present data on killer whales observed off the Antarctic Peninsula in the 

summer seasons of 1997/98 through 2001/02. 

MATERIAL AND METHODS 

During five consecutive summer seasons (1997/98 – 2001/2002), cetacean research 

was conducted in the waters of the Antarctic Peninsula region, especially in the Gerlache and 

Bransfield Straits, from the 75m Oceanographic and Supply Ship (NApOc) ‘Ary Rongel’. In 

the Gerlache Strait, cetacean dedicated surveys were performed for distribution studies and 

density estimates. A total of 20 transects were performed. Whale search was made with naked 

eye and with 7X50 binoculars. The observers watched from the exterior wing bridges 

approximately 14m above sea level. Data recorded on the killer whales included date, time, 

coordinates, pod size/composition and behavior. Whenever possible, individuals were photoidentified 

from the ship or from a small inflatable boat, following Bigg et al. (1987). 



50


Sightings 

Overall, killer whales were the third most frequently sighted cetacean species in the 

region, after humpback and minke whales. A total of 41 sightings were registered (Fig. 1). 

Twenty-seven sightings (66%) occurred in the Gerlache Strait, where cetacean dedicated 

surveys were performed. Killer whale encounter rates in the Gerlache Strait ranged from zero 

to 0.37 individual per nautical mile, with an average of 0.10 (CV = 125%; n = 20 surveys), 

while humpback and minke encounter rates averaged 0.46 (CV = 90%) and 0.09 (CV = 

115%), respectively. Group size estimates varied from 1 to about 35 individuals ( X = 9.32; 

SD = 7.50), with larger groups composed of two or more subgroups. Calves were present on 

at least 61% of the sightings. 

Pigmentation pattern/Photo-identification 

The overall gray pigmentation with a conspicuous dorsal “cape” (Fig. 2) was observed 

on all but one of the closer encounters, suggesting that it is the predominant pattern off the 

Antarctic Peninsula. The existence of groups with different levels of lighter pigmentation 

could not be discarded. The strikingly distinctive coloration pattern of these Antarctic killer 

whales may be indicative of a specialized population (among ice floes, this light coloration 

might help to improve feeding efficiency, serving as a camouflage against prey) and, possibly, 

even a new species. Genetic and photo-identification studies are necessary to assess their 

taxonomic status and population identity. The yellowish hue due to diatom deposits was also 

observed, in varying amounts, on most encounters, including the one where the animals did 

not present a visible dorsal “cape”. The exception were some of the distant sightings, when 

animals might have presented this pigmentation but it could not be seen. 

Twenty-five killer whales have been photo-identified. Due to the overall lighter 

pigmentation, body scars are usually conspicuous and may be useful on individual 

identification, however care must be taken as at least some of the marks may not be 

permanent. 

Interactions with other marine mammals 

Killer whales were observed approaching and encircling humpback whales on four 

occasions, and a group of minke whales once, however no effective predation was observed. 

According to Dolphin (1987) and Jefferson et al. (1991), non-predatory interactions between 

killer whales and other marine mammal species are relatively common. On the other hand, 

predatory interactions may last for hours, making it more difficult to witness the whole event. 

During two consecutive sightings made on 4 December 1997, near the Elephant Island 

(61 o 26’S-55 o 00’W and 61 o 24’S-54 o 60’W), killer whales were seen throwing seals into the air 

with the tail flukes, possibly leopard seals, Hydrurga leptonyx. This type of behavior has also 

been observed in Peninsula Valdés (Iñiguez, 1993) and in Alaska (Dolphin, 1987). Killer 

whales were also seen chasing and presumably feeding on fur seals, Arctocephalus gazella, on 

1 March 2001 in the Schollaert Channel (64 o 31’S – 62 o 46’W). Killer whale tooth rake marks 

were present on about 4% of the flukes of humpback whales photo-identified in the Antarctic 

Peninsula region (n = 300). Katona et al. (1980) report that 33% of the humpbacks photoidentified 

in the western North Atlantic presented such scars. 



51


The Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) provided 

the financial support. SECIRM/Brazilian Navy provided the logistical support. We also wish 

to thank Paul Kinas, Eduardo Secchi, Glauco Caon, Alexandre Zerbini, Márcio Martins and 

Paulo Ott for help during the course of this study. 

REFERENCES 

Berzin, A.A. and Vladimirov, V.L. 1983. A new species of killer whale (Cetacea, Delphinidae) from 

Antarctic waters. Zool. Zh. 62(2): 287-295 [traduzido por S. Pearson]. 

Bigg, M.A., EllisG.M., Ford, J.K.B. and Balcomb, K.C. 1987. Killer whales – A Study of their 

Identification, Genealogy and Natural History in British Columbia and Washington State. Phantom Press and 

Publishers, Nanaimo, British Columbia, 79p. 

Dolphin, W.F. 1987. Observations of humpback whale (Megaptera novaengliae) - killer whale (Orcinus 

orca) interactions in Alaska: comparison with terrestrial predator-prey relationships. Can. Field-Nat. 101(1): 

70-75. 

Iñiguez, M.A. 1993. Orcas de la Patagonia Argentina. Buenos Aires, Propulsora literaria. 88p. 

Jefferson, T.A., Stacey, P.J. and Baird, R. 1991. A review of killer whale interactions with other marine 

mammals: predation to co-existence. Mamm. Rev. 21(4): 151-180. 

Jehl, J.R., Evans, W.E., Awbrey, F.T. and Drieschmann, W.S. 1980. Distribution and geographic 

variation in the killer whale (Orcinus orca) populations of the Antarctic and adjacent waters. Antarctic Journal of the 

United States 15(5): 161-163. 

Katona, S., Harcourt, P.M., Perkins, J.S. e Kraus, S. 1980. Humpback whales of the western North 

Atlantic: a catalog of identified individuals. 2 nd Ed., College of the Atlantic, Maine. 169p. 

Mikhalev, Y.A., Ivashin, M.V., Sausin, V.P. and Zelemaya, F.E. 1981. The distribution and biology of 

killer whales in the Southern Hemisphere. Rep. int. Whal. Commn 31: 551-566. 

Thomas, J.A., Leatherwood, S., Evans, W.E. and Jehl, J.R. 1981. Ross sea killer whale distribution, 

color pattern and vocalizations. Antarctic Journal of the United States 16: 157-158. 

Fig. 1 - Study area and killer whale sighting locations off the Antarctic Peninsula. 



52

Fig. 2 - The overall gray pigmentation is characteristic of most killer whales from the Antarctic 

Peninsula region. 



53

CLICK CHARACTERISTICS OF KILLER WHALES FEEDING ON NORWEGIAN 

SPRING-SPAWNING HERRING 

Damsgård, B. 1 , Similä, T. 2 & Leyssen, T. 3 

1) Fiskeriforskning, 9291 Tromsø, Norway; borge.damsgaard@fiskforsk.norut.no 

2) NORCA, Box 181, 8465 Straumsjøen, Norway; iolaire@online.no 

3) NORCA, Rozenlaan 8, 3650 Dilsen-Stokkem, Belgium; teoleyssen@hotmail.com 

ABSTRACT 

During the period 1998-2001 we recorded sounds from killer whales, Orcinus orca, 

feeding on Norwegian spring-spawning herring, Clupea harengus, during the winter season in 

the coastal waters of northern Norway. The study revealed that most click series used during 

feeding were broadbanded and with relatively few clicks (mean 13.2 clicks) and short click 

intervals (mean 69 ms). 

INTRODUCTION 

The use of underwater sounds play a key role in the feeding behaviour of many marine 

mammals. Killer whales have a large acoustic variation, including pulsed sounds, tonal 

whistles and short clicks (Ford 1989). Pulsed sounds are probably used for calls and 

communication, while clicks are directional forward-projected sounds with high intensities. It 

is well known that killer whales like other odontocetes may echolocate, but the mechanisms 

and ecological functions of clicking whales in the wild are still only partly described. Clicks 

of resident and transient killer whales in British Columbia, Canada, are well documented by 

Barrett-Lennard et al. (1996), while whales from other parts of the world are only anecdotally 

described. 

In the present study we describe click characteristics from killer whales in Vestfjorden, 

northern Norway (Similä & Ugarte, 1993), feeding on Norwegian spring-spawning herring. 

The recordings were conducted during hunting, herding and ‘carousel’ feeding of killer 

whales. 

MATERIALS AND METHODS 

The portable equipment was based on Brüel & Kjær hydrophones (8103 and 8105), a 

Nexus amplifier (Copenhagen, Denmark), and a DAT-recorder (Sony TCD-D100). One 

channel was frequency modulated (Pettersson D200, Uppsala, Sweden), enabling us to 

simultaneously record audio range sounds and high frequency sounds up to 100 kHz. 

Of totally approx. 8 h recordings we selected 329 sounds (with approx. 4200 clicks) 

based on the following criteria: The recordings should have a low background noise and no 

overload, and the sounds should be complete series of clicks that could be separated from 

other click series. Numbers of clicks, total time, click intervals (accuracy < 0.1 ms) and 

frequency range were analysed, using Avisoft SAS-Lab (Berlin, Germany). 

RESULT AND DISCUSSION 

The study revealed that most click series used during feeding were broadbanded and 

with relatively few clicks and short click intervals. The click series consisted of 2-109 clicks, 

with a mean of 13.2 clicks per sound. Most of the click series (62%) had less than 10 clicks. 

The mean total time was 0.59 s (range 0.05-6.7 s), and most of the click series (70%) lasted 

less than 0.5 s. In comparison, fish eating resident killer whales in Canada produced on 



54

average click sounds with 51 clicks and a total time of 7.2 s, while mammal eating transient 

killer whales on average used 17 clicks and a total time of 2.8 s (Barrett-Lennard et al., 1996). 

The click interval ranged from 6 ms to 750 ms, with a mean click interval of 69 ms, 

which corresponds to a click rate of 14.5 s -1 . In comparison the resident and transient killer 

whales in British Columbia had a mean click rate of 7.1 and 6.1 s -1 , respectively (Barrett- 

Lennard et al., 1996). 

In some click sounds the click interval were constant, while other sounds had a variable 

click interval. The sound in Fig. 1 A had more than 100 clicks and a click interval of 9.6 ms 

that remains nearly constant throughout the sound. Each single click had a double structure 

with a constant peak to peak interval of 0.32 ms. The click sound in Fig. 1 B and C are the 

high and audio component of the same sound. The click interval varies from 26 to 119 ms, 

and each click had a single click structure. Canadian click sounds did also have constant or 

variable click intervals (Barrett-Lennard et al., 1996), but the ecological significance of these 

acoustic features is still unknown. A killer whale may echolocate differently depending on 

whether it have a specific target or not, or the whale may use clicks for several ecological 

purposes. 

Frequency (kHz) 

20 

15 

10 

5 

0 

100 

50 

0 

20 

15 

10 

5 

0 

0.2 0.4 0.6 0.8 1 

0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 

Low frequency 

0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 

Time (seconds) 

A) 

High frequency 

Figure 1. Examples of clicks from killer whales feeding on herring in Norway. A) A click sound with short and 

constant click intervals; B) High frequency component of a click sound with long and variable click intervals 

(frequency limits between the two dotted lines); and C) Audio frequency component of sound B. 

Experimental studies of bottlenose dolphin, Tursiops truncatus, have clearly 

demonstrated the relationship between click intervals and distance between the whale and its 

target (Au & Nachticall, 1997). If the whale active listen to each click before emitting the next 

click, and if we assume that the processing time lag before the next click is 20 ms (Au & 

Nachticall, 1997), the click intervals in the present study indicate distances less than 40 m 

between the whale and the herring. If so, killer whales feeding on herring use clicks within a 

visible range between predators and prey. However, click intervals may also vary with other 

factors such as difficulties in detecting a target, or the present or absent of a target of interest 

(Au & Nachticall, 1997). The longest click interval in the present study (750 ms) correspond 

with a distance of more than 500 m. On the other hand, whales such as beluga, 



B) 

C) 

55

Delphinapterus leucas, probably emit long series of clicks without listening to each single 

click (Turl & Penner, 1989), and it is not possible to rule out the possibility of the same 

mechanism in killer whales feeding on herring. 

An analysis of the frequency range of each click revealed that most clicks were 

broadbanded, covering both the audio range and the high frequency range. The result indicate 

that many clicks had an energy peak between 20 and 30 kHz, while some of the energy 

ranged to 80-100 kHz. This corresponds well with the audiogram for killer whale, which 

range from 1 to 100 kHz, with a maximum hearing ability of approx. 20 kHz (Szymanski et 

al., 1999). In the sound example in Fig. 1 B and C, the frequency range were between 4 and 

86 kHz, with a peak energy about 22 kHz in the beginning of the sound. Frequency 

distribution is dependent of the distance between the hydrophone and the animal, and the 

position of the animal (Au & Nachticall, 1997), and the changes in frequencies during the 

sound may be due the movement of the whale. 

The study raises questions about the ecological function of clicks during feeding in 

killer whales. The click intervals and underwater observations indicate that most of the sounds 

are produced within the visible range of their preys. Independent of the question whether 

herring may hear high frequency sounds (Astrup, 1999), the fish may easily hear the low 

frequency component of the sound. One might speculate if the whales use clicks only for 

echolocation or in addition for other purposes. 

In summery, the study indicated that click series may play an important ecological role 

when killer whales feed on herring, potentially both as an close range echolocation and as an 

behavioural herding of fish in smaller groups. 

REFERENCES 

Astrup, J., 1999. Ultrasound detection in fish – a parallel to the sonar-mediated detection of 

bats by ultrasound-sensitive insects? Comp. Biochem. Physiol. 124: 19-27. 

Au, W.W.L., & Nachtigall, P.E., 1997. Acoustics of echolocating dolphins and small whales. 

Mar. Freshw. Behav. Physiol. 29: 127-162. 

Szymanski, M.D., Bain, D.E., Kiehl, K., Pennington, S., Wong, S. & Henry, K.R., 1999. 

Killer whale (Orcinus orca) hearing: Auditory brainstem response and behavioral 

audiograms. J. Acoustic Soc. Am. 106: 1134-1141. 

Barrett-Lennard, L.G., Ford, J.K.B. & Heise, K.A., 1996. The mixed blessing of echolocation: 

differences in sonar use by fish-eating and mammal-eating killer whales. Anim. Behav. 

51: 553-565. 

Ford, J. K.B., 1989. Acoustic behavior of resident killer whales (Orcinus orca) off Vancouver 

Island, British Columbia. Can. J. Zool. 67: 727-745. 

Similä, T. & Ugarte, F., 1993. Surface and underwater observations of cooperatively feeding 

killer whales in Northern Norway. Can. J. Zool. 71: 1494-1499. 

Turl, C.W. & Penner, R.H., 1989. Differences in echolocation click patterns of the beluga 

(Delphinapterus leucas). J. Acoustic Soc. Am. 68: 497-502 



56

THE BC CETACEAN SIGHTINGS NETWORK: WORKING WITH THE PUBLIC 

TO DETERMINE YEAR-ROUND DISTRIBUTION PATTERNS 

Nicola B. Dedeluk 1, Lance G. Barrett-Lennard 1,2, John K.B. Ford 2,3 

1 Vancouver Aquarium Marine Science Centre, P.O. Box 3232, Vancouver, B.C. V6B 3X8 Canada, 

2 Department of Zoology, University of British Columbia, 6270 University Boulevard, Vancouver, 

B.C. V6T 1Z4, 3 Pacific Biological Station, Fisheries and Oceans Canada, Nanaimo, B.C., V9T 6N7 

Canada 

British Columbia’s 800 kilometer coastline is sparsely populated by humans but home 

to at least 17 species of cetaceans. Most of the systematic research on these species has been 

conducted during the summer near Vancouver Island. In an attempt to learn more about the 

relative abundance and year-round distribution of cetaceans in British Columbia, the 

Vancouver Aquarium Marine Science Centre and Fisheries and Oceans Canada established 

the B.C. Cetacean Sightings Network in 2000. In addition to conducting basic research, the 

Network educates the public about conservation issues affecting cetaceans and actively 

promotes the stewardship of marine habitats. Participants file cetacean sightings on a WEB 

form, by e-mail, fax or in special logbooks. All the sightings reports received are entered into 

a comprehensive database. The Network achieves its educational objectives and recruits new 

participants through media interviews, public meetings, paid advertising, and an extensive 

website (www.wildwhales.org). It also co-sponsors a yearly course in marine mammal 

biology, ecology, and conservation for the staff of commercial whale watching companies. 

The website contains information to assist untrained observers with species identification and 

contains an online sighting report form. 

The Network currently has over 200 active participants from most of B.C.’s coastal 

communities. These observers include researchers, vessel operators, commercial and sport 

fishermen, whale watching guides, lighthouse keepers, and other members of the public. To 

date, we have received over 2000 sightings reports, half of which concern killer whales, 

(Orcinus orca). As was expected at the outset most of our sightings are from locations around 

populated areas (Southern and Eastern Vancouver Island) and sixty two percent were filed in 

the summer (Table I). This likely represents a bias in sighting effort, and we are actively 

working to increase effort in the winter and in remote areas. 

Table I: Reported cetacean sightings observation by month from April 2000 to May 2002. 

Jan Feb Mar Apr May Jun July Aug Sep Oct Nov Dec 

# 66 35 120 186 133 306 387 344 271 149 48 58 

% 3.1 1.7 5.7 8.8 6.3 14.5 18.3 16.3 12.8 7.1 2.3 2.8 

Sixty two percent of the 1083 sightings reports of killer whales included information on 

the population (resident, transient, and offshore). Figure 1 shows the breakdown of sightings 

reports by population and month. 



57

250 

200 

150 

100 

50 

0 

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 

Figure 1: Number of reported sightings of identified killer whale populations by month. 

Of f shore 

Transient 

Nort hern Resident 

Sout hern Resident 

Unknown Type 

Southern resident killer whales represent 47% of the sightings received. Northern 

residents accounted for 38% of sightings; transients 15% and offshore killer whales represent 

less than .5%. Like most killer whale studies the B.C. Cetacean Sightings Network is an 

ongoing project. It is only with the long-term gathering of data that we will be able to make 

any predictions about the year-round habitat use by cetaceans on our coast. 



58

VOCAL BEHAVIOUR OF TRANSIENT KILLER WHALES: FOOD CALLING OR 

CONSTRAINED COMMUNICATION 

Volker B. Deecke*†, John K.B. Ford‡† & Peter J.B. Slater* 

*School of Biology, University of St. Andrews, Scotland, UK 

†Vancouver Aquarium Marine Science Centre, Vancouver BC, Canada 

‡Pacific Biological Station, Department of Fisheries and Oceans, Nanaimo BC, Canada 

The cost of vocal behaviour is usually expressed in energetic terms; however, animals may pay 

ecological costs for vocalizing by alerting their predators or prey. The Northeast Pacific is home to two 

distinct ecotypes of killer whales (Orcinus orca): resident killer whales feed on fish, a prey with poor 

hearing abilities whereas transient killer whales hunt marine mammals, which have sensitive underwater 

hearing at the frequencies of killer whale vocal communication. In this study, we investigate whether the 

vocal behaviour of the two ecotypes was shaped by the different hearing abilities of their prey. We 

recorded the vocalizations and associated behavioural context of groups of transient and resident killer 

whales in British Columbia and Southeast Alaska. Transient killer whales emitted pulsed calls 

significantly less frequently than residents. The vocal activity of transients increased after a successful 

attack on a marine mammal, and the levels of vocal activity after an attack were significantly higher than 

for all other behaviour categories except socializing. Since at least some marine mammals respond to the 

calls of transient killer whales, the reduced vocal activity of transients is likely due to a greater ecological 

cost for calling in this ecotype. The fact that transients call after a successful attack could represent food 

calling (informing other animals in the area about the presence of food) or could be due to the fact that the 

ecological cost for vocal behaviour is relatively small after a successful attack. Since the calls after a kill 

are often very faint and since we failed to observe other animals joining a feeding group, a reduced 

constraint on vocal behaviour is the more likely explanation for calling in this behavioural context. 

INTRODUCTION 

The primary function of vocal behaviour in mammals and birds is communication 

between individuals or, in the form of echolocation, orientation and prey detection. Vocal 

behaviour clearly generates benefits but it also has associated costs: in addition to the energy 

required to generate the sound, vocalizing animals may experience costs from passing on 

information to unintended receivers. In the case of predators that specialize on prey with 

sensitive hearing, these costs can be substantial, since the prey is likely to react to the 

predator’s vocalization thus reducing the probability of capture. 

In a variety of animals, vocal behaviour is associated with the discovery or manipulation 

of food. In many cases such vocalizations serve to detect prey (e.g. echolocation) or to 

manipulate prey behaviour. In other cases, however, food-related vocalizations may be 

directed at conspecifics and have communicative function. By attracting conspecifics, such 

food calling may decrease the risk of predation. Alternatively, food calling could attract 

potential mates, or lead to improved access to or defense of a food source. 

The Northeast Pacific is home to two distinct forms of killer whales (Orcinus orca) that 

differ in their behaviour and diet (Ford et al. 1998; Saulitis et al. 2000). The two forms do not 

interbreed and rarely interact. Resident killer whales live in large stable groups and feed 

exclusively on fish, a prey with poor hearing capabilities (Hawkins & Johnstone 1978). 

Transient killer whales live in smaller social groups and prey only on marine mammals with 

acute underwater hearing (e.g. Renouf 1992; Au et al. 2000) that respond to killer whale calls 

(Deecke et al. in press). Barrett-Lennard et al. (1996) showed that transient killer whales use 

echolocation clicks much less frequently than residents. 

In this study, we wanted to investigate the behaviour context in which transient killer 

whales use communicative vocalizations. We wanted to test whether rates of vocal behaviour 



59

are significantly elevated after a successful attack on a marine mammal, and whether transient 

use communicative vocalizations less frequently that the sympatric resident killer whales. 

METHODS 

The data for this study were collected in the summers of 1999-2002 off British 

Columbia and Southeast Alaska. Groups of killer whales were identified photographically and 

followed in a small boat. We stopped the boat ahead of the whales and as they passed we 

recorded underwater vocalizations on DAT tape and measured the distance to the animals 

with laser rangefinders. For each pass, we classified the group’s behaviour as travel, slow 

travel, milling, or socializing using easily quantified variables (swim speed, orientation and 

synchronicity of the surfacing, and the presence of aerial or percussive behaviours). Milling 

after a kill was a separate behaviour category when a marine mammal kill was confirmed. To 

avoid missing faint calls, we only used the sections of recordings when the animals were 

within 500m of the boat. We quantified the level of vocal activity (vocal rate) by dividing the 

number of calls recorded while within 500m of the animals by the amount of time spent 

within this range and the number of animals in the group. 

To identify the behaviour context of vocal activity, we compared vocal rates for the 

different behaviour categories. To test whether vocal activity was related to the presence of 

food (i.e. increased after a successful attack), we compared vocal rates after the kill to the 

vocal rates for all other behaviour categories observed in encounters where a kill could be 

confirmed. Finally, to test for differences in vocal activity between the two killer whale 

ecotypes, we compared vocal rates across all behaviour categories for encounters with 

resident and transient killer whales. 

RESULTS 

The vocal rates showed significant differences between behaviour categories (Kruskall- 

Wallis Test: χ 2 = 16.43, p = 0.002). Vocal behaviour was only common when the animals 

were milling after a kill or socializing. The whales were usually silent (median vocal rate = 0 

calls/individual/minute) during all other behaviours (Fig. 1). Kills of a marine mammal could 

be confirmed in six encounters. In these encounters vocal rates after the kill were higher than 

during all other behaviour categories (Fig. 2) and this difference is significant (Wilcoxon 

Test: Z 6,1 = -2.02, p = 0.043). The comparison of vocal rates during encounters with residents 

and transients (Fig 3) showed that transients use pulsed calls significantly less often that 

resident killer whales (Mann-Whitney test: U = 46, p = 0.029). 

Call rate (calls per individual per min) 

3.5 

3.0 

2.5 

2.0 

1.5 

1.0 

0.5 

0.0 

Resident 

N=8 

Ecotype 

Figure 1: Differences in the rate of pulsed calls by fish-eating (resident) and mammal-eating (transient) killer 

whales across all behaviour categories. 

Transient 

N=24 



60


1.4 

1.2 

1.0 

0.8 

0.6 

0.4 

0.2 

0.0 

After Kill 

N=6 

Behaviour Category 

Other Behaviours 

N=6 

Figure 2: Differences in the rate of pulsed calls when milling after a kill compared to all other behaviour 

categories from the 6 encounters during which confirmed kills were observed 


3.5 

3.0 

2.5 

2.0 

1.5 

1.0 

0.5 

0.0 

After Kill 

N=6 

Socializing 

N=5 

Slow Travel 

N=10 

Travel 

N=15 

Behaviour Category 

Figure 3: Differences in the rate of pulsed calls across behaviour categories. Horizontal bars give median call 

rate, boxes show the interquartile range and whiskers give the range. Horizontal lines delineate homogeneous 

subsets (p < 0.05). 

CONCLUSIONS 

The results of this study show that transient killer whales vocalize only infrequently. 

Transients vocalized most often while milling after a marine mammal kill, and in the 6 

encounters where kills could be confirmed, the levels of vocal activity were significantly 

elevated in this behaviour context. This shows a strong link between vocal activity and the 

presence of food in transient killer whales indicating that vocal behaviour in transient killer 

whales is to a high degree food-associated (in the sense of Janik, 2000). 

In contrast to the findings of Guinet (1992), there is no evidence that the vocal 

behaviour recorded in this study served to attract other killer whales. In no instance were 

other whales observed to join the focal group when it was vocal, although other groups were 

within vocal range on several occasions. In addition, there is no obvious benefit for food 

calling in transient killer whales, and it is therefore unlikely that the animals recorded in this 

Milling 

N=4 



61

study called to signal of the presence of food to conspecifics. The most parsimonious 

explanation for why transients vocalize after a kill is the relatively low cost for vocal 

behaviour after a successful attack. After a kill the animals are satiated, and may not need to 

hunt again for some time, so that alerting potential prey animals in the immediate area does 

not carry a high cost. In addition, the attacks on marine mammals are noisy since they are 

usually accompanied with fast swimming, aerial behaviours and hitting or ramming the prey,. 

Other potential prey animals in the area may therefore already know that killer whales are 

nearby, so that there is no additional cost for vocalizing. 


C. Brignall, N. Dedeluk, D. Matkin, P.-A. Presi, E. Saulitis, G.M. Weingartner, R.M.C. 

Williams, M. Wong, and H. Yurk provided essential help with the field work. In addition, we 

would like to thank L.G. Barrett-Lennard, J.+M. Borrowman, J. DeBoeck, G.M. Ellis, B.+R. 

Lamont, B.+D. MacKay, C. Matkin, D. Matkin, A. Morton, E. Saulitis, J. Watson, and 

R.M.C. Williams for valuable logistic support. Financial and in kind support came from the 

Vancouver Aquarium Marine Science Centre, The BC Wild Killer Whale Adoption Program, 

Glacier Bay National Park, and the BBC Natural History Unit. During part of this study, VBD 

was supported by a DAAD-Doktorandenstipendium aus Mitteln des Dritten 

Hochschulsonderprogramms. 

LITERATURE CITED 

Au, W. W. L., Popper, A. N. & Fay, R. R. (ed.) 2000: Hearing by Whales and Dolphins. 

New York NY: Springer Verlag. 

Barrett-Lennard, L. G., Ford, J. K. B. & Heise, K. A. 1996: The mixed blessing of 

echolocation: Differences in sonar use by fish-eating and mammal-eating killer whales. 

Animal Behaviour 51:553-565. 

Deecke, V. B., Slater, P. J. B. & Ford, J. K. B. in press: Selective habituation shapes 

acoustic predator recognition in harbour seals. Nature . 

Ford, J. K. B., Ellis, G. M., Barrett-Lennard, L.G., Morton, A. B., Palm, R. & Balcomb, 

K. C. 1998: Dietary specialization in two sympatric populations of killer whales (Orcinus 

orca) in coastal British Columbia and adjacent waters. Canadian Journal of Zoology 76:1456- 

1471. 

Guinet, C. 1992: Comportement de chasse des orques (Orcinus orca) autour des îles 

Crozet. Canadian Journal of Zoology 70:1656-1667. 

Hawkins, A. D. & Johnstone, A. D. F. 1978: The hearing of the Atlantic salmon, Salmo 

salar. Journal of Fish Biology 13:655-674. 

Janik, V. M. 2000: Food-related bray calls in wild bottlenose dolphins (Tursiops 

truncatus). Proceedings of the Royal Society of London Series B-Biological Sciences 267:923- 

927. 

Renouf, D. 1992: Sensory reception and processing in Phocidae and Otariidae. In 

Behaviour of Pinnipeds (ed. D. Renouf), pp. 345-394. London: Chapman & Hall. 

Saulitis, E. L., Matkin, C. O., Barrett-Lennard, L.G., Heise, K. A. & Ellis, G. M. 2000: 

Foraging strategies of sympatric killer whale (Orcinus orca) populations in Prince William 

Sound. Marine Mammal Science 16:94-109. 



62

MIRROR IMAGE PROCESSING IN KILLER WHALES (ORCINUS ORCA) 

Delfour F.. 

13 imp. A. Marfaing, 31400 Toulouse, France, fabienne_delfour@yahoo.com. 

The mirror self-recognition paradigm has been used with many species of primates to assess the 

existence of a cognitive ability allowing individuals to understand mirrored information about the self. 

Dolphins and their relatives might be expected to show mirror-induced contingency checking, a 

prerequisite to self-recognition, because of their high brain development, their complex social life and 

their demonstrated abilities in bodily imitation. 

A study of killer whales’ (Orcinus orca) behaviour in front of a mirror is presented here, 

including a mark-test. The results showed the presence of contingency checking behaviours in 

these animals: repetitive/rhythmical head movement, showing tongue (mouth wide opened) 

and shaking head, playing with fish in front of the mirror. Moreover the mark test suggested 

that the mark individual anticipated that its image would look different. 

This study shows that killer whales, like bottlenose dolphins (Tursiops truncatus), appear to 

possess the cognitive abilities required for self-recognition. However we still do not know how an 

individual perceives itself. In order to go further in the investigation it would be valuable not just to 

search for self-recognition per se but also to explore the functions of self-awareness. 



63

SCALING ISSUES IN PREDATOR-PREY INTERACTIONS: KILLER WHALE 

UNDERWATER TAIL-SLAPS 

Domenici, P. 1 , Similä, T. 2 , Batty, R.S. 3 . 

1 CNR, Località Sa Mardini; Torregrande, (Or) Italy, domenici@barolo.icb.ge.cnr.it; 

2 Norwegian Killer Whale Project, Box 181, 8465 Straumsjøen, Norway; 

3 Dunstaffnage Marine Laboratory, PO Box 3, Oban , Scotland. 

Cooperative hunting by killer whales (Orcinus orca) has been reported in a number of 

descriptive studies. However, no previous study has provided a quantitative analysis of the 

kinematics of killer whales’ attacks on fish. Killer whales feeding on herring (Clupea 

harengus) in a fjord in northern Norway were observed using underwater remote-controlled 

video. The whales herded herring into a tight school close to the surface, while periodically 

lunging at it and stunning the herring by slapping them with the underside of their flukes 

while completely submerged. Killer whales then ate the stunned herring one by one. 

Successful tail-slaps occurred in synchrony with a loud noise. This noise was not heard when 

the tail-slaps occasionally “missed” the target, suggesting that the herring were stunned by 

physical contact. The kinematics of tail-slapping were analysed in detail. Tail-slaps consisted 

of a biphasic behaviour , i.e. two phases with opposite angles of attack, a preparatory phase 

and a slap phase. During the slap phase, the maximum angle of attack of the flukes was 47° 

on average. The maximum speed of the flukes was 2.2 Length s -1 (14 m s -1 ) while the 

maximum acceleration of the flukes was size-independent and was 48 m s -2 . The theoretical 

maximum number of herring hit by a tail-slap ranged between 10-47 individual herring. 

Given the high performance of the tail-slaps in terms of speed and acceleration, we suggest 

that tail-slapping by killer whales when feeding on schooling herring is a more efficient 

strategy of prey capture than whole-body attacks, since acceleration and manoeuvrability are 

likely to be poor in such large vertebrates. Scaling issues of vertebrate predator-prey 

interactions involving killer whales will be discussed. 



64

ANALYSIS OF THE DISCRETE CALLS OF KILLER WHALES FROM THE 

AVACHA GULF OF KAMCHATKA, FAR EAST RUSSIA 

Olga A.Filatova(1), Alexander M.Burdin(2), Haruko Sato(3), Erich Hoyt(4), Karina K.Tarasyan(1), 

Alexandra M.Mironova(5) 

Moscow State University, Russia (1); Kamchatka Institute of Ecology and Nature Management 

Petropavlovsk-Kamchatsky, Russia (2); Alaska SeaLife Center, Seward, USA (2); Tokyo, Japan (3); 

WDCS, North Berwick, Scotland (4); Sevvostrybvod, Petropavlovsk-Kamchatsky, Russia (5) 

Acoustic repertoires of killer whales are well studied in several parts of the world. The 

long-term investigations of O. orca acoustic behavior in different parts of the world (Canada 

(Ford 1984, 1991), Alaska (Yurk et al., 2002), Norway (Moore et al., 1988)) provide evidence 

for the existence of a system of vocal dialects unique for each population. But till recently 

Kamchatkian orca population has been unexplored in this way. Our study of acoustic behavior 

of killer whales in Avacha Gulf of Kamchatka at the Russian Far East coast of the North 

Pacific is the first one of this kind in the area. In this study we tried to make a preliminary 

description and classification of discrete call types of the Kamchatkian orcas in order to 

investigate the structure of the acoustic repertoire and to find out whether they have the 

system of pod-specific vocal dialects. 

We obtained and analyzed the sound materials from the three field seasons (September 

1999, 2000, and August-September 2001), from the groups, which were recognized using the 

method of photographic identification. Through these three seasons, we worked for 23 days in 

total and held 39 orca encounters on our surface activities. We have preliminary Photo- 

Identified total of 39 (1999), 86(2000), and 151 individuals in 2001. 

The preliminary classification of calls was made according to the structural features of 

sonograms and my own impressions while hearing them. The following parameters were 

measured from the sonogram: total sound duration; duration of the main component; initial, 

middle and final frequency of the main component; minimum and maximum frequency of the 

main component. The discriminant analysis was made using the program Statistica 5.0. Then 

the results of sound classification were compared with information obtained by 

photoidentification of each group that we met. 

We have found that the acoustic repertoire of Kamchatka O. orca is organized according 

to a hierarchical principle: the majority of sounds can be classified into discrete categories 

with greater or lesser variability in sound structure, allowing us to discern several subtypes. 

We discriminated 27 types and 8 subtypes of discrete calls. In the table 1 you can see the 

distribution of discrete calls recorded from different groups and multi-group aggregations in 

2001. Call repertoires differ from each other, but none of the groups has entirely unique 

repertoire. Hence we suppose that all the groups we met in this area are the members of one 

clan and mate with each other, so we consider them to be the one population. 



65

Date Groups 

KB, 0017a, 0028a, 

q eq eqsh ea eonlybt bwi bd ba clow esv sve chigh svist vizg vlong 13 wv wavc vzw iu i ix in f chavk oa chir kwa 

28.8 0028b, 0028c 

KA6, KB, 0017a, 

+ + + + + + + + + + + 

28.8 0028b, 0028c + + + + + + + + + + + + 

29.8 0129a + + 

31.8 KB, 0129b + + + + + + + 

31.8 KA6, 0128c, 0017a + + + + + + + + + + + + + 

31.8 KA6 

0017a, 0128c, 

31.8 0129b, ?+ 

+ + + 

0017a, 0128c, 

31.8 0129b, ?+ + + + + + 

2.9 KB + + + + + + + + + + + + + + + + + + + 

2.9 KB, 0128c + + + + + + + + + + + + + 

2.9 0129a, 0104b + + 

4.9 0104a, 0104b + + + + + + + + + + + + + 

5.9 0104a, 0105 + 

5.9 0104a, 0106 

5.9 0104a, 0107 

+ + 

6.9 KB, 0128b + 

KB, 9929, 0128b, 

+ + + + + + + + + + + + 

6.9 0129b + + + + + + + + + + + + + + 

6.9 0106 + + + + + + + + 

7.9 KB, 9929a + 

KB, 9929, 9929a, 

+ + + + + + 

11.9 0111 

0017a, ?9929a, 

+ + + + + + + + + + + 

12.9 0128c + + 

12.9 

0017a, ?9929a, 

0128c + + + + + 

Table 1. Distribution of discrete call types recorded in presence of different groups in 2001 

We met supposedly multi-group aggregations on 23 (59%) of our total encounters, so it 

was impossible to determine the repertoire of each pod. We have chosen two groups (KB and 

0106) we met alone for the longest time to describe their repertoires and compare them with 

each other. We discriminated 20 types from the two chosen groups: 18 from the pod KB and 

12 from the pod 0106. Comparison of the repertoires of these groups showed that they shared 

9 call types and 10 types were unique (8 for the pod KB and 2 for the pod 0106)(table2). This 

allows us to predict the existence of a system of vocal dialects for the Kamchatka O. orca 

population. 

KB 0106 

q + 

ea + + 

ex + 

bt + + 

bwi + + 

bd + + 

clow + + 

ce + 

esv + + 

vizg + + 

vlong + 

wvizg + 

wavc + 

i + 

ix + 

f + + 

d + + 

chavk + 

g + + 

unn + 

Table 2. Discrete call repertoires of groups KB and 0106 



66

REFERENCES 

Ford J.K.B. Call traditions and dialects of killer whales (Orcinus orca) in British 

Columbia: University of British Columbia; 1984. 

Ford J.K.B. Vocal traditions among resident killer whales (Orcinus orca) in coastal 

waters of British Columbia. Can.J.Zool. 1991; 69:1454-1483. 

Moore S.E., Francine J.K., Bowles A.E. and Ford J.K.B. 1988. North Athlantic killer 

whales. Journan of the Marine Research Institute, Reykjavik. Vol. XI 

Yurk H., Barrett-Lennard L., Ford J.K.B. and Matkin C.O. 2002. Cultural transmission 

within maternal lineages: vocal clans in resident killer whales in southeastern Alaska. Animal 

behavior 63, 1103-1119 



67

KILLER WHALES (ORCINUS ORCA) IN SHETLAND WATERS 

Fisher P. , Ellis P., Gillham K., Taylor A., Harvey P. 

Shetland Sea Mammal Group, Upper Quoy, Billister, North Nesting, Shetland ZE2 9PR, UK, 

prfisher@lineone.net 

The Shetland Sea Mammal Group is conducting photoidentification work and recording 

sightings of killer whales (Orcinus orca) around the Shetland Islands (60°N, 1-2°W). The aim 

is to study patterns of occurrence of killer whales in coastal waters, their prey preferences, 

hunting strategies and social organisation. The number of reported sightings of killer whales 

has increased markedly in recent years, from less than 20 sightings per year prior to 1993, 

averaging over 50 sightings per year in 1994 - 2000. Pods are seen almost year-round, with 

peaks in sightings in most years during June and July. This may reflect pods returning to 

favoured feeding sites (e.g. seal haul-out sites), or an inshore movement of killer whales from 

different aggregations in the North Atlantic. Observed group sizes range from one to 15 

animals, with a tendency for smaller group size during winter than summer. The killer whales 

appear to live in stable family groups. Marine mammals contribute an important component 

of their diet, with as many as four seals taken during one feeding episode and most land-based 

sightings close to seal haul-outs. There is also one record of a harbour porpoise (Phocoena 

phocoena) taken by killer whales. A juvenile minke whale (Balenoptera acutorostrata) was 

reportedly chased and later stranded in Levenwick Bay in July 1997. Killer whales also feed 

on shoals of mackerel (Scomber scombrus) found inshore, occasionally close to line fishing 

boats. Preliminary acoustic studies suggest that pods are not very vocal whilst transiting along 

the coast in search of marine mammals. Despite concern from environmental groups, no 

studies have been conducted on potential impacts of increased aquaculture activity on marine 

mammals in the area. Whale watching is becoming an important part of local tourism industry 

and killer whales may be seen as a flagship species to promote eco-tourism in the isles. 



68

IS KILLER WHALE (ORCINUS ORCA) BEHAVIOUR DIURNAL? (Poster) 

Foote A. 42 Barfield Avenue, London, N20 0DD, UK, andrew_foote@hotmail.com 

ACOUSTIC RESEARCH PROJECTS FROM THE SEASOUND WORKING 

GROUP, SAN JUAN ISLAND, WASHINGTON, USA. 

Foote, A. Jones , R. Osbourne., V. Veirs., and M. Yoder Williams. 

Contact: a.d.foote@durham.ac.uk 

The Whale Museum, First Street, Friday Harbour, WA, USA. 98250. 

The SeaSound remote sensing network is centred around the installation of remote 

video cameras and a passive underwater acoustic network for sensing the marine environment 

of Haro Strait along the border of British Columbia and Washington State, (fig 1.). 

Fig 1. 

Live video images originate from digital remote cameras at Lime Kiln State Park and 

the Oval Research Station on San Juan Island. The underwater acoustic signals are broadcast 

from an FM radio station (89.1). The primary mission of the SeaSound Remote Sensing 

Network had been to facilitate scientific research, education and stewardship of the whales 

and the ecosystem that supports them through the use of cutting edge technology. 

Independent of the individual collaborative studies described below The Whale 

Museum’s focus over the summer of 2002 has been to maintain its archive of every orca passby 

recorded by the SeaSound systems so that they are available to any interested investigators. 

The other focus of the museum’s efforts this summer has been on improving performance and 

obtaining finer calibration of the remote sensing technology. On the horizon is potential 

funding to collect systematic sound-source measurements on various types of vessels under 

varying conditions using the SeaSound systems. The results of the study would then be 

applied to further developing guidelines for whale watching vessels that minimize noise 

interference to the whales. This summer’s effort to have a truly calibrated system at the 

O.V.A.L. array has been a necessary preliminary step in being able to undertake the accurate 

measurements such a study requires. 



69

PRESENT PROJECTS. 

Val Veirs, Professor of Physics, Colorado College, Colorado Springs, USA. 

I direct the Colorado College OVAL project (Orca Vocalisation and Localisation.) Each 

spring a group of 8-10 Colorado College students come to San Juan Island to study spatial 

relationships between vocalising orcas. We use an array of eight international transducer 

corporation (ITC) hydrophones deployed on fixed underwater stands at the locations shown. 

Time differences are measured and localisations are performed using computer codes written 

by the OVAL team. 

Results of one pass by are shown here. 

On June 25, at 10 p.m., orcas vocalized with calls and echolocation clicks interspersed 

as they passed by southbound. The graphs below show the location and sequence of selected 

echolocation clicks and calls from this pass by. 

E's show the reconstructed locations of echolocation clicks and C's show the locations 

of calls. The colour coding shows the time sequence over the 25 min of this pass by. Notice 

that most of the 83 localized echolocations and calls are in the first half of the pass by (red 

shading to green). The calls come from a region that is about 150m in length and ~40 m wide 

while the echolocation clicks come from a much larger region which includes the calling area. 

Hence the active hunting for fish (echolocation) is being performed over a domain that is 

much larger than the localisations of the interspersed calling whales. 

Andrew Foote, MSc. student, Durham University. 

I am collaborating with The Whale Museum and The Center For Whale Research, 

using data collected over the last several decades to investigate the relationship between 

changes in association patterns over time, pod repertoires and the degree of call sharing 

among Southern Resident pods. I am also assessing possible correlations between call 

function and the degree of within call variability and investigating these data in the context of 

changes in the call's structural parameters over time. Assessment of temporal variation in 

acoustic behaviour over shorter time scales is being undertaken to look for possible 

correlations with foraging behaviour, diurnal activity, and background noise levels. 

Guenevere Jones, PhD. Student, University of Washington. 

I am interested in writing a computer program that can learn to recognize salient 

features in killer whale vocalizations. I will be using the SeaSound hydrophone array to 



70

localize the vocalizations of individual whales. I will then feed the whale vocalizations into 

various computer learning programs (e.g. neural nets, genetic programs) along with the visual 

IDs of the whales to determine if there are features of the vocalizations that are individually 

distinctive. In addition, other information on the whales, such as age, sex, and activity, may be 

fed into the computer program to be correlated with the whale vocalizations. 

Molly Yoder Williams, Undergraduate, Colorado College. 

I am doing a simple analysis of archived recordings from Lime Kiln Lighthouse. My 

study is focused specifically on call trains of a particular call commonly used within the 

Southern Resident community. By examining and comparing a number of basic parameters, I 

hope to better classify and understand one aspect of this species’ acoustic behaviour. I 

addition, correlation will be made with older recordings, to show change over time, and others 

from different locations within the populations range, for locality based comparisons. 



71

REASSESSING THE SOCIAL ORGANIZATION OF RESIDENT KILLER WHALES 

IN BRITISH COLUMBIA 

Ford J.K.B.; Ellis, G.M. 

Pacific Biological Station, Fisheries and Oceans Canada, Nanaimo, BC V9R 5K6 ; 

ford@zoology.ubc.ca 

Killer whales in coastal waters of British Columbia have been studied intensively since 

the early 1970s by means of individual photo-identification. Using data collected during 

1973-87, M.A. Bigg et al. (1990) classified the social organization of fish-feeding ‘resident’ 

whales into five groupings according to 1) the relative strength of bonds of individuals and 

groups from direct observations and co-occurrence in frames of identification photographs, or 

2) similarity in acoustic repertoire. These levels of social organization were defined as 

follows: 

- Matrilineal group: Group of individuals that always travel together and in close 

proximity to one another. The groups are matrifocal. Genealogically, a matrilineal 

group is a matriline of 1 to 4 generations (most 2-3), from which there is no dispersal 

of individuals. 

- Subpod: Closely related matrilineal groups that almost always (>95%) travel with one 

another. Most subpods contain one or two matrilineal groups. 

- Pod: Subpod(s) that travel with one another the majority of the time (> 50%) 

- Clan: An acoustic grouping of pods that share one or more discrete calls, indicating 

that they share a common distant ancestor. Most pods exhibit little preference for 

travelling with other pods within their clan 

- Community: Pods that share a common range and associate with one another. 

Bigg et al. also proposed that new subpods and pods form through a gradual process of 

matrilineal fission, which may take many decades to complete. In expanding populations, 

most pods would be undergoing this process of fission. In populations that are at equilibrium 

or are declining, most social groups would be stable or dying out. 

Our main objective in the current analysis is to examine the fate of matrilineal groups (= 

matrilines), subpods and pods in the northern resident community over an extended study 

period (1973-2000), in order to assess the validity and utility of social organization as defined 

by Bigg et al. 1990. We also attempt to describe the process of fission and fusion in the 

community, and identify possible demographic factors that affect social evolution within 

lineages. Data for this analysis were compiled from a number of sources, and included 

encounters with either photographically or visually identified killer whale groups. 

Association analyses were undertaken at the level of the matriline (= matrilineal group of 

Bigg et al. 1990), which is the basic unit of social structure and has consistent membership. 

Associations of matrilines were determined from their co-occurrence in encounters. 

Matrilines travelling in the same direction and within acoustic range of one another (typically 

< 5 km apart), were considered to be associating. Strength of associations were determined 

from the proportion of encounters in which a pod’s matrilines were together, and with the 

Simple Ratio index of association (calculated with the program Socprog 1.2, provided by H. 

Whitehead, Dalhousie University). 



72

A total of 16 pods were described for the northern resident community by Bigg et al. 

(1990), comprised of 36 matrilines. The community expanded by 60% over the course of the 

study, from 129 animals in 1975 to 208 in 2000. Northern residents were encountered and 

identified on 2979 occasions between 1973-2000. A mean of 4.4 matrilines (± 2.78 SD) were 

present per encounter. Association analyses for the 16 northern resident pods revealed 

considerable fluidity in the bonds among member matrilines across years, and many pods 

underwent fission during the study period, particularly during the late 1980s and 1990s. An 

example is illustrated in the figure below, which shows the proportion of encounters with pod 

A1 in which all three member matrilines were together. Although this pod generally met the 

definition of a pod during the first half of the study period, this was clearly not the case after 

the mid 1980s. 

Proportion of total encounters 

1 

0.75 

0.5 

0.25 

0 

1972 1976 1980 1984 1988 1992 1996 2000 

Proportion of A1 pod encounters with all three matrilines (A12, A30, A36) together, 1973-2000. n = 1912 

encounters 

More dynamic patterns of fission and fusion were seen within other northern resident 

pods. In some pods, member matrilines were together the majority of encounters in certain 

years, and completely apart in others. Preferred associates of numerous matrilines were often 

matrilines from other pods, particularly in recent years. Overall, of the 16 northern resident 

pods described by Bigg et al. 1990, only 8 (50%) still appeared to the meet the definition by 

the year 2000. Of these, 4 pods were composed of single matrilines, which would not be 

expected to undergo fission. All pods that contained two or more matrilines and increased in 

size underwent fission between the mid 1980s and 2000. Demographic factors influencing 

pod splitting may include the death of a matriarch in the matriline, maturation of offspring, 

and the proportion of males in the matriline. 

We conclude that existing definitions of social structure based on group associations are 

neither reliable nor particularly useful because 1) bonds among groups are often dynamic and 

ephemeral, 2) definitions are artificial because they depend on arbitrary measures of bond 

Year 



73

strength and time scales, and 3) bonds are often independent of kinship. An exception to this 

is the community, which includes all matrilines that associate with one another and which 

forms the breeding population. We suggest that definitions of resident society based on 

maternal genealogy are preferable, as such groupings are 1) temporally stable, 2) independent 

of fluctuating group affiliations, and 3) reflect the true population structure. Thus, the most 

useful definitions of social structure within a resident killer whale community are the 

matriline and clan. The term pod should perhaps be used generically to describe any 

aggregation of whales, without implication as to structure, or alternatively as a synonym for 

the matriline. 


This long-term study would not have been possible without the assistance of many 

individuals and organizations over the years. For important contributions to the database of 

northern resident encounters, we thank D. Bain, L. Barrett-Lennard, D. Briggs, J. Borrowman, 

V. Deecke, B. Falconer, C. Guinet, K. Hansen, K. Heise, S. Hutchings, J. Jacobsen, B. 

Mackay, A. Morton, L Nichol, R. Palm, A. Spong, P. Spong, H. Symonds, F. Thomsen, J. 

Watson, E. White, S. Wichniowski, and R. Williams. 

REFERENCE 

Bigg, M.A., P.F. Olesiuk, G.M. Ellis, J.K.B. Ford, and K.C. Balcomb III. 1990. Social organization and 

genealogy of resident killer whales (Orcinus orca) in the coastal waters of British Columbia and Washington 

State. Report of the International Whaling Commission (Special Issue 12): 383-405. 



74

BEHAVIOURAL AND ACOUSTIC DIFFERENCES AMONG BELUGAS 

(DELPHINAPTERUS LEUCAS) SUMMER HERDS IN THE ST. LAWRENCE 

ESTUARY (QUEBEC, CANADA). 

Godefroid A. 1 , Cloutier R. 2 , Michaud R. 3 , Desrosiers G. 1 . 

1 Institut des Sciences de la Mer (ISMER), Rimouski (Québec, Canada ), spiroutonio@hotmail.com; 

2 Université du Québec à Rimouski, Département de biologie, Rimouski (Québec, Canada); 

3 Centre d’Interprétation des Mammifères marins, Tadoussac (Québec, Canada). 

The estuary and gulf of the St. Lawrence river represent the southern limit of the world 

distribution of the belugas. During the summer, belugas are distributed along the St. Lawrence 

estuary whereas, they are wintering in the gulf gathered in large herds. During the summer, 

they gathered in three types of herds : (1) adult, (2) adult and juvenile and (3) mixed. A recent 

photo-identification study has found a strong social segregation between different female’s 

«communities» and male’s «networks», each exhibing strong site fidelity. Our purpose was to 

examine variations in behavioural activity and vocal repertoire of the beluga in different 

sectors frequented by different communities or networks at three specific sites (i.e., Baie- 

Sainte-Marguerite, Cap-Chien, and Isle of Kamouraska). Swimming behavioural activities 

(i.e., directional, multidirectional, and milling) and the vocal repertoire (i.e., 7 types of 

whistles, 3 burst pulsed sounds categories, 2 types of echolocation clics and 3 categories for 

mixed and noisy vocalisations, and jaw claps) have been quantified for each type of herd. 

Behavioural and acoustical (i.e., 32 hours of recordings) data were collected from June to 

September, from land sites, in each one of the sites. Analyses of behavioural data show that 

one type of herd and one swimming behaviour are predominant on each of the three sites (i.e., 

64% of milling at Baie-Sainte-Marguerite with 73,5% of adult herds encountered, 44% of 

directional swimming at Cap-Chien with 44.5% of adult and juvenile herds encountered, and 

41% of multidirectional swimming at Kamouraska with 56% of mixed herds encountered). 

Acoustical data show some differences concerning the proportion of sounds for some 

categories of whistles, clics, burst pulsed sounds and jaw claps that is differing from one site 

to an other. These results will permit a more precise sight on the intra-population organisation 

of St. Lawrence river’s belugas during the summer. 



75

CURRENT KNOWLEDGE OF KILLER WHALES IN THE MEXICAN PACIFIC 

Guerrero-Ruiz M., Urbán-R.J., Gendron D., Flores de Sahagún V. 

Programa de Investigación de Mamíferos Marinos. Departamento de Biología Marina. Universidad 

Autónoma de Baja California Sur. A.P. 19-B. La Paz, B.C.S. 23081. México, megr@uabcs.mx 

Killer whales are widely distributed along the Pacific coast of Mexico, although they are 

only occasionally seen in some areas. Because the population status of killer whales in 

Mexican waters is not clear, the purpose of this report is to present current information on the 

distribution, movements, communities, and feeding habits of killer whales in the Mexican 

Pacific. This long-term study has been based on sighting data and individual photoidentification, 

using the shape and size of the dorsal fin and saddle patch of killer whales. We 

have compiled more than 200 sightings in the Mexican Pacific from published and 

unpublished records from 1858-2002. More than 850 individuals have been sighted with 

group sizes that have ranged from 1-40. More than 90 individuals have been photo-identified 

and more than 30 have been documented more than once. The longest period between reencounters 

of a known individual has been more than 13 years. Based on the individual 

associations, we have suggested four communities of killer whales as temporal inhabitants of 

the Gulf of California. Some individuals belonging to these communities have been moving 

inside and outside the Gulf of California, along the Mexican Pacific, up to California. Killer 

whales in Mexican waters have been seen feeding on baleen whales, dolphins, seals, sea lions, 

sea turtles, sharks, sunfishes, and manta rays. Also, throughout these years, six individual 

strandings and one live mass stranding were recorded as well as a sighting of killer whales 

with remoras. Even though these killer whales have not been linked to any type of killer 

whales they might be similar to the transient type because of their feeding habits, nevertheless 

genetic and acoustic studies are needed to confirm this statement, as well as to determine 

whether or not these animals belong to a different population of killer whales. 



76

ANALYSIS OF PHOTO-IDENTIFICATION DATA TO MAKE INFERENCES 

ABOUT CETACEAN POPULATIONS 

Philip Hammond 

Sea Mammal Research Unit, University of St Andrews, Fife KY16 8LB, UK 

This presentation explores the use of statistical analysis of photo-identification data to 

provide information on abundance, survival, reproduction and movements of cetaceans. The 

examples given relate to humpback whales and bottlenose dolphins, but the methods used and 

the information obtainable are highly relevant to killer whale research in many parts of the 

world. 

ABUNDANCE OF WEST GREENLAND HUMPBACK WHALES 

Most humpback whales in the North Atlantic calve and mate around the West Indies in 

winter and all feed in high latitudes in summer. Although animals from all feeding areas mix 

on the breeding grounds, maternally directed migration leads to high site fidelity of animals to 

particular feeding areas (Gulf of Maine, Eastern Canada, West Greenland, Iceland and 

Norway). The West Greenland feeding aggregation can therefore be considered as a separate 

population. This population has been subject to a traditional subsistence hunt by native 

Greenlanders and to commercial whaling operations in the 1920s. An estimated 800+ animals 

have been taken from the population since 1886. 

To estimate abundance, a photo-identification study was conducted in coastal waters off 

West Greenland in 1988-1993 (Larsen & Hammond, in review); the final two years as part of 

project YoNAH (Smith et al. 1999). During systematic coverage in July and August each year 

670 groups of humpbacks were encountered and a 348 individuals were identified. Animals 

were mostly seen along the inshore edges of banks, particularly along the 200m depth 

contour. 

With these data there are two options for analysis: an open population model, such as 

the Jolly-Seber model applied to all the data simultaneously; or calculating sequential 

estimates for pairs of years using the closed population Petersen model. The latter method was 

adopted for two reasons. First it gives more precise estimates of abundance if the assumptions 

of the method are met, which they were judged to have been (with one exception - see 

following point). Second, it allowed a new method of incorporating matching errors to be 

taken into account (Stevick et al. 2001), which was believed to be important. This method 

utilises data on the false negative error rate in matching as a function of photographic quality. 

A series of analyses were run for each pair of years including increasingly poor 

photographs in the data sets. This was done to find a balance between (a) using only very 

good quality photographs, being certain of not missing matches (no bias), but utilising a small 

proportion of the available data (poor precision) and (b) using all photographs to increase 

precision but risking a bias because of missed matches resulting from poor quality images. 

The Mean Square Error of the estimates (bias 2 + variance) was used to determine the best 

estimates. 

Results showed that all photographs should be included for the best estimate, probably 

because the bias had been largely eliminated by incorporation of the matching error 

correction. The estimates for each pair of years were highly consistent (four were between 

348-376) with one outlier (566 in 1990-91). The outlier had poor precision resulting from a 



77

low number of recaptures and may also have been positively biased due to small sample bias. 

There was no evidence of a trend and average abundance for the period was estimated at 360 

animals with a coefficient of variation of 7%. 

SURVIVAL OF BOTTLENOSE DOLPHINS IN THE SADO ESTUARY 

The Sado Estuary in Portugal is home to a very small resident population of bottlenose 

dolphins (Gaspar et al. in prep). There are other bottlenose dolphins outside the Estuary and 

animals from inside and outside are sometimes seen together, but the Sado animals are 

effectively a separate population. The Sado Estuary is a National Nature Reserve and the 

dolphins have been studied since 1981. Eighty-nine animals have been identified in the 20 

years of study; 29 calves and 60 adults. Residence has been determined by examining 

monthly sighting rates of individuals. The distribution is clearly bimodal with a hiatus 

between animals seen rarely (classified as non-residents) and animals seen frequently 

(residents). 

Almost all individually identified Sado bottlenose dolphins are seen almost every year 

so there is no need to estimate abundance; the data are effectively a census. Numbers of 

resident animals declined from around 40 in the late 1980s to a low of 30 in 1997. This trend, 

combined with a lack of any sub-adult animals maturing into adults prompted concern about 

the viability of the population. Attempts to explain the decline have focussed on using the 

photo-identification data to estimate survival rates (a) for adults, sub-adults and calves, and 

(b) for different periods of time during the study period (Gaspar & Hammond, in prep). 

Data on births were also examined. The number of births and the crude birth rate 

(births/total population size) were lower prior to 1994 than from 1994 onwards. These data 

must be treated with caution, however, because differences in data collection methods mean 

that very young animals are more likely to have been missed in the earlier years of the study. 

Survival models estimate, at minimum, survival probabilities (rates) and capture 

probabilities. These can be time independent (in which case the estimated values are averages 

for the study period) or can be allowed to vary with time. In this analysis, models were 

applied in which both these parameters were time independent or varied over two or three 

periods. For young animals, for which the year of birth was known or could be reliably 

assigned, age-specific survival rates were estimated (1, 2, 3, and 4+ years). Analyses were run 

using program MARK (http://www.cnr.colostate.edu/~gwhite/mark/mark.htm) and Akaike’s 

Information Criterion (AIC) was used for model selection. 

Two models had most support from the data on adult survival. One showed a period of 

high survival during 1986-89 and a period of lower survival 1990-2000. The other showed 

variation over three periods with survival increasing again in 1999-2000. There is thus strong 

evidence for a period of low adult survival at least in the period 1990-1998. 

For young animals, one model had most support from the data. This showed survival 

varying over two periods of time 1984-1993 and 1994-2000. In the early period, first year 

survival was very high which concurs with the likelihood of missed calves in this period. 

Second and third year survival were similar and were combined into a single estimate, which 

was low in the early period and high in the later period. Sub-adult (age 4+) survival was also 

considerably lower in the early than the later period. This latter result concurs with the 

observed lack of recruitment to the adult population. Thus there is strong evidence for a 

period of low calf and sub-adult survival through 1993. 



78

Overall, there is some evidence for low reproduction and strong evidence for low calf 

and sub-adult survival in 1984-1993. This may have triggered the decline in numbers in the 

late 1980s. The decline may then have continued because of low adult survival 1990-1998. 

Reasons for the decline are still unknown. From 1999 onwards, the results show higher 

reproduction and survival rates all round, which may auger well for the future. 

RECENT RANGE EXPANSION OF BOTTLENOSE DOLPHINS OFF 

EASTERN SCOTLAND 

The recent establishment of a Special Area of Conservation (SAC) for bottlenose 

dolphins in the Moray Frith (NE Scotland) has focussed attention on this small, resident, high 

latitude population. Relevant to how well the SAC will provide protection for the population 

is a suspected range expansion indicated by an increase in incidental sightings of dolphins in 

the outer Moray Firth and then south to St Andrews Bay during the late 1990s. Because this 

could be indicative of the discovery of an existing range driven by an increased awareness and 

interest following the establishment of the SAC, rather than a true range expansion, photoidentification 

data were used to investigate this systematically (Wilson et al., in review). A 

subset of 54 well-marked animals that were alive in 1990-92 and still alive in 1998-2000 was 

used in analysis. Animals were divided into three groups: (a) inner Moray Firth only; (b) inner 

+ outer Moray Firth; (c) inner + outer Moray Firth + south to St Andrews Bay. 

Previous work had shown a clear spatial structuring of the population with animals seen 

most frequently also seen closer to the head of the inner Moray Firth (Inverness), with this 

pattern being maintained seasonally (Wilson et al. 1997). This pattern has been conserved 

with the inner Moray Firth only animals seen closer to Inverness and more frequently than the 

others. Both these difference are highly significant. So there is clear evidence of a spatially 

structured population with some individuals consistently staying close to the head of the inner 

Moray Firth and others consistently spending less time there. If the range had truly expanded, 

we would expect to see the “outer Moray Firth” animals (groups b and c) less and less 

frequently through the 1990s because these are the animals that would be moving further and 

further afield over time. This pattern was indeed observed. 

A second, less obvious, line of evidence involves investigating the cause of death and 

distribution of stranded harbour porpoises. Bottlenose dolphins attack and kill harbour 

porpoises (Ross & Wilson, 1996) and animals that die in this way can be identified in post 

mortem examinations through characteristic signs (multiple fractures, ruptured internal 

organs, distinctive cuts and bruises). We compared the distribution of stranded porpoises 

dying as a result of violent interactions with bottlenose dolphins with the distribution of those 

dying from other causes (a total of >200 strandings). In 1990-95, “other causes” strandings 

were distributed all down the coast to St Andrews Bay (and beyond). This pattern was the 

same in 1996-2000. There was no difference in the median distance of strandings from 

Inverness. “Violent interactions with bottlenose dolphin” strandings were distributed similarly 

in 1996-2000 but in the period 1990-1995 very few were seen south to St Andrews Bay. And 

there was a significant difference in the median distance from Inverness. This implies that 

there were few bottlenose dolphins in the southern part of the area in the early 1990s. 

In summary, there is clear evidence for range expansion. All animals seen outside the 

inner Moray Firth were also seen in the inner Moray Firth so all animals belong to the same 

population. Outer Moray Firth animals are still being seen in the inner Moray Firth so this is a 

range expansion, not a range shift. And the spatial stratification in distribution in the inner 

Moray Firth has been conserved through the 1990s; the dolphins seen farthest from Inverness 



79

are the outer Moray Firth animals. For the strandings, the distribution of porpoises that died as 

result of violent interactions with bottlenose dolphins has extended south during the 1990s. 

The observed range expansion is most likely related to food availability. If prey had 

declined in the inner Moray Firth, animals may have been forced to range more widely to find 

food, or new prey resources may have been discovered by wide ranging individuals, or both. 

The spatial stratification is interesting in this context. If some animals now spend more time 

outside the inner Moray Firth, why do some animals stay all the time in the inner Moray 

Firth? Is this because of partitioning of prey resources, or competition for resources? 

REFERENCES 

Gaspar, R., Silva, A., Harzen, S. & dos Santos, M.E. (in prep). Long-term photoidentification 

study of bottlenose dolphins in the Sado Estuary: residency, population size and 

reproductive parameters. 

Gaspar, R. & Hammond, P.S. (in prep). Changes in survival and other population 

parameters in a very small bottlenose dolphin population. 

Larsen, F. & Hammond, P.S. (in review). Distribution and abundance of West 

Greenland humpback whales. Canadian Journal of Zoology. 

Ross, H.M. and Wilson, B. (1996). Violent interactions between bottlenose dolphins 

and harbour porpoises. Proceedings of the Royal Society, London, B. 263: 283-286. 

Smith, T.D., Allen, J., Clapham, P.J., Hammond, P.S., Katona, S.K., Larsen, F., Lien, J., 

Mattila, D.K., Sigurjónsson, J., Stevick, P., Øien, N. (1999). A ocean-basin-wide markrecapture 

study of the North Atlantic humpback whale (Megaptera novaeangliae). Marine 

Mammal Science 15: 1-32. 

Stevick, P.T., Palsbøll, P., Smith, T.D., Bravington, M.V. & Hammond, P.S. (2001). 

Errors in identification using natural markings: rates, sources and effects on capture-recapture 

estimates of abundance. Canadian Journal of Fisheries and Aquatic Sciences 58: 1861-1870. 

Wilson, B., Thompson, P.M. & Hammond, P.S. (1997). Habitat use by bottlenose 

dolphins: seasonal distribution and stratified movement patterns in the Moray Firth, Scotland. 

Journal of Applied Ecology 34: 1365-1374. 

Wilson, B., Hammond, P.S., Reid, R.J., Grellier, K. & Thompson, P.M. (in review). 

Recent range expansion in North Sea bottlenose dolphins: evidence and management 

implications. Conservation Biology. 



80

ASSESSING THE IMPACTS OF KILLER WHALE PREDATION ON STELLER SEA 

LIONS IN WESTERN ALASKA 

Heise, K. 1 , Barrett-Lennard, L.G. 1,2 , Martell, S. 3 , Saulitis, E. 4 , Matkin, C. 4 , DeMaster, D. 5 , Trites, A. 6 

1 Dept. of Zoology, University of British Columbia, 6270 University Blvd., Vancouver, BC., V6T 

1K8; : heise@zoology.ubc.ca 

2 Vancouver Aquarium Marine Science Centre, Box 3232., Vancouver, B.C. V6B 3X8; 

3 Fisheries Centre, 6248 Biological Sciences Road., Vancouver, V6T 1Z4; 

4 North Gulf Oceanic Society, 60920 Mary Allen Ave., Homer, AK 99603; 

5 National Marine Mammal Laboratory, Alaska Fisheries Science Centre, 7600 Sand Point Way NE, 

Seattle WA 98115; 

6 Marine Mammal Research Consortium, Fisheries Centre, 6248 Biological Sciences Road, Vancouver, 

BC V6T 1Z4. 

The western Alaskan population of Steller sea lion (Eumetopias jubatus) has declined 

dramatically from approximately 264,000 in the late 1970's to as few as 35,000 to 42,000 

animals in 2000. The discovery of flipper tags from 14 Steller sea lions in the stomach of a 

dead killer whale (Orcinus orca) in 1992 focused attention on the possible role that killer 

whale predation may have played in this 85% decline. We compiled killer whale stomach 

content information and surveyed mariners in order to better understand the evidence for 

killer whale predation on Steller sea lions. We then used simulation models to test the 

hypothesis that killer whale predation could have caused the decline. 

We began by reporting the results of stomach content analyses of 8 transient/ transient 

like killer whales from Alaska. One stomach was empty, and only 2 contained Steller sea lion 

remains. Harbour seals appeared to be the predominant prey, and were found in all 7 

stomachs containing remains (one was empty). Two stomachs contained Dall’s porpoise, 1 

contained beluga, 1 contained river otter and 1 contained bird feathers. We also surveyed 

mariners to determine the frequency and outcome of observed attacks on sea lions, the age 

classes of sea lions taken, and the areas where predatory attacks occurred. We received 126 

responses to our survey from mariners from Alaska and British Columbia. They described 

492 interactions between killer whales and sea lions, of which 32 were predatory attacks. 

Most of the described attacks were of adult sea lions, however repeated visits by transient 

killer whales to rookeries and haulouts suggest that pups and juveniles may be attacked and 

consumed underwater. 

We used this information, along with Steller sea lion life history data, to build stochastic 

age-structured predation models designed to test the hypothesis that the decline was driven by 

killer whale predation. We then generated likelihood profiles to estimate the number of 

transient killer whales and the proportion of Steller sea lions in their diet that would have been 

sufficient to cause the decline. Our results indicate that a population of 250 transient killer 

whales could account for the observed decline of sea lions in western Alaska if a dietary shift 

occurred in the early 1970’s such that an additional 28% of their caloric intake was provided 

by sea lions (Figure 1). The model further indicates that as few as 120 transients, with 20% 

more of their diet supplied by sea lions than prior to the decline, could effectively trap the 

present population of western Alaskan sea lions in a predator pit (Walters 1986) and prevent it 

from recovering. 



81

It is plausible that earlier declines of alternative prey (e.g. northern fur seals and harbor 

seals) led killer whales to shift a greater proportion of their diet to Steller sea lions in the 

1970’s. Our models indicate that a substantial impact of killer whale predation on the western 

Steller sea lion populations cannot be ruled out with available data. We therefore recommend 

that future field studies should focus on determining the number of transient killer whales in 

western Alaska and the proportion of Steller sea lions in their diet. We also think it is 

important to investigate the impact of killer whale predation on other species such as harbour 

seals, fur seals and porpoises in western Alaska, and on sea lion stocks in other areas. 

Figure 1. Likelihood profile for the proportion of Steller sea lions in the diet of 125 and 

250 transient killer whales. Likelihoods were rescaled to values between 0 and 1. If the 

proportion of sea lions in the diet of 250 killer whales increased 0.28 (CI 0.26-0.3) beginning 

in 1974, this would be sufficient to cause the decline. The decline can also be explained if the 

proportion of sea lions in the diet of 125 killer whales increased 0.56 (CI 0.52-0.6). 

Acknowledgements: We thank Eva Saulitis for her involvement in this project in its early 

stages, and Arliss Winship for his help in completing the figures. We also thank the many 

mariners who replied to our survey. We are very grateful to David Bain, Rich Ferrero, Donna 

Willoya, Kate Wynne, and Liana Jack for contributing stomach content information. We also 

thank the late Bud Fay, Elaine Humphries, William A. Walker and Pacific Identifications 

(Victoria BC) for identifying stomach contents, and Graeme Ellis for photo-identifying killer 

whales. We are also very grateful for funding provided from the North Gulf Oceanic Society, 

and to NOAA and the North Pacific Marine Science Foundation for grants to the North 

Pacific Universities Marine Mammal Research Consortium. 



82

WORLD-WIDE GENETIC DIVERSITY IN THE KILLER WHALE (ORCINUS 

ORCA); IMPLICATIONS FOR DEMOGRAPHIC HISTORY. 

Hoelzel R.A. 1 , Natoli A. 1 , Dahlheim M.E. 2 , Olavarria C. 3 , Baird R.W. 4 , Nicholson C. 1 , Black N.A. 5 . 

1 Department of Biological Sciences, Durham University, South Road, Durham, DH1 3LE, England, 

a.r.hoelzel@dur.ac.uk; 

2 National Marine Mammal Lab., NMFS, 7600 Sand Point Way N.E., Seattle, WA, 98115, USA; 

3 School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland, New 

Zealand; 

4 Biology Department, Dalhousie University, Halifax, Nova Scotia, B3H 4J1, Canada; 

5 Monterey Bay Cetacean Project, P.O. Box 52001, Pacific Grove, CA 93950, USA. 

A low level of genetic variation in mammalian populations where the census population 

size is relatively large has been attributed to various factors, such as a naturally small 

effective population size, historical bottlenecks, and social behaviour. The killer whale is an 

abundant, highly social species with reduced genetic variation. We investigated both mtDNA 

(sequence data for up to 1,820bp) and microsatellite DNA loci among samples from the 

eastern North Pacific, western South Pacific, western North Atlantic, eastern North Atlantic, 

western South Atlantic, and Antarctic and found no consistent geographic pattern of global 

diversity, and no mtDNA variation within some regional populations. For example, the 

overall level of nucleotide diversity for the mtDNA control region was π = 0.005, a level 

comparable to that commonly seen for species known to have undergone a population 

bottleneck. Genetic distance was in some cases greater between populations in sympatry than 

between populations in separate oceans. The regional lack of mtDNA variation is likely to be 

due to the strict matrilineal expansion of local populations, a consequence of their matrifocal 

social behaviour. Related mechanisms could in turn lead to reduced mtDNA variation worldwide, 

however the pattern of variation among putative populations and among haplotypes 

suggests the possibility of an historical population bottleneck as an additional factor. 



83

SOCIOECOLOGY OF KILLER WHALES (ORCINUS ORCA) IN NORTHERN 

PATAGONIA 

Iñíguez M.A., Tossenberger V.P., Gasparrou C. 

Fundación Cethus. Juan de Garay 2861 Dto “3”, Olivos, (1636), Pcia de Buenos Aires, Argentina, 

tovera@sanjulian.com.ar 

Observations on killer whales in Northern Patagonia were done using photoidentification 

techniques between 1985 and 1999. Thirty killer whales have been identified in 

the study area since 1975 but a core group of 17 have been found to return to the area each 

year. Boat and shore observations were conducted during both the austral summer-autumn 

season 1985-1999 and the austral winter season 1992-1993, using the individual follow 

protocol. The objective of this paper is to study the long-term association and composition of 

killer whales pods in Northern Patagonia, Argentina. The 17 individuals regularly seen in the 

region were classified at the beginning of the field programme into three pods PNA, B and C. 

The pods contain 6,2 and 9 killer whales respectively. Group size ranged from 1 to 10. 

Between 1991 and 1993, A1, A2, A4, A6, B1 and C2 were no longer sighted. After 1993, 

changes in the pod composition were observed. First, association between A and B pods was 

observed and since 1994 between A and C pods. B pod interacted with all the other pods. 

Dispersal of both sexes from groups larger than three individuals was observed and it may be 

related to foraging strategies and provisioning. Individuals from different pods abandoned 

their maternal groups to made up new aggregations. 



84

COOPERATIVE HUNTING AND PREY HANDLING OF KILLER WHALES IN 

PUNTA NORTE, PATAGONIA, ARGENTINA 

Iñíguez M.A., Tossenberger V.P., Gasparrou C. 

Fundación Cethus. Juan de Garay 2861 Dto “3”, Olivos, (1636), Pcia de Buenos Aires, Argentina, 

tovera@sanjulian.com.ar 

Field observations carried out between 1989 and 1999 were used to describe the prey 

species and feeding behaviour of killer whales in Northern Patagonia. They fed almost 

exclusively upon pinnipeds including southern sea lions (Otaria flavescens) and southern 

elephant seals (Mirounga leonina). Southern sea lions comprised 85.71% and of them, 

82.25% were pups. Killer whale diet in Northern Patagonia also included southern elephant 

seals (3.89%), magellanic penguins (Spheniscus magellanicus) (3.89%) and fish (6.06%). A 

record of a silvery grebe (Podiceps occipitalis) killed by killer whales was also reported. 

Killer whales used mainly intentional stranding techniques to hunt pinnipeds (n=174). 

Intentional stranding events were timed, and each one was found to last between 8 and 81 

seconds ( X =29.22 sec). The feeding behaviour that followed the stranding events lasted from 

1 to 82 minutes ( X =18.00´). A1, A3, A5, B1, B2, C1, C4, C5 individuals killer whales were 

involved in hunting events as hunters. Seven different hunting techniques were observed 

including intentional stranding, pursuit, circling, strike with the fluke, close approach, breach 

and semi-intentional stranding. Intergroup conflicts over prey patches or prey carcasses were 

observed. Prey sharing was registered on 109 occasions. Foraging association between all 

three pods (A, B and C) were observed on 29 occasions. Eleven teaching events, where calves 

were tutored on hunting techniques were identified. 



85

KILLER WHALE (ORCINUS ORCA) SIGHTINGS IN ALASKA: PRELIMINARY 

RESULTS FROM MARINER SURVEY DATA 

Kerry E. Irish 1 , John K.B. Ford 2,4 , Lance G. Barrett-Lennard 3,4 and Andrew W. Trites 1 

(1) Marine Mammal Research Unit, University of British Columbia, Room 18 Hut B-3 6248 

Biological Sciences Road, Vancouver, B.C. CANADA V6T 1Z4 

(2) Pacific Biological Station, Department of Fisheries and Oceans, Nanaimo, B.C. CANADA V9R 

5K6 

(3) Vancouver Aquarium Marine Science Centre, P.O. Box 3232, Vancouver, B.C. CANADA V6B 

3X8 

(4) Department of Zoology, University of British Columbia, 6270 University Boulevard Vancouver, 

B.C. CANADA V6T 1Z4 

Long term, systematic studies of the natural histories and population status of resident 

and transient killer whale populations have been conducted in the coastal waters of the 

northeastern Pacific from Washington State to the Kenai Fjords. These studies have provided 

reliable population estimates and a good understanding of life history and ecology for killer 

whales in these regions. Such comprehensive studies have not yet been undertaken in the 

northern Pacific west of the Kenai Fjords, although initial field efforts are currently underway. 

There is thus a paucity of data on the abundance, distribution, population structure and 

foraging behaviour of killer whales in this region. 

Although killer whales have a cosmopolitan distribution throughout the world’s oceans, 

they are far more abundant in some regions than others. This makes initial investigations of 

killer whale biology in new areas challenging, as few parameters exist to focus field efforts 

and many of these areas are remote and difficult to survey. While line transect protocols are 

an effective method for assessing the density and distribution of some odontocete species, this 

approach has not proven useful for killer whales. Previous efforts to use line transect surveys 

have been difficult because of the non-random distribution of killer whales - due to the 

existence of distributional “hot spots”, and furthermore these hotspots are ephemeral on both 

annual and multi-annual time scales. Thus a key element in many killer whale studies around 

the globe is the role of the lay observer in reducing the time researchers spend looking for 

whales. The prominence of killer whale mythology in the local culture, the relatively low 

probability of species misidentification and the high levels of motivation and enthusiasm 

combine to make Alaska an ideal area in which to employ lay observers. In addition, the 

logistical and fiscal constraints of embarking upon dedicated surveys indicate that there may 

be considerable advantage in using an alternative means of collecting baseline information on 

killer whales of this region. 

The late Michael Bigg surveyed local mariners in British Columbia over a weekend for 

three successive summers in the early 1970’s to investigate killer whale distribution. By 

engaging mariners who were already on the water to look for killer whales allowed him to 

quickly and economically establish a ‘snapshot’ of killer whale distribution by increasing the 

survey area coverage. This method provided a minimum estimate of killer whale abundance 

for British Columbia that was later confirmed by photo-identification studies as relatively 

accurate. Bigg also found that while widely distributed, there were key "hot spots" where 

killer whales would aggregate. Mariner survey data from western Alaska should also help to 

locate such “hot spots”, which may be useful for guiding future research efforts in this region. 



86

Using this method established by Bigg, killer whale sighting forms were disseminated 

widely to mariners throughout Alaska via print and audio media, a dedicated web site 

(www.AlaskaKillerWhales.org), a notice to mariners, local contacts and commercial interests. 

Alaskan mariners were asked to look for killer whales during the weekend of July 19 – 21, 

2002 and fill in a survey form whether they saw killer whales or not. On the survey form, they 

were asked three sets of questions; to describe the route taken and general weather conditions; 

if killer whales were seen or not; and general information about previous encounters with 

killer whales. One hundred-sixty survey forms were collected during that weekend from 

mariners throughout Alaska. Participation was fairly evenly distributed with 38.8% of the 

surveys collected from south-central Alaska, 34.1% from the Aleutians and 27.1% from 

southeastern Alaska. 

The largest number of surveys were submitted by recreational mariners (32.3%), 

followed by commercial fishermen (27.7%) and charter operators (26.2%). Other notable 

contributors included Alaska State Ferries, US Coast Guard, and various government and 

independent researchers. The majority of participants mailed in their surveys (39%), with a 

notable number using the web interface (28%) or facsimile (25%), and a few emailed (6.25%) 

or phoned (1.6%) in their survey results. 

Forty of the surveys reported sightings of killer whales. The greatest number of those 

sightings came from Southeast Alaska (46.5%), the second greatest number of sightings came 

from South Central Alaska (37.2%) with the fewest number of sightings reported from the 

Aleutians (16.3%). The majority of sightings reported group sizes of 1– 8 individuals with a 

mean of 4 (80%) ten percent reported group sizes of 11-15 and 10% reported groups sizes of 

30-40. 

Initial spatial analysis (uncorrected for effort) shows three potential hot spots of killer 

whale sightings; Unimak Pass (Aleutians); Prince William Sound (South Central Alaska) and 

near Juneau (Southeast Alaska). Additional analysis will consider survey effort, bathymetric, 

fisheries catches and marine mammal distributions with both killer whale sightings and areas 

surveyed. A comparison of these data with those collected by Bigg in the 1970’s British 

Columbia surveys will be undertaken as well. The next survey is planned for the first week of 

March 2003, in an effort to increase sample size and look for potential differences in seasonal 

distribution. 



87

BIOENERGETIC CHANGES FROM 1986 TO 2002 IN SOUTHERN RESIDENT 

KILLER WHALES, ORCINUS ORCA 

Kriete B. 

53 Orca Relief, Limestone Point Road, Friday Harbor, WA, 98250, USA Kriete, birgit@orcarelief.org 

From 1996 to 2001 the population of the southern resident population of killer whales 

(Orcinus orca) in northern Puget Sound, WA, USA, decreased from a high of 98 individuals 

to a low of 79 animals, a reduction of almost 20% in only 6 years (Bain 2002). At the same 

time, whale watching ecotourism in the area increased from 2 commercial whale watch 

operations in 1987 to over 90 commercial boats in 2000 (Bain 2002). This study provides a 

comparison of the physiological changes of the southern resident killer whale population from 

a period of very little boat traffic to an era of increased marine vessel commerce. 

Data on energy expenditure and daily caloric requirements were measured in the 

southern resident killer whale population in the mid-1980’s (Kriete 1995). Swimming 

velocities and respiration rates in different age/sex classes of traveling wild killer whales were 

collected in all research seasons. These data were combined with oxygen consumption 

measured during different activities of captive orcas to determine bioenergetic requirements 

for killer whales. 

The same study on wild killer whales was repeated in 2001 in the same location. 

Swimming speeds and breathing rates showed statistically significant increases over those of 

the mid-1980’s. Adult killer whales expended close to 20% more energy due to increased 

swimming velocity in 2001 compared to the 1980’s. Increases in metabolic rates must be 

balanced by an increase in food consumption and additional feeding behavior was observed in 

2001. While environmental conditions were very similar between the observation eras, the 

only change was the exorbitant increase in both commercial and private boats following the 

whales for more than 14 hours per day. We believe, therefore, that there is a direct 

relationship between the increase in metabolic rates in southern resident killer whales and the 

increase in whale watch operations. 



88

SURFACE INTERVALS OF AN ADULT MALE KILLER WHALE IN NORWAY 

Leyssen, T. (1), Similä, T. (2), Hanson M. Bradley (3), Holst, J.C. (4), Øien, N.(5) 

(1) NORCA, Rozenlaan 8 3650 Dilsen-Stokkem, Belgium. 

(2,4,5) Institute of Marine Research, P.O.Box 1870 Nordnes, 5817 Bergen, Norway 

(3) NOAA, Alaska Fisheries Science Center, National Marine Mammal Laboratory, 7600 Sand Point 

Way NE, Seattle, WA 98115 USA 

Surface intervals are frequently used in cetacean studies to describe surface activity and 

energy consumption. During fall 2000 surface intervals of killer whales in northern Norway 

were studied visually by keeping track of a recognizable individual during different 

behaviours (1). Because these whales only enter the fjords during early winter, weather and 

light conditions limited these observations to few hours per individual. 

In December 2001 an adult male killer whale was equipped with a satellite tag. Before 

release a suction cup TDR (Time-Depth recorder, Wildlife Computers) was also deployed 

which recorded depth and swimming speed for 60 hours. The TDR stayed on for longer than 

any TDR deployed on killer whales before. The reason for this must be because the whale was 

restrained during the tagging and the tag could be attached with care and in a good location. 

The collected data set contained 4885 surfacings. The data was analysed for possible 

diurnal changes in the surfacing pattern and also for possible differences between the TDR 

data and earlier data on adult males collected as visual observations. 

BOUTS 

Whales’ surface intervals typically occur as bouts. To distinguish between the withinbout 

surface intervals and the inbetween-bouts surface intervals, we need to calculate the bout 

criterion interval (BCI) 

The Log-Survival function shows that the distinction between short (within bouts) and 

long (in between bouts) dives, has a cut-off point (BCI) at 44 seconds 

This agrees well with the previous study (1), where this was put at 41 seconds. 

SURFACE INTERVALS 

To compare the surface intervals with visually acquired data from previous studies, the 

surface intervals in this study were grouped per 10 minutes. 

An overview of the results from the previous study (1) 

median surface No of blows mean duration of 

interval (sec) per 10 min long dives (sec) 

subsurface feeding 13,1 27,3 72,9 

travel feeding 26,7 17,6 157,5 

travel / foraging 22,2 11,9 138,5 

resting 18,8 11,3 180,9 

The median surface intervals, as calculated per 10 minutes, have a mean of 26.6 

seconds, with a minimum of 14 seconds and a maximum of 186 seconds. This maximum 

value far exceeds anything recorded during visual observations. However, 349 of the 363 

median values were smaller than 44 seconds. 359 values smaller than 80 seconds. 



89

Some of the exhalation intervals were longer than 2 minutes, with as little as 2 

surfacings in 10 minutes. This kind of surface intervals were not recorded through visual 

observations. This is to be expected. With visual observations it is very important not to miss 

any surfacings. With very long surface intervals, the whale might move a long way between 

the surfacings, and therefore you can’t be sure you missed none. As a consequence, the 

datasets with such long surface intervals will mostly be discarded. This explains the 

discrepancy in maximum value for median surface intervals. 

nr of 10 min periods 

60 

50 

40 

30 

20 

10 

0 

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 

number of surfaces per 10 min 

In this study: the mean number of blows is 13.4 per 10 minutes, with a minimum of 2 

and a maximum of 22. If we compare these numbers with the table above, we see that this 

corresponds with travel and resting behaviour. Non of this data corresponds with subsurface 

feeding. 

seconds 

Number of intervals 

200 

150 

100 

50 

0 

400 

300 

200 

100 

0 

1 

12 

18 

14 

35 

16 

52 

18 

69 

Mean Surface Intervals per 10 minutes 

86 

20 

103 

120 

137 

154 

171 

188 

205 

10 minute periods 

222 

Within-bouts surface intervals 

22 

24 

26 

28 

30 

seconds 

32 

239 

256 

273 

290 

307 

324 

341 


34 

36 

38 

40 


42 

44 

358 

All surface 

intervals 

mean = 44.6 sec 

median = 23 sec 

mode = 19 sec 

maximum = 392 sec 

minimum = 6 sec 

Within-bout 

surface intervals: 

mean = 22.8 

seconds 

median = 21.5 

seconds 

mode = 21 seconds 

90

VARIABILITIES IN SURFACE INTERVALS OVER TIME 

There were large changes in the surfacing pattern throughout the 60 hour period, but no 

diurnal pattern could be observed. Sixty hours of recording is substantial data collected with a 

TDR but it is a limited time span in a whales’ life. However if there was a rigorous diurnal 

rhythm, it would have shown in 60 hours. 

The mean surface intervals per 10 minute period was 48.4 seconds, with a standard 

deviation of 18.7 seconds, a minimum of 24.2 seconds and a maximum of 175.7seconds. 

As can be seen from the graph on the left, there were 2 stretches of longer dives (period 

60 to 120, or about 10 hours). 

If we exclude these 10 hours, we have about 50 hours where the mean surface intervals 

per 10 minute period was 41.9 seconds, with a standard deviation of 9.7 seconds, a minimum 

of 24.2 seconds and a maximum of 67.8 seconds. These 10 hours have a mean surface interval 

per 10 minute period of 72.1 seconds, with a standard deviation of 42.1 seconds. This shows 

not only that during this period of 10 hours the diving was prolonged but also much more 

variable. 

THE EFFECTS OF TAGGING. 

This whale was caught and held for about an hour in order to attach a satellite and radio 

tag. Then the suction cup TDR was attached and the whale was released. 

As in any tagging, it is important to consider the effects of the tagging on the behaviour 

of the animal. There are 2 possible effects: 

1. The effect of moving around with the tags attached to the body, which will cause 

extra drag (was kept to a minimum by shaping the tags).and might cause annoyance This 

effect is very difficult to quantify as we don’t have any information about swimming speed 

and diving depth of a non-tagged whale. However, the fact that the results of this study 

correspond well with earlier visual data, lets us assume that this effect will not be very large. 

2. The effect of the tagging process. Here we can look at the surface intervals, dive 

depth and swimming speed after release and compare this data with a period sufficiently later. 

After release the whale made deep dives with long surface intervals for 10 minutes. After this 

there is no discernable effect on surface intervals and dive depth. The swimming speed stayed 

relatively high for 1 hour. It is impossible to know how much of this is caused by the tagging, 

but after 1 hour the data becomes indistinguishable from the rest of the recording period. It 

would therefore be safe for us to assume that this effect lasts for maximum 1 hour. There are 

more occurrences of fast swimming later on in the dataset. Compared to those, this first period 

of fast swimming is characterised by lower maximum swimming speed but more sustained 

speed. To err on the safe site, we excluded the first 2 hours of data from the analysis. 

CONCLUSION: 

The study shows that visual observations are a reliable way of observing surfacing 

patterns of individual killer whales, but a TDR is more reliable than visual observations in 

studying long surfacing intervals. 

There was no diurnal pattern to the surface intervals of this whale during the 60 hour 

recording period. 

In our study area, discerning potential diurnal or other patterns in surfacing behaviour is 

not possible through visual observations. and therefore the use of a TDR gave us a new 

insight into this behaviour 

(1) Turunen, Sanna. 2001. The feeding behaviour of killer whales (Orcinus orca) in the wintering grounds of Norwegian springspawning 

herring. BSc thesis, University of Aberdeen. 



91

PREDATORY ACTIVITY OF A SINGLE KILLER WHALE, ORCINUS ORCA, AT A 

STELLER SEA LION, EUMETOPIAS JUBATUS, ROOKERY IN ALASKA 

Daniela Maldini, John Maniscalco, Alexander Burdin 

Alaska SeaLife Center, PO Box 1329, Seward, AK 99664 

Eastern North Pacific Steller sea lions of the Western stock have dramatically 

declined. These estimates prompted their listing as Endangered in the Western stock in 1997. 

To determine the reasons for such decline, the US Federal government has recently 

committed considerable funding to the scientific community. 

One of the possible factors being explored by scientists to explain the decline is 

the importance of predation by other marine mammals. The effects of predation pressure have 

been so far investigated with conflicting results. Part of the problem has been the scarcity of 

data available on both the rate of predation and on the number of predators exacting pressure 

on Steller sea lions. 

Apart from man, there are only two types of predators thought to take Steller sea 

lions: Pacific sleeper sharks and killer whales of the transient type, and the predation by 

sharks has only been postulated based on few stomach contents since an attack has never been 

witnessed. This leaves killer whales as the most likely candidate for a predator-prey theory. 

The Alaska SeaLife Center (ASLC), in cooperation with the North Gulf Oceanic 

Society (NGOS), is operating in the area of the Prince-William Sound/Kenai Fjords, in 

Southcentral Alaska where some of the largest declines in Steller Sea Lions have occurred. 

The ASLC is concentrating on the area around Chiswell Island, a well monitored SSL rookery 

where pupping occurs. 

Transient killer whales are known to visit SSL rookeries to forage. They travel in 

small pods (1-7 individuals) over large areas, hunting on various kinds of marine mammals 

and birds. Based on long-range studies on the life history of transient killer whales around the 

world, particular pods appear to specialize in a specific type of marine mammal (some are 

seal specialists, others sea lion specialists, etc). This specialization is not exclusive of other 

prey types if the main prey is not available, but does appear to dictate the particular hunting 

strategies of a pod. 

In the Kenai Fjords/Prince William Sound region there are two types of transients: 

the AT1 group, a genetically separate group currently numbering 12 whales which specializes 

on harbor seals, and the less known Gulf of Alaska transients (whose population size is 

unknown although at least 60 whales have been identified so far), which appear to specialize 

on Steller Sea Lions. 

From data on killer whale stomach contents, observations of attacks and 

circumstantial evidence collected by various authors, it has become clear that killer whales 

may exercise a significant predation pressure on already depleted populations such as Steller 

sea lions and harbor seals in Alaskan waters. In turn, the depletion of key prey populations 

may result in a shift in diet by the predator or other alterations in the predator’s life style. In 

light of this, the study of such interactions is vital to the understanding of the population 

dynamics of both the predator and the prey. 

From the urgent perspective of addressing the causes of Steller sea lion decline, it 

is necessary to move past the realization that killer whales do prey on them and attempt to 

quantify the significance of this predation. It is also important to realize that predation 

pressure by killer whales may vary by rookery, by geographic locale and by time of year. 



92

The lack of understanding of transient killer whale ecology is due to the difficulties 

inherent in finding and tracking an animal that is elusive by nature (because of its predatory 

strategies) and its apparently wide range which has been estimated to be 180,000 square 

miles. 

In an attempt to monitor transient killer whale behavior near the Chiswell Island 

rookery we are using a series of remotely operated cameras located on the island. The signal 

from these cameras is sent via microwaves to an antenna on the roof at the ASLC and to a 

series of televisions in the research area where researchers monitor and record SSL behavior. 

In addition to the camera system, two hydrophones are constantly transmitting the underwater 

sounds around Chiswell Island to the ASLC. Using a combination of video and sounds, we 

have been able to monitor killer whale activity in the vicinity of Chiswell Islands and we 

hope, in the near future, to be able to capture on both audio and video the predation activity of 

transient killer whales in this area. 

Between 2000 and 2001 we have been able to remotely detect the presence of a 

single transient killer whale which frequents the Chiswell Island rookery with some 

regularity. AT109 is a transient killer whale which was first photographed in 1987 in nearby 

Prince William Sound. Since she has never been sighted with a calf, it is suspected she may 

beyond reproductive age (40 or more). Based on remote monitoring of the video cameras, 

AT109 visited Chiswell Island during at least 19 time slots encompassing periods of one to 11 

consecutive days patrolling the rookery between 2000 and the beginning of 2002. Many of 

these dates have also been confirmed by reports from tour operators in the Kenai Fjords area 

some of whom know AT109 well, and by our own surveys by boat. The whale’s activity near 

the rookery is concentrated in the late summer when sea lion pups are starting to swim. 

Interestingly, this summer AT109 was no longer alone but was swimming with 

another female and her calf. In the company of this female she altered her behavior and 

although she did visit the Kenai Fjords area, she was never seen at Chiswell Island, but at a 

different Steller sea lion haul out near Cape Resurrection. This raises some interesting 

questions such as whether the number of whales in a group may be a factor in determining the 

hunting strategy of the group, or whether individual whale preferences may influence prey 

choice to the point that social relationships shape the hunting strategy of a group or, again, 

whether the population size at the Chiswell Island haul-out is too small to support three killer 

whales versus only one. 

Steller sea lion mother/pup pairs found on Chiswell Island throughout the pupping 

season, are monitored around the clock and censused hourly by ASLC scientists. When a 

mother is censused without her pup on several occasions the pup is presumed lost. If we 

believe that killer whale AT109 preys on Steller sea lion pups, her rate of predation on this 

age class can be inferred from their reduced numbers after AT109’s visits, and especially by 

the confirmed loss of a pup by a known sea lion mother still present at the rookery after the 

whale’s visit. In late July 2001, daily sea lion pup numbers at Chiswell Island averaged 50 (± 

1 S.E.) during four days prior to a nine-day visit by AT109 and dropped to 38 (± 1 S.E.) 

afterward; a significant decline of 24% (U = 218.5, P < 0.001). During the same period in 

2000, when no killer whale was present near the rookery there was no change in pup numbers 

(U=34.5, P > 0.10). In addition, out of 31 identifiable mothers with pup being monitored daily 

from the video cameras, only 27 still had their pups after AT109’s visit (a 14% decline). 

During a six-day, late August visit by AT109 to the rookery, an increase in overall 

pup numbers was presumably caused by an influx of sea lions from a nearby rookery. Yet, of 

known female sea lions with pups during that time, 13% had lost their pup during the orca’s 

visit. 

On one occasion we intercepted AT109 in the vicinity of the rookery after 

noticing her presence on the video camera. In addition to her movement patterns around the 



93

ookery we recorded 111 dives during 3 ½ hours of observation. The pattern was consistent, 

with several short dives (one minute or less) followed by longer dives (up to 10 minutes). 

Dive times were longer near the rookery (< 500 m) as the whale patrolled the haul-out back 

and forth underwater, and shorter away from the rookery, but the difference was not 

significant (U=1624, P =0.169). Although we did not witness any predation event while 

following AT109, predation appears to have occurred during that same visit, which lasted six 

days, based on reports from one reliable tour operator who witnessed a kill. Judging from the 

whale’s behavior and dive pattern it is possible that predation events occur underwater. 

Data here presented support the possibility that predation pressure by one killer 

whale at Chiswell Island may have resulted in a predation rate on Steller sea lion pups as high 

as 13-24% in 2001. If this is the case, one single killer whale preying regularly on a rookery 

as small as Chiswell Island may exert a significant impact on its recovery. 



94

ANATOMY OF A LONG-TERM STUDY: POPULATION ECOLOGY OF KILLER 

WHALES IN PRINCE WILLIAM SOUND AND KENAI FJORDS, ALASKA 1983- 

2002. 

Craig Matkin, Graeme Ellis, Eva Saulitis, Lance Barrett Lennard, Harald Yurk, Kathy Heise, Peter 

Olesiuk 

North Gulf Oceanic Society, 60920 Mary Allen Ave., Homer, Alaska 99603, comatkin@xyz.net 

In choosing a study design we elected to use methodology that did not involve 

systematic vessel transects, but was based on finding “hotspots” where we could maximize our 

chances of encountering whales through opportunistic encounters using a local sighting network 

that was developed during the study. This allowed the use of small boats, but sometimes 

necessitated waiting for encounters. All aspects of the study were based on photoidentification 

or every individual. Our population estimates are all minimums based on photoidentified 

individuals only. The study is by necessity long term and emphasizes all aspects of live history 

of the animals. The study area for our core project is Kenai Fjords and Prince William Sound 

(Figure 1). What I present here, is a synopsis and overview of the project, several other talks 

will detail aspects of the project I touch on here. 

Figure 1 : Study Area 

The field components of this study included: 

• Photoidentification of every individual 

• Recording whale and vessel tracklines 

• Whale behavior by time and location 

• Acoustic recordings 

• Biopsy sampling 



95

skin for genetics 

blubber for contaminants 

• Monitoring of vessel interactions with whales 

• Prey observation and sample collection 

Our first and most important tool, photoidentification, has been used to determine the total 

number of killer whales that used the study area over the period of 18 years. It also gives a 

reasonable indication of the frequency with which each group used the area and the patterns 

of use, at least seasonally. 

Repeated photography of the major resident pods over a period of 10 years provided the 

data for the analysis of associations between individuals and resulted in the creation of 

genealogical trees for each matriline. Now after 18 years, or approximately one killer whale 

generation, we are developing a comprehensive population model for the well known resident 

pods. This includes mortality rates by sex and age, age estimates by various methods, calving 

intervals and fecundity rates, and rate of onset of post-reproduction in females. This 

information is incorporated into a matrix model and life tables. 

Photoidentification is also essential for our genetic analysis. Every biopsied whale is 

photographed and identified at time of sampling to determine population affiliation of its 

group or pod and to investigate social structure and breeding systems. Both mtDNA and 

nuclear DNA analysis have been used in the investigations. Accurate identification is also 

important in to interpret contaminant analysis where varying levels of contaminants can be 

traced to particular age and sex classes of whales. When documenting feeding habits 

photoidentification also provides the identity and population affiliation of the whales 

observed. Feeding habits vary by group and population. 

We are now using a Nobletech system integrated with the ships GPS that maps the vessel 

track as well as the trackline when with whales. Behaviors are linked to time and location on 

a nautical chart. This allows the analysis of the whale’s patterns of use within the study area. 

Directional hydrophones are used to locate whales and complement the visual search and 

observer networks. Whales are recorded after identifications are made and each various pods 

(residents) and populations can be identified by their calls. Our call catalogues allow 

identification of whales from calls alone. Calls recorded from remote hydrophones yield 

information on the identities of the whales that use the area in winter when fieldwork is 

difficult or impossible. Acoustics provide a shorter term picture of relationships between 

whale groups which complements the historic view offered by genetic analysis. 

Biopsy sampling is conducted using Pneudart air powered rifle and lightweight aluminum 

darts. The velocity is adjustable and samples are typically 5mm indiameter and 30mm in 

length and consist of skin and blubber. Genetic analysis confirms that the separation of 

residents and transients is a long standing, population level separation. In addition it has 

indicated that pods are not inbred; fathers of calves are apparently very distantly related to the 

mothers and are not found within the natal pod of the calf. Separation of subpopulations 

within resident and transient ecotypes has also been possible. Genetic analysis has shown two 

non-associating transient populations exist within our study area, the AT1 group and the Gulf 

of Alaska transients. Although we have considerable information on the rapidly declining 

AT1 transient population, the Gulf of Alaska transients appear to be a small, widely 

distributed population that has been difficult to study. Genetics has also revealed that the 

mitochondrial haplotypes for both the southern residents and the northern residents exist in 

the Prince William Sound These genotypes are specific to particular pods which can be 

separated into two acoustic clans. It is likely that two founding events occurred following the 

last ice age in southern Alaska. 



96

Blubber from biopsy samples were analyzed for PCBs and DDTs using HPLC/PDA 

method. It was found that transients have 15-20 times higher contaminant levels than 

residents, apparently due to their position higher on the food chain. In both populations 

lowest levels were found in reproductive females due to loss of contaminants via lactation 

(passed on to the calves). Highest levels were found in first born offspring, particularly older 

males that were unable to transfer contaminants via lactation. PCB levels in transients 

averaged over 250ppm total PCBs and 350 total DDTs with much higher levels in specific 

individuals. 

Finally, we have examined feeding habits by collecting scales from fish kills or prey 

pieces or by visual observation of prey within the mouths of the whales. When unsure if a kill 

took place (no physical evidence or clear observation) the interaction was treated as an 

harassment. Specific salmon species were targeted by the resident whales. In the July- 

September period silver or coho salmon are the primary prey while in the May-June period it 

appears that king or Chinook salmon are the primary prey, although samples from that period 

have not been completely analyzed. We suspect that king salmon are also important during 

the winter months. 

The AT1 transient diet is focused on harbor seals and Dall’s porpoise (with no 

predation on Steller sea lions). Although we have only a few feeding observations of the 

Gulf of Alaska transients, most are from two groups of animals ( 7 individuals) and are not 

necessarily representative of the entire population. These whales seem to specialize in 

predation on Steller sea lions, an endangered species in our region. One of the current 

research tasks is to determine how many of the Gulf of Alaska transients actually feed on sea 

lions and what the impact may be on the population of sea lions. Conversely, the decline of 

Steller sea lions may be having a significant impact on these transient killer whales. 

In summation: 

• By choice and necessity we used a small boat based surveys within a limited study 

area 

• Integrated approach-- all aspects are based on photoidentification of each individual 

which is essential for the other aspects of the study. 

• Long-term study is necessary to understand population dynamics (15 yrs+) and 

monitor annual changes (ie changes due to the Exxon Valdez Oil Spill) 



97

KILLER WHALE POPULATION BIOLOGY AND FEEDING ECOLOGY IN 

SOUTHEASTERN ALASKA. 

Matkin D. 1 , Sautilis E. 2 . 

1 PO Box 22, Gustavus, Alaska, USA 99 826, denamatkin@hotmail.com 

; 2 60920 Mary Allen Ave Homer, Alaska, USA 99603 

Killer whale (Orcinus orca) populations in southeastern Alaska have been photoidentified 

since 1984 (Leatherwood et al. 1984). Year-round work in the Glacier Bay/Icy 

Strait area began in 1988, and research efforts here have increased steadily up to the present 

(Matkin 1990). The study area is in the northern portion of southeastern Alaska and primarily 

includes Glacier Bay and the contiguous waters of Icy Strait and Cross Sound (Fig.1). Prince 

William Sound is to the north and British Columbia to the south. 

This paper presents a synthesis of the results of a 14-year study. It mainly includes 

photo-identification and feeding data from 1988 through 2001 collected by this author plus 

data collected by biologists working for Glacier Bay National Park and Preserve. In northern 

southeastern Alaska, we have identified 92 residents, 144 transients, and 14 individuals out of 

a pod of about 30 offshores. Populations that inhabit Prince William Sound, Alaska and 

populations that frequent British Columbia, Canada overlap in southeastern Alaska. 

Residents and transients have been reproductively isolated from one another for 

thousands of years, although they travel and forage through the same waters. The offshores 

are more closely related to the residents and are found in large fish-eating groups of about 30 

individuals (Matkin et al. 1999). The transients are mainly divided into AT1 transients (from 

Prince William Sound), Gulf of Alaska transients and West Coast transients. West Coast 

transients are the most commonly encountered type in Glacier Bay and Icy Strait. In 2001, 

two Gulf of Alaska transient males were documented swimming in Glacier Bay with West 

Coast transients for the first time. However, it is not known if the two types interbreed. 

From the pioneering photo-identification work of Dr. Mike Bigg in British Columbia, 

we know that residents form large stable matrilineal pods that eat fish, vocalize frequently, 

have more hooked dorsal fins and more black inside their white saddle patches (Bigg et al. 

1987). Several pods can join and form super-pods of over 100 individuals. The two main 

resident pods in southeastern Alaska (AF and AG pods) are most closely related to the 

northern residents of British Columbia. 

AF and AG pods travel regularly between southeastern Alaska and Prince William 

Sound, Alaska, and they intermingle most frequently with the Prince William Sound resident 

pods that are also most closely related to the northern residents of British Columbia. AF 

individuals made two visits to Prince William Sound in two months, and they traveled north 

750 km in just four days. These late July and August multi-pod associations are when coho 

salmon (Onchorhynchus kisutch) runs are at their peak, and social and sexual activity at these 

times indicate that successful matings occur (Matkin et al. 1997). AF and AG pods share 

many of the same discrete calls with each other as well as with Prince William Sound pods, 

further indicating a genetic relationship among these resident pods. 

AG pod has been photographed in southeastern Alaska every month of the year 

(sometimes at the faces of tidewater glaciers). AG pod consists of 29 individuals that feed on 

salmon and Pacific halibut (Hippoglossus stenolepis). AG pod females with young juveniles 

harassed to injury a common loon (Gavia immer) and harassed into flight a pigeon guillemot 

(Cepphus columbia). If residents mill, splash or breach close to humpback whales 

(Megaptera novaeangliae), humpbacks react with wheeze-blows, pectoral fin slaps, breaches, 

or rapid travel in the opposite direction. 

This study mainly focused on West Coast transients, 130 of which were photoidentified 

in the Glacier Bay/Icy Strait study area. These transients range a minimum of 2600 



98

km from southeastern Alaska, south to California (Goley and Straley 1994). The same 

transient individuals have been documented traveling a distance of 700 km from the Glacier 

Bay area to British Columbia 3 times in less than 10 months (Ford and Ellis 1999). They 

forage primarily for harbor seals (Phoca vitulina) from inter-tidal lagoons to the icebergs at 

the faces of the tidewater glaciers where harbor seals give birth to their pups in May and begin 

to wean them in June. Traveling and foraging in groups of one to 23 individuals, transient use 

of Glacier Bay peaks in June and July each year. 

A line graph (Fig.2) of the minimum number of transient individuals identified each 

year in the Glacier Bay/Icy Strait study area shows an average of 40 transients per year. The 

early years on this graph indicate increasing effort. The dip in 1991 has to do with problems 

with data analysis that year, and the peak in year 2000 is in part due to more effort. 

Identifications since 1992 are thanks to Graeme Ellis at the Pacific Biological Station in 

Nanaimo, British Columbia. 

The transients that hunt in the Glacier Bay region use it on a very regular basis. Some 

of the individuals have been documented in regular associations for more than a decade. T85 

is a cow that has been photo-documented every year (between June and September) since 

1988. She had a calf in 1992 and another in 1995, and was identified in the Glacier Bay area 

5 times in June of 2000 with both of these offspring. One of her preferred hunting partners is 

T40, an adult male she has been in frequent association with since 1988. T40 was the first 

animal photo-identified in this study, and he has been photo-identified in the study area from 

June through October every year since 1986 except two. T87 is another adult male transient 

that has been photo-identified in association with his constant hunting partner T88. Since 

1988, they have been in Glacier Bay between May and September every year but two. 

Representing 33 kill incidents, a pie chart (Fig.3) of percents of prey species taken by 

transients shows that at 43%, the harbor seal (Phoca vitulina) is the primary prey in the 

Glacier Bay/Icy Strait region. Harbor porpoise (Phocoena phocoena) come second, and 

combined with Dall’s porpoise Phocoenoides dalli) are 27% of prey taken. Seabirds are 15%, 

Steller sea lions (Eumetopias jubatus) 12% and minke whales (Balaenoptera acutorostrata) 

3% of West Coast transients’ diet. 

Attacks on harbor seals included all killer whale age and sex groups and lasted from 5 

minutes to 2 hours. Transient groups that killed seals ranged from 2 to 14 individuals, 

averaging 5 individuals. In 50% of seal kills, there was just milling with no surface activity. 

In the other 50%, they lobtailed on the seal first, sometimes up to 6 times. They rubbed 

against seals and carried them in their mouths before killing them. Seals that hid alongside or 

under the boat were caught and carried away from the boat. One seal climbed into the 

research boat to escape being eaten. After seal kills, transients may spyhop, breach or lobtail. 

In British Columbia, John Ford et al. (1998) found harbor seals to be the primary 

transient prey as well, representing 53% of the West Coast transient diet. In Prince William 

Sound, Eva Saulitis et al. (2000) found harbor seals (31%) second to Dall’s and harbor 

porpoise (45%) in those transients’ diet. 

In Glacier Bay/Icy Strait, harbor porpoise represented all but one of the porpoise kills. 

the british columbia study showed dall’s and harbor porpoise combined made up 23%, which 

again is similar to glacier bay (27%). groups of 3 to11 killer whales attacked porpoise from 

20 minutes up to 3 hours. all age and sex transients close pursued, repeatedly caught and 

released, hit porpoise into the air and carried them skinned in their mouths. After porpoise 

kills, they may leave behind lungs, heart, and in one case an almost whole skinned skeleton. 

After successful kills, transients may breach, have erections, spyhop, pectoral fin and tail slap, 

headstand and vocalize. 



99

Some seabirds in Glacier Bay become easy prey for transients when the birds molt in 

mid-summer, losing their flight feathers and rafting into groups of hundreds of flightless 

birds. Surf, white-winged and black scoters (Melanitta perspicillata, M. fusca, M. nigra) are 

primarily eaten, followed by common mergansers (Mergus merganser). Transients also 

harassed marbled murrelet (Brachyramphus mormoratus), common murre (Uria aalge) and 

pelagic cormorant (Phalacrocorax pelagicus). 

Groups of 3 to 7 females and young chased, bubbled under, hit into the air, lobtailed, 

lunged and breached on, repeat caught and released birds. After seabird kills, transients may 

spyhop, breach or lobtail. Whereas seabirds represented 15% of kills in Glacier Bay, they 

were only 6% in British Columbia, where in 3 out of 8 seabird kills, the carcass was 

abandoned, and there were more than twice as many harassments than kills. In British 

Columbia, common murre were primarily chosen. No attacks on birds were seen in Prince 

William Sound. 

Sea lions represented 12% and 13% of transient predation in the Glacier Bay and 

British Columbia studies, respectively. Sea lions represented 15% of the transient diet in this 

author’s previous feeding study (Matkin and Dahlheim 1995) and in Lance Barrett-Lennard’s 

study on “The impact of killer whale predation on Steller sea lion populations in British 

Columbia and Alaska,” (Barrett-Lennard et al. 1995). In all areas, transients ignored or just 

harassed sea lions more than twice as often than they achieved successful kills. All age and 

sex killer whales participated in sea lion kills in group sizes of 4 to 6 individuals. 

Attacks lasted 15 to 65 minutes in which killer whales chased, breached on, tail 

slashed, dorsal slapped, pushed, rubbed against, hit sea lions into the air, carried them in their 

mouths or held them underwater. Sea lions responded by porpoising rapidly away, playing 

dead at the surface or attempting to inflict injury with teeth, nails and a ferocious disposition. 

Sea lion individuals smaller than adult males were chosen for prey items. After these long 

attacks with more surface activity needed to subdue the Steller sea lion, transients may breach 

with erections, spyhop, lobtail, pectoral fin slap and vocalize. Humpback whales investigated 

these attacks by rubbing past or lightly tail-slapping the sea lion and mingling with the killer 

whales underwater. 

Only one minke whale kill occurred in the study area, lasting 90 minutes. Thirteen 

transients lead by an adult male chased, surrounded, rammed and bit the minke’s underside 

and blocked its escape. It ultimately bled to death and sank. A single humpback whale came 

over to investigate the attack twice, whereupon the lead transient male rammed it broadside. 

The humpback defended itself by turning on its back and thrashing its tail up and down. 

Humpback whales also responded to transients’ close proximity by ignoring them, leaving the 

immediate area, having longer dive times, pectoral fin slapping, breaching, groaning, wheezeblowing 

and vocalizing. 

Large whale kills are considered uncommon or rare in British Columbia, and have 

never been documented in Prince William Sound. Since large portions of the large whales are 

not eaten, these episodes may occur to reinforce cooperative social bonds among transients, 

and provide practice sessions for their young. Out of 12 humpback whale attacks worldwide, 

8 occurred in southeastern Alaska and none were confirmed kills. Killer whale group sizes 

ranged from 1 to 17, attacks included all age and sex groups, lasting from 26 minutes to 4 

hours. Killer whales cooperated by keeping humpback adults separate from their calves 

(Sharpe 1990). 

Attacks on minke whales worldwide were more successful. Out of 8 attacks, all died. 

All killer whale age and sex groups participated in groups of 3 to 15 individuals. Attacks 

lasted 30 minutes to 3 ½ hours, and were frequently described as calm and deliberate. Minkes 

that could not escape did not fight back. They were pulled underwater, bitten, skinned, and 

had their tongue, jaw, baleen, blubber and ribs eaten (Hancock 1965). 



100

Most large whale kills from Mexico to Alaska were of gray whales (Eschrichtius 

robustus). Four transients identified in Glacier Bay in 1989, were identified killing gray 

whale calves off Monterey, California in 1992. Out of 9 kills along the west coast, 5 were of 

calves. Eight attacks resulted in escape. Both attacks and successful kills were lead by adult 

males or females with young. In groups of 2 to 17, killer whales attacked gray whales from 1 

½ to 5 ½ hours (Baldridge 1972). After taking turns attacking, killer whales may depart the 

area up to 35 minutes, then return to eat and vocalize. They eat tongue, jaw, rostrum, baleen, 

mandible, thorax and ventral surface blubber. Gray whales sometimes escaped attack by 

remaining motionless at the surface, retreating to shallows and kelp beds, exhaling below the 

surface, forming compact groups and calves climbing onto their mothers’ head (Marks 1998). 

A lack of predatory behavior of killer whales toward sea otters (Enhydra lutris) was 

noted in British Columbia, southeastern Alaska and Prince William Sound studies. Normal 

behavior for both residents and transients was to pass by or under sea otters with neither 

species seeming to notice the other. During 13 encounters in Glacier Bay or Icy Strait, with 

both residents and transients, this was the case. In 3 other encounters, sea otters reacted to 

residents’ spyhopping, and transients’ milling within 20 meters. Sea otters reacted by diving 

and resurfacing inside the kelp, looking around, or porpoising and diving away from the killer 

whales. Two Gulf of Alaska transient males identified in Glacier Bay in 1998 passed by 75 

sea otters (some singles, some mothers with pups) with no visible interactions. 

Unidentified killer whales also took and ate a swimming moose (Alces alces) in Icy 

Strait in 1992. They tried unsuccessfully to scare a second moose out of a nearby kelp bed, 

but they soon gave up, and the second moose later entangled itself in the kelp and drowned. 

Transients in Prince William Sound harassed (by chasing) salmon on one occasion, and 

transients in Glacier Bay/Icy Strait harassed salmon on two occasions. 

Although the wide variety of prey presented here for transients indicates that they can 

be opportunistic, the actual diet of each small sub-group of transients may be more simple. It 

reflects a combination of prey resource availability in a given area and cultural transmission 

of specific hunting skills for that prey. Killer whale diet overall is the result of behavior 

learned within a structure of deep social bonds which is passed from one generation to the 

next. 

REFERENCES 

Baldridge, A. 1972. Killer whales attack and eat a gray whale. Journal of 

Mammalogy 53: 898-900. 

Barrett-Lennard, L., K. Heise, E. Saulitis, G. Ellis and C. Matkin. 1995. The impact 

of killer whale predation on Steller sea lion populations in British Columbia and Alaska. 

Report for the North Pacific Universities Marine Mammal Research Consortium Fisheries 

Centre, University of British Columbia, Vancouver, B.C. 

Bigg, M.A., G.M. Ellis, J.K.B. Ford and K.C. Balcomb III. 1987. Killer Whales: A 

study of their identification, genealogy and natural history in British Columbia and 

Washington state. Phantom Press and Publishers, Inc., Nanaimo, B.C. 79 pp. 

Ford, J.K.B. and G.M. Ellis. 1999. Transients: Mammal-hunting killer whales. UBC 

Press, Vancouver, B.C. 

Ford, J.K.B., G.M. Ellis, L.G Barrett-Lennard, A.B. Morton, R.S. Palm and K.C. 

Balcomb III. 1998. Dietary specialization in two sympatric populations of killer whales 



101

(Orcinus orca) in coastal British Columbia and adjacent waters. Canadian Journal of Zoology 

76: 1456-1471. 

Goley, P.D. and J.M. Straley. 1994. Attack on gray whales (Eschrichtius robustus) in 

Monterey Bay, California, by killer whales (Orcinus orca) previously identified in Glacier 

Bay, Alaska. Canadian Journal of Zoology 72: 1528-1530. 

Hancock, D. 1965. Killer whales kill and eat a minke whale. Journal of Mammalogy 

46: 341-342. 

Leatherwood, S., K.C. Balcomb III, C. Matkin and G. Ellis. 1984. Killer whales 

(Orcinus orca) of southern Alaska. Hubbs Sea World Research Institute Technical Report 

No. 84-175. 59 pp. 

Marks, J. 1998. Two calves killed on migration through bay. The Monterey County 

Herald (April 22, 1998). 

Matkin, D.R. 1990. Killer whales in Glacier Bay and Icy Strait, Alaska. In: A.M. 

Milner and J.D. Wood, Jr. (Eds.), Proceedings of the Second Glacier Bay Science 

Symposium, 1988. National Park Service, Anchorage, Alaska. pp. 96-100. 

Matkin, D.R. and M.E. Dahlheim. 1995. Feeding behaviors of killer whales in 

northern southeastern Alaska. In: D.R. Engstrom (Ed.), Proceedings of the Third Glacier Bay 

Science Symposium, 1993. NPS, Anchorage, Alaska. pp.246-253. 

Matkin, C.O., D.R. Matkin, G.M. Ellis, E. Saulitis and D. McSweeney. 1997. 

Movements of resident killer whales between southeastern Alaska and Prince William Sound, 

Alaska. Marine Mammal Science, 13 (3) (July 1997). 

Matkin, C.O., G.M. Ellis, E. Saulitis, L.G. Barrett-Lennardand D.R. Matkin. 1999. 

Killer whales of southern Alaska. North Gulf Oceanic Society, Homer, Alaska. 

Saulitis, E., C. Matkin, L. Barrett-Lennard, K. Heise and G. Ellis. 2000. Foraging 

strategies of sympatric killer whale (Orcinus orca) populations in Prince William Sound, 

Alaska. Marine Mammal Science 16 (1): 94-109. 

Sharpe, F.A. C.G. D’Vincent and R.M. Nilson. 1990. Interactions between orcas and 

cooperatively foraging humpback whales in southeastern Alaska. Abstract presented at the 

Third International Orca Symposium, Victoria, B.C. 



102

Figure 1 



103

80 

70 

60 

50 

40 

30 

20 

10 

0 

1984 

1986 

Glacier Bay/West Coast 

Transients Identified by Year 

1988 

1990 

Seabirds 

15% 

1992 

Figure 2 

1994 

Transient Prey by Percent 

in Glacier Bay/Icy Strait 

Minke Whale 

3% 

Steller Sea Lion 

12% 

Harbor/Dall's 

Porpoise 

27% 

Figure 3 

1996 

Harbor Seal 

43% 

1998 



2000 

104

UNRAVELING THE INFLUENCE OF SOCIAL STRUCTURE AND PREY TYPE ON 

VOCAL COMMUNICATION IN KILLER WHALES 

Miller P.. 

WHOI, MS#34; Woods Hole, MA 02543; USA, pmiller@whoi.edu. 

Killer whales are a cosmopolitan species with a wide range of different social structures 

that are strongly influenced by the temporal and spatial patterns of available prey. The 

diversity of social structures in this species offers a model to explore how social systems 

influence vocal behaviour and ontogeny through vocal learning. However, it is likely that a 

primary function of communication is to coordinate foraging behaviour, which will differ 

depending on prey-type, and sound production is affected strongly by the hearing abilities of 

prey (Barrett-Lennard et al. 1996). Therefore, a difficult but important challenge in comparing 

the vocal behavior of different killer whale populations will be to distinguish effects of prey 

behaviour and hearing sensitivity from effects of social structure. In addition to studies on 

prey hearing abilities, descriptions of the role of communication in foraging are needed. In 

residents, vocal behaviour is fairly well-described and the design and use of acoustic signals 

support Ford’s (1991) thesis that calling serves to maintain group stability and coordinate 

behavior, including foraging. However, because it is impossible to observe whales and their 

fish prey from the surface, we have no direct information on the role of acoustic 

communication in foraging. The social structure and sound production of herring-feeding 

killer whales off Norway appear quite similar to that of the salmon-feeding whales (Simila et 

al. 1996; Strager 1995). However, there are likely to be important differences in how group 

members coordinate behavior, and role of communication, during foraging on this smaller 

schooling prey. In fish-eating species, underwater tracking of individuals and prey using tags, 

sonar and hydrophone arrays is needed to elucidate how sounds are used in foraging. The role 

of communication during foraging on mammal prey may be somewhat easier to study because 

such feeding is more conspicuous and closer to the surface. 



105

O. ORCA ABUNDANCE, DISTRIBUTION, SEASONAL PRESENCE, PREDATION 

AND STRANDINGS IN THE WATERS AROUND KAMCHATKA AND THE 

KOMMANDER ISLANDS: AN ASSESSMENT BASED ON REPORTED SIGHTINGS 

1992-2000 

Mironova A.M.(1), Burdin A.M.(2), Hoyt E.(5), Jikiya E.L.(3), Nikulin V.S.(1), Pavlov N.N.(1), Sato 

H.(4), Tarasyan K.K.(3), Filatova O.A.(3), 

Sevvostrybvod, Petropavlovsk-Kamchatsky, Russia (1) ; Kamchatka Institute of Ecology and Nature 

Managment Petropavlovsk-Kamchatsky, Russia (2); Moscow State University, Russia (3); Tokyo, 

Japan (4); WDCS, North Berwick, Scotland (5) 

In spite of wide-ranging O. orca presence in the waters of Kamchatka and the 

Commander Islands, published information is scarce due to the high cost and difficulty of 

working from ships in the North Pacific off far eastern Russia. In this work, we used Arc 

View software to analyze data about O. orca collected mainly by Sevvostrybvod surveyors 

and observers from 1992-2000 inclusive. Over 9 years, we report 274 encounters with 1,619 

animals around Kamchatka and the Commander Islands. O. orca seasonal presence was as 

follows: 14 encounters (61 animals) during the winter period, 44 encounters (196) in spring, 

126 encounters (726) in summer and 90 encounters (636 animals) in autumn months. 

However, without the calculation of level of effort throughout the year, the seasonal O. orca 

distribution is only approximate. Most common group size was 2-5 individuals (42.5% of 

encounters), while lone animals were 13.3% of encounters. The largest group consisted of 57 

individuals. As a rule, observers do not report the sexual composition of groups. 

Kamchatka peninsula: 

Most often, O. orca were found in areas along eastern Kamchatka with intensive marine 

traffic from the cape Bezymiannyi on the north to the cape Piratkov in the south (37 sightings 

of 507 animals) including Starichkov Island, bays Sarannaya, Viluchinskaya, Jirovaya, 

Falshivaya, Russkaya, Asacha and the capes of Opasniy, Kekurniy, Piramidniy, Polosatiy; in 

the region of cape Shipunskiy (4 sightings of 31 animals), Vestnik bay (15 sightings of 48 

animals). 

. There were 7 reported events of O. orca predation on sea mammals including walrus, 

Odobenus rosmarus, northern fur-seal, Callorhinus ursinus, , two attacks on northern minke 

whale, Balaenoptera acutorostrata, and three attacks on humpback whales, Megaptera 

novaeangliae. A total of 4 O. orca carcasses were found: an adult male (1999), a young 

female (2000) and two O. orca of unknown sex and age (1997 and 1999). 

Commander Islands: 

Here, O. orca are most often observed around northern fur seal (Callorhinus ursinus) 

rookeries; the most reported sightings were around capes Yushina (7 sightings of 18 orcas), 

Severo-Zapadnyi (4 sightings of 10 animals), South-east rookery (9 sightings of 94 animals), 

bays Nikolskaya (8 sightings of 23 orcas), Poludennaya (6 sightings of 94 orcas) and 

Gladkovskaya (6 sightings of 9 animals). 

There were 3 recorded events of O. orca predation on marine mammals, twice on 

northern fur-seals, Callorhinus ursinus. Two dead adult O. orca: male (1994) and female 

(1997) were found on Bering Island. 

In addition, off Kamchatka, since 1999, O. orca have been preying on Pacific halibut, 

Hippoglossus stenolepsis and black halibut, Reinchardtins hippoglossoides, stealing from the 

bottom nets and longlines of fishermen. The scale of the damage has increased annually, and 

this problem requires urgent attention. 



106

On the basis of these reported sightings alone (without considering current photo-ID 

or other work on O. orca), a preliminary estimate of abundance in summer for both 

Kamchatka and the Commander Islands would be at least 700-800 animals. 



107



108

KILLER WHALES (ORCINUS ORCA) IN AUSTRALIAN TERRITORIAL AND 

SURROUNDING WATERS – ARE THEY SECURE ? 

Margie Morrice 1 , Catherine Bell 1 , John van den Hoff 2 , Debbie Thiele 1 , Peter Gill 1 , Dave Paton 3 , 

Magaly Chambellant 4 

1 School of Ecology & Environment, Deakin University, PO Box 423 Warrnambool, VIC 3280, 

Australia 

2 Australian Antarctic Division, Channel Hwy, Kingston TAS 7050, Australia 

3 Southern Cross Centre for Whale Research, Noosa, QLD, Australia 

4 Centre D’etudes Biologiques De Chize – CNRS, 79360 Beauvoir-sur-Niort, France 

BACKGROUND 

Australian waters contain a diverse array of marine habitats. The 11 million sq km of 

ocean under Australian jurisdiction extends from warm tropical waters to the coldest 

Antarctic waters. The area consists of Exclusive Economic Zones (EEZs) extending 200 

nautical miles from the Australian continent, Tasmania and its offshore islands - Christmas 

Island, the Cocos and Keeling Group, Lord Howe Island, Norfolk Island, Macquarie Island, 

and the Territory of Heard Island and McDonald Islands. The waters off the Australian 

Antarctic Territory (AAT) are managed in accordance with the requirements of CCAMLR of 

which Australia is a leading member. The region supports locally productive marine 

communities that provide for a number of large marine predators including pelagic fish, 

sharks, squid, and toothed whales, the largest being sperm whales (Physeter macrocephalus) 

and killer whales (Orcinus orca). 

Killer whales are often described as cosmopolitan in distribution, and the published 

literature for the Australian region supports this to some extent. Sightings of killer whales 

have been documented from most Australian states and territories, with the southern regions 

(South Australia, Victoria, Tasmania and Antarctic) having support from cetacean reporting 

programs (Cotton 1943, Chittleborough 1953, Aitken 1971, Guiler 1978, Parker 1978, TFDA 

1981, McManus et al. 1984, Anderson & Prince 1985, Nicol 1986, Kemper and Ling 1991, 

Ling 1991, Copson 1994, Dixon and Frigo 1994, Gill and Thiele 1997, Stewardson and Child 

1997, Thiele and Gill 1999, Chatto and Warneke 2000, Shaughnessy 2000, Janetzki and 

Paterson 2001, Morrice and van den Hoff 2001, Paterson and Paterson 2001). However, many 

records remain unpublished. 

It was recognised that there would be value in bringing together the unpublished 

information on killer whales for the Australian region to provide baseline information. This 

would allow assessments of trends in killer whale ecology such as distribution, evidence for 

migration and foraging, and which could put ‘Australian’ killer whale populations in a world 

context. This information would then be available to base and support conservation and 

management decisions for killer whales in Australian waters, and would provide a wider 

awareness of this species and its issues. 

METHODS 

Incidental records 

Information relating to killer whale sightings, strandings, museum specimens and 

fishery interactions were requested from Australian government agencies, museums, research 

institutions, non-government organisations and interested individuals. The management of 

this information varied from formal sightings and stranding databases to ad-hoc collections. 

These records were collected by observers with a range of cetacean observation experience as 



109

part of regular conservation and museum activities, field research, fisheries operations, other 

platforms of opportunity programs or recreational activity. As such, the level of detail and 

reliability of this information varied considerably. Any observable missing data or 

discrepancies in the data were queried and corrected. 

Records and anecdotal information, including reports of nil sightings, were obtained 

from the Museum and Art Gallery of the Northern Territory (NT), Queensland Museum 

(QLD), Queensland Parks and Wildlife Service (QLD), Queensland Boating and Fisheries 

Patrol (QLD), Rob Paterson (QLD), James Cook University (QLD), Sea World (QLD), New 

South Wales National Parks and Wildlife Service (NSW), Australian Museum (NSW), 

Southern Cross Centre for Whale Research (NSW), Macleay Museum - University of Sydney 

(NSW), Taronga Park Zoo (NSW), Biological Sciences - Museum Macquarie University 

(NSW), Environment Australia (ACT), Australian Fisheries Management Authority (ACT), 

CSIRO (ACT), Dept. Natural Resources and Environment (VIC), Museum Victoria (VIC), 

Australocetus Research (VIC), Marequus (VIC), Deakin University (VIC), LaTrobe 

University (VIC), Phillip Island Nature Park (VIC), Applied Ecology Solutions (VIC), K. Lott 

(VIC), Dept. Primary Industries Water and Environment (TAS), Tasmanian Museum and Art 

Gallery (TAS), University of Tasmania (TAS), Warneke Marine Mammal Services (TAS), 

South Australian Museum (SA), Dept. Conservation and Land Management (WA), West 

Australian Museum (WA), John Bannister (WA), Centre for Whale Research (WA), and 

Joanne Tilbury (WA). There are many other anecdotes, records, photographic and other 

material relating to killer whales for this region, however they are not easily accessible and 

will need collation in the future (eg. aerial and boat-based surveys for marine wildlife and 

surveillance). 

Macquarie Island sighting program 

A killer whale sighting program for Macquarie Island and its surrounding waters was 

initiated in 1994 (Morrice and van den Hoff 2001). Killer whales were recorded by Australian 

National Antarctic Research Expedition (ANARE) personnel onto specifically designed 

sighting sheets. This allowed records of sightings, behaviour and environmental information 

to be collected in a consistent and detailed manner, and extended to the collection of baseline 

photographic and behavioural catalogues. Additional historical information prior to 1994 was 

collated from station log books and expeditioner’s field note books. The reliability of this data 

is considered good, as the personnel were provided with killer whale identification guides and 

experienced marine mammal scientists were often on hand to help confirm and detail the 

sightings. Of all the observations relating to each sighting, only spatial and temporal data was 

assessed for this study. Behaviour, habitat-use and photo-identification information will be 

published separately. 

SOCEP program 

The Southern Ocean Cetacean Ecosystem Program (SOCEP, D. Thiele) has been 

conducting cetacean surveys in the AAT annually since the 1995 austral winter season. More 

recently the program has incorporated components other than visual survey (photo 

identification, biopsy and passive acoustics) and focussed effort on the multidisciplinary 

marine science voyages under what is now known as the Antarctic Marine Living Resources 

(AMLR program). SOCEP has conducted standardized annual cetacean surveys using 

experienced observers on-board a total of 17 ANARE voyages to the AAT (longitudinal range 

~70°E - 155°E ) between 1995 and 2001. A wide range of data were collected for all species 

encountered, including killer whales. 



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Southern Oceans Orca Database 

The Southern Oceans Orca Database (SOOD) was established to merge all the available 

Australian killer whale information into a uniform format for querying and analysis. Data 

exchange agreements were set-up to manage the ownership and future exchange of 

information between the interested parties. Environmental data, including bathymetry, 

coastline and marine jurisdictional boundaries, were accessed from Geoscience Australia. 

ArcView Geographic Information Systems software (ESRI, 1996) was used to display and 

analyse the sighting records. Remaining data was used to describe distribution, pod 

composition, other animals present, feeding and other behaviour including fishery 

interactions. The SOOD also summarises killer whale specimens that are currently held in 

institutions across Australia, including those that may be available for future analysis (eg. 

genetic, stomach contents, pollutant). 

RESULTS 

The results are preliminary. To date a total of 910 killer whale records have been 

collected from most regions in Australia (Figure 1). The majority of these records are 

incidental (793), and over 62% of all records were from Macquarie Island. Other regions 

where sightings are common include South Australia, Victoria, south-east Tasmania and in 

waters surrounding the Australian Antarctic Territory. These aggregations likely reflect 

increased killer whale activity combined with a disproportionate effort in recording sightings. 

No sightings have been recorded in the Australian territories of the Cocos Keeling Island 

Group, Christmas Island and the Heard and McDonald Island Group, however this does not 

mean killer whales are not there. 

Records for the tropical latitudes (0-25° S) are rare, mid-latitudes (25-50° S) are more 

common during the austral winter and spring, in the sub-Antarctic (50-60° S) there is a 

definite seasonal peak over the austral spring and summer months, and in Antarctic waters 

(60-80° S) killer whales are observed more commonly during the mid to late austral summer. 

In south-east Australian regions and at Macquarie Island the whales are seen all year round 

(Figure 2). 

Mean group size was approximately 4 (SD±3.07), ranging from 1 to 100. Mean group 

size for killer whales sighted in Antarctic waters was larger at approximately 6 (SD±5.15, 

range 1-60), and for Macquarie Island the mean was 4 (SD±1, range 1-20) whales per group. 

Some group size may have been under-estimated when the killer whales were widely 

dispersed. 

From the total number of killer whales seen around Macquarie Island at any one time, a 

minimum estimated population size of 20 was calculated. The typical group composition for 

this region is a single adult male with three females/juveniles. A photo-identification 

catalogue has recorded 13 individuals, with only one re-sight. This highlights the difficulty in 

collecting this type of information in extreme environments where shore-based observations 

dominate the data, and where dedicated research is lacking. 

The distribution of killer whale sightings correlates to areas where their prey are 

concentrated and fishing activities are seasonally active. These sightings are also probably 

biased by the increased reporting effort in these areas at these times. For the mid latitudes (25- 

50° S), killer whale sightings have been “naturally” associated with migrating humpback 

whales (Megaptera novaeangliae), sperm whales (Physeter macrocephalus), dugong (Dugong 

dugon) feeding areas, Australian and New Zealand fur seal breeding colonies (Arctocephalus 



111

pusillus doriferus, Arctocephalus forsteri), and large groups of bottlenose and common 

dolphins (Tursiops truncates sp., Delphinus delphis). An “artificial” association exists 

between killer whales and the dropline and longline fisheries for tuna. It is not known whether 

fish taken from these lines (bait, target and bycatch) form part of the natural diet of these 

whales. 

At Macquarie Island killer whales were most often sighted inshore during the peak 

breeding periods of southern elephant seals (Mirounga leonina) (particularly when weaned 

seals are learning to swim and leave their natal site for feeding grounds); New Zealand, 

Subantarctic and Antarctic fur seals (Arctocephalus forsteri, A. tropicalis, A. gazella); and 

king and royal penguins (Aptenodytes patagonicus, Eudyptes schlegeli). In the AAT waters 

killer whales were associated with minke whales (Balaenoptera acutorostrata), crabeater 

seals (Lobodon carcinophagus) and emperor penguins (Aptenodytes forsteri), all of which are 

known prey for killer whales. These killer whales have been observed with diatom films on 

their skin and a distinctive cape pigmentation on their dorsal surface. Other wildlife 

associated with killer whale groups include seabirds such as petrels, albatross, skuas, gulls 

and prions; and fish, dolphins, white sharks (Carcharadon carcharius) and false killer whales 

(Pseudorca crassidens). 

KEY ISSUES 

The current key issues for killer whales in waters under Australian jurisdiction include: 

− a lack of baseline knowledge, 

− conservation status and management approaches which do not reflect the current state of 

knowledge overseas, 

− potential changes in prey availability associated with over-fishing and global climate 

change, 

− direct fishery interactions, and 

− pollution ie. ingestion of marine debris and their susceptibility to accumulating high levels 

of heavy metals and organochlorines. 

The current conservation status, protection mechanisms and the management of 

information relating to killer whales in Australian waters reflects the paucity of available 

information in this region. In the Action Plan for Australian Cetaceans killer whales are 

defined under adopted IUCN categories as ‘insufficiently known‘ but ‘probably secure’, the 

only species of the 45 recognised cetacean taxa in Australian waters listed under this category, 

and which is based on estimates of this species in Antarctic waters (Bannister et al. 1996). 

Clearly, there is a requirement to take some positive action on the ‘insufficiently known‘ 

status for this species to more accurately determine its current status and future survival 

probabilities. 

Interactions between killer whales and fisheries are common to longline and dropline 

fisheries in south-east Australia. To some extent these interactions have been documented by 

dedicated fishery observers and to a lesser extent from anecdotal accounts by fishing crew 

(Tasmanian Fisheries Development Authority 1981, McManus et al. 1984, Bell et al. in press, 

Morrice unpublished data). 

The direct nature of this type of interaction is detrimental to both the fishery and the 

whales themselves. Among the effects of interactions are possible direct competition for food, 

changes in whale behaviour, damage to fish gear, increased time and effort to fill quotas; and 

direct mortality of whales from shooting, entanglement and drowning (Bell et al. in prep.). 

The stomach contents from a stranded young male killer whale in South Australia provides 



112

evidence that it had ingested pieces of at least three dolphin species (likely Delphinus delphis, 

Tursiops truncatus, unknown spp.) that had been cut with a knife. This suggests the dolphin 

had been used by a fisher as bait for the whale, whether to harm the whale or not is uncertain 

as the direct cause of death of this killer whale is unknown (Gibbs 2001). Recommended 

strategies to address the issue of fisheries interactions include a more detailed assessment and 

quantification of fishery interactions, and the development of mitigation measures based on 

experience and successful programs developed in Australia and overseas. 

Killer whales rarely strand. To date 3 mass and 16 single strandings have been 

confirmed. Although reporting of these events has improved with stranding networks and an 

increase in public awareness, opportunities for the collection of crucial scientific information 

are not maximised. The collection of sightings, photo-identification information from freeranging 

killer whales, post-mortem samples and the need for dedicated research at key 

locations such as Macquarie Island, the Australian Antarctic Territory, Coffs Harbour and 

Tasmania is critical to the future management of this species. 

REFERENCES 

Aitken, P. F. (1971). Whales from the coast of South Australia. Trans. R. Soc. S. Aust. 95(2): 95-103. 

Anderson, P. K. and Prince, R. I. T. (1985). Predation on dugongs: attack by killer whales. J. Mamm. 66 

(3): 554-556. 

Bannister, J. L., Kemper, C. M. and Warneke, R. M. (1996). The Action Plan for Australian Cetaceans. 

Australian Nature Conservation Agency. 242pp. 

Bell, C., Shaughnessy, P. Morrice, M. and Stanley, B. (in prep.). Marine mammals and Japanese long-line 

fishing vessels in Australian waters: interactions and other sightings. 

Chatto, Ray and Warneke, Robert M. (2000). Records of cetacean strandings in the Northern Territory of 

Australia. 

The Beagle, Records of the Museums and Art Galleries of the Northern Territory 16: 163-175. 

Chittleborough, R. G. (1953). Aerial observations on the humpback whale, Megaptera nodosa 

(Bonnaterre), with notes on other species. Aust J. Marine and Fresh. Res. 4: 219-226. 

Copson, G. R. (1994). Cetacean sightings and strandings at subantarctic Macquarie Island, 1968-1990. 

ANARE Research Notes 91. 

Cotton, B. C. (1943). Killer whales in South Australia. The South Australian Naturalist 22: 2-3. 

Dixon, J. M. and Frigo, L. (1994). The cetacean collection of the Museum of Victoria. An annotated 

catalogue. 

Australian Deer Research Foundation: Melbourne. 

Gibbs, Susan and Long, Martine (2001). Stomachs contents of a killer whale (Orcinus orca) implicate 

human 

interaction in South Australia. Poster paper for the Southern Hemisphere Marine Mammal Conference, 

Phillip Island, Australia. 

Gill, P. C. and Thiele, D. (1997). A winter sighting of killer whales (Orcinus orca) in Antarctic sea ice. 

Polar Biol. 17: 401-404. 

Guiler, Eric R. (1978). Whale strandings in Tasmania since 1945 with notes on some seal reports. Papers 

and Proceedings of the Royal Society of Tasmania 112: 189-213. 

Janetzki, H. A. and R. A. Paterson (2001). Aspects of humpback whale, Megaptera novaeangliae, calf 

mortality in Queensland. Memoirs of the Queensland Museum 47 (2): 431-435. 



113

Kemper, C. M. and Ling, J. K. (1991). Whale strandings in South Australia (1881-1989). Transactions of 

the Royal 

Society of South Australia 115(1): 37-52. 

Ling, J. K. (1991). Recent sightings of killer whales, Orcinus orca (Cetacea: Delphinidae), in South Australia. 

Trans. R. Soc. S. Aust. 15(2): 95-98. 

McManus, T. J.; Wapstra, J. E.; Guiler, E. R.; Munday, B. L. and Obendorf, D. L. (1984). Cetacean strandings in 

Tasmania 

from February 1978 to May 1983. Papers and Proceedings of the Royal Society of Tasmania 118: 117- 

135. 

Morrice, Margaret and van den Hoff, John (2001). Preliminary investigations of killer whales (Orcinus 

orca) from inshore waters around sub-Antarctic Macquarie Island. Society for Marine Mammalogy Twelfth 

Biennial Conference, Hawaii, 1999 (poster); and Southern Hemisphere Marine Mammal Conference, Phillip 

Island, Australia, May 2001(poster). 

Nicol, D. J. (1986). A review and update of the Tasmanian cetacean stranding record to the end of 

February 1986. Environmental Studies Working Paper 21. University of Tasmania. 93 pp. 

Parker, A. A. (1978). Observations of whales on ANARE voyages between Australia and Antarctica. 

Aust. Wildl. Res. 5: 25 39. 

Paterson, R. A. and Paterson, P. (2001). A presumed killer whale (Orcinus orca) attack on humpback 

whales (Megaptera novaeangliae) at Point Lookout, Queensland. Memoirs of the Queensland Museum 47(2): 

436. 

Shaughnessy, P. D. (ed.) (2000). Antarctic seals, whales and dolphins of the early twentieth century: 

Marine mammals of the Australasian Antarctic Exhibition, 1911-14 (AAE) and the British, Australian and New 

Zealand Antarctic Research Expedition, 1929-31 (BANZARE). ANARE Reports 142: 154 pp. 

Stewardson, C. L. and Child, P. L. (1997). Mammals of the ice: an introductory guide to the seals, whales 

and dolphins in the Australian subantarctic and Antarctica, based on records from ANARE voyages, 1977-90. 

Australian Antarctic Division, Hobart. Sedona Publishing, Canberra. 183 pp. 

Tasmanian Fisheries Development Authority (1981). Assessment of impact of interference from Orcinus 

orca (killer whale) on Tasmanian dropline fishery: preliminary report. Consultancy report for the Australian 

National Parks and Wildlife Service, Tasmania. 11 pp. 

Thiele, D. and Gill, P. C. (1999). Cetacean observations during a winter voyage into Antarctic sea ice 

south of Australia. Antarctic Science 11(1): 48-53. 

. 



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Figure 1. Distribution of killer whale sightings and strandings from both incidental and on-effort records for the 

Australian territorial region. Lines represent the 200 nm limit of waters under Australia’s jurisdiction 



115

Figure 2. Seasonal and latitudinal patterns in killer whale sightings for the Australian territorial region. 



116

LIFE HISTORY AND POPULATION DYNAMICS OF RESIDENT KILLER 

WHALES IN ALASKA 

Olesiuk, Peter F. 1 , Craig O. Matkin 2 , Graeme M. Ellis 1 , and Eva L. Saulitis 2 

1 Department of Fisheries and Oceans, Pacific Biological Station, Nanaimo, B.C., Canada V9R 5K6; 

2 North Gulf Oceanic Society, 60920 Mary Allen Avenue, Homer, Alaska, USA 99603 

Life history parameters were derived for resident killer whales in Alaska based on longterm 

photo-identification studies. Field work was conducted annually during 1984-2001 in 

the waters between the Kodiak Archipelago and SE Alaska, but was concentrated in PWS / 

Kenai Fjords during summer months. Although the total population numbers in excess of 450 

whales, our analysis was based on the 10 best-known pods comprised of 318 individuals, 152- 

229 of which were alive at any given time. All animals were not resighted in all years – in 

83% of instances animals were seen in consecutive years, in 14% there were gaps of 1-2 years 

in resightings, and in 3% there were gaps of 3-5 years. As a result, the exact year of death 

may not have been known in a few cases, and we amortized these over the period in question. 

Although newly recruited calves were not always seen in the year they were born, the year of 

birth could usually be established based on their size when first seen. To account for viable 

calves that might have been born during gaps but died prior to being seen, we applied a small 

correction (1.2 calves out of 141 observed births) based on the survival rates of calves that 

were observed every year and the number and length of gaps between consecutive encounters 

with reproductive females. The population included AB-pod, which was observed swimming 

in oil following the Exxon Valdez oil spill in 1989 and suffered very high mortality in that and 

the following year. We excluded AB-pod in development of the baseline population model, 

and utilized the model to assess its dynamics during and following the oil spill. 

Following the approach developed by Olesiuk, Bigg and Ellis (1990) and updated by 

Olesiuk, Ellis, Ford and Balcomb (2000) for BC and WA resident killer whales, and using 

genealogies developed for southern Alaskan killer whales (Matkin, Ellis, Olesiuk and Saulitis 

1999; Matkin, Ellis, Saulitis, Barrett-Lennard and Matkin 1999) we employed various 

methods were used to estimate the ages of animals. A total of 178 whales were born during or 

just prior to the start of the study, and the exact year of birth could be established based on 

their small size in the year they were first observed. We refer to these as known-aged 

animals. Another 12 animals were smaller juveniles when first seen, and only the 

approximate year of birth could be determined by their size. The error associated with these 

estimates was judged to range from ±1 years for the youngest to ±5 years for the oldest 

juveniles. The 29 females that were juvenile-sized when first seen (but too large to accurately 

age based on size) were aged in reference to the year in which they gave birth to their first 

viable calf. The mean age at first birth was determined from known-aged animals. However, 

since the known-aged animals in AK study were too young to fully represent the maturation 

curve, we adopted the maturation curve for BC-WA residents, which indicated that the first 

viable calf was born at a mean age of 15.4 years (range 10-21 years). The uncertainty 

associated with these age estimates is about ±5 years, the observed range in age at which 

females first give birth. The 49 females that were adult-sized and first seen and gave birth to 

their first known viable calf during or prior to the study, were also aged in reference to the 

year of birth of their first viable calf. Since these adult-sized females may actually have given 

birth and lost younger progeny prior to the study, we applied a correction to account for 

potential calf loss based on calving intervals and survival rates of calves (see Olesiuk, Bigg 

and Ellis 1990). The corrections ranged from 0.6 years for females giving birth to their first 



117

known offspring early in the study, to 1.9 years for females whose oldest offspring was aged 

15 years at the beginning of the study, to 5.1 years for females whose oldest offspring was 

aged 30 years at the start of the study. The 25 males that were juvenile-sized when first seen 

(but too large to estimate accurately based on size) were aged in reference to the year they 

attained sexual maturity. Age at sexual maturity was determined based on the year the dorsal 

fin first attained a height-to-width ratio of 1.4. For the same reasons outlined above for 

females, the maturation curve for northern BC resident males was employed, which indicated 

that males typically reached maturity at a mean age of 14.2 years (range 10-18 years). The 

uncertainty for these ages was thus about ±4 years. The 8 males that were sexually but not 

physically mature were aged in reference to the year the fin was completely developed. Data 

form BC-WA indicated that completion of fin development typically required 5.4 years (range 

3-7 years), which thus added an additional ±2 years to the uncertainty in the age estimate. For 

the 19 oldest males that were physically mature when first seen, we could only estimate their 

minimum age by assuming they had attained physical maturity in the year they were first 

seen. 

Thus far the rate of maturation for females in the Alaska population seems consistent 

with the maturation curve for BC-WA, which suggests that females typically give birth to 

their first viable calf at about age 15 years of age. Calves were subsequently produced at 

intervals that usually ranged from 3-7 years (mean 4.9 years), but were occasionally as short 

as 2 years or as long as 12 years. Mean calving intervals increased slightly but significantly 

with age of the mother, from 4.3 years at age 15 to about 5.6 years by age 40. Fecundity rates 

declined much more sharply with age, mainly because older females stopped calving. We 

estimated the rate of onset of post reproduction from the ratio of fecundity of reproductivelyactive 

females (defined as those that had given birth within the last 10 years) to all females. 

The median age of onset of reproductive senescence was 45 years, with virtually all female 

being post-reproductive by age 55 years. Southern Alaska resident killer whales would be 

expected to produce 5.7 calves over a 30-year reproductive lifespan, which was slightly 

greater than the 4.3 calves produced over a 23-year reproductive lifespan for BC northern 

residents. 

Survivorship for both males and females conformed with the classic mammalian Ushaped 

curve, indicating that the youngest and oldest animals experienced the highest 

mortality; however, the curve was narrower for males than females. Mortality rates for 

juveniles could not be estimated separately for each sex, but virtual equal numbers of males 

and females matured during the study suggesting that rates were similar (assuming an equal 

sex ratio at birth). The survivorship curve for males was very similar to those observed in 

northern BC residents, but the curve for females was narrower indicating that mortality 

increased more rapidly following the onset of reproductive senescence. 

The life history parameters were incorporated into life tables and a Lesile-type matrix 

population model to determine population parameters and model its dynamics. The life tables 

indicated that females had a mean life expectancy of 39 years and maximum longevity of 

roughly 60-70 years, and (assuming mortality of oldest males was the same as BC northern 

residents) males a mean life expectancy of 31 years and maximum longevity of roughly 50-60 

years. The reproductive value of females (i.e. the expected subsequent calf production) 

increased from 4.0 calves at birth to 4.4 calves at age 15 (because not all juveniles survive to 

reproduce), and then declined to zero by age 55 as they reached the end of their reproductive 

lifespan. 



118

The population model predicted that the population should increase at 2.7% per annum 

and be comprised of 51% juveniles, 23% mature males, 22% reproductive females and 5% 

post-reproductive females. The population actually grew at 3.3% per annum, and was 

comprised of 51% juveniles, 19% mature males, 24% reproductive females, and 7% postreproductive 

females. The population biology of Alaskan killer whales was remarkably 

similar to that observed in B.C. and Washington State during the 1970s and 80s, which 

increased at 2.9% and was comprised of 50% juveniles, 19% mature males, 21% reproductive 

females, and 10% post-reproductive females. One notable difference was that females in 

Alaska appeared to experience a more abrupt increase in mortality as they approached 

reproductive senescence, resulting in reduced longevity. During the Alaskan study, however, 

the proportion of post-reproductive females declined from 11% to 5%, suggesting it 

represented a period of atypically high morality for older females, and as a result we may 

have underestimated average female life expectancy and longevity. 

The population model was used to assess the dynamics of AB-pod, and the impact of 

the Exxon Valdez spill. This pod declined from 36 individuals in 1988 to 22 by 1990, which 

was nearly 10 times the expected mortality rate. Although other pods have increased at a 

mean rate of 3.3% per annum in the decade following the spill, AB-pod has shown little 

growth. Nevertheless, the population model indicated that the number of births in AB-pod 

since 1990 has been close to the number expected based on its sex- and age-structure (14 

observed births versus 13 predicted), although the number of deaths has been somewhat 

greater than expected (10 observed versus 6 expected). Thus, a reduced birth rate or greatly 

elevated death rate does not explain the lack of recovery of AB-pod. However, the 

reproductive value of the pod declined disproportionately to its reduction in size (49% versus 

38% respectively), implying that the animals lost following the spill tended to be those with 

higher than average reproductive values, i.e. young females. Had these females not been lost, 

the model indicated that an additional 12 calves would have been recruited into the pod in the 

decade following the spill. It thus appears the lack of recruitment due to the loss of females 

with high reproductive value is the primary reason for the lack of recovery of AB-pod 

following the Exxon Valdez oil spill. 

References: 

Olesiuk, P. F, M. A. Bigg, and G. M. Ellis. 1990. Life history and population dynamics of 

resident killer whales (Orcinus orca) in coastal waters of British Columbia and 

Washington State. Rep. Int. Whal. Commn. (Special Report 12): 209-243. 

Olesiuk, P. F., G. M. Ellis, J. K. B. Ford and K. C. Balcomb. 2000. An update on the 

population dynamics of southern and northern resident whales in B.C. and Washington 

State. Presentation at the Southern Resident Killer Whale Workshop, National Marine 

Mammal Laboratory, Seattle, WA, 1-2 April 2000. 

Matkin, C. O., G. M. Ellis, P. Olesiuk, and E. L. Saulitis. 1999. Association patterns and 

inferred genealogies of resident killer whales, Orcinus orca, in Prince William Sound, 

Alaska. Fishery Bulletin 97(4): 900-919. 

Matkin, C. O., G. M. Ellis, E. L. Saulitis, L. G. Barrett-Lennard, and D. R. Matkin. 1999. 

Killer whales of southern Alaska. North Gulf Oceanic Society, Homer, Alaska. 96 pp. 



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MONITORING WHALE WATCHING ACTIVITY IN INTERNATIONAL WATERS 

Pakenham M. 

Fisheries and Oceans 25 Huron St. Victoria, B.C. Canada V8V 4V9, Pakenhamm@pac.dfo-mpo.gc.ca 

The waters of Canada’s Pacific coast provide habitat for an extraordinary abundance and 

diversity of marine mammals and seabirds. The Committee on the Status of Endangered Wildlife in 

Canada (COSEWIC) in November 2001, listed the southern resident population of north-eastern 

Pacific orcas as “Endangered”. The seemingly endless opportunities to encounter marine 

wildlife around southern British Columbia and Washington state have given rise to 

tremendous growth in commercial and recreational whale watching activities; estimated at 

USD$68 million annually in British Columbia alone. This economic growth has increased the 

pressure on the resident orca population dramatically. To raise awareness and help reduce 

potentially harmful impacts from these threats, the Marine Mammal Monitoring Project (M3) 

has collaborated with several Canadian and US agencies to develop international guidelines 

for marine mammal viewing. The M3 stewardship patrol vessel provides an on-water 

presence around whale watching activities and allows crew members to record observations 

on vessels engaged in wildlife viewing. Compiled into a database, this information provides 

the basis for feedback reporting to industry, and allows for the accurate characterisation of 

marine mammal viewing activities to assist resource managers and key-decision-makers. In a 

dynamic environment with up to fifty vessels actively viewing as many as seventy-eight 

orcas, the challenges for accurate observation have lead to new and innovative techniques for 

monitoring. As Canada and the U.S. move towards the development of marine mammal 

viewing regulations, issues such as jurisdiction, human behaviour change, licensing of 

vessels, intensity of activity, acoustical implications, sanctuaries, bio-accumulation of toxics, 

recovery plans and enforcement are ahead. 



120

LIFE HISTORY AND DECLINE OF KILLER WHALES IN CROZET 

Introduction 

ARCHIPELAGO, SOUTHERN INDIAN OCEAN 

Poncelet E. 1,2 , Guinet C. 1 , Mangin S. 1 , Barbraud C. 1 . 

1 Centre d’Etudes Biologiques de Chizé, 79360 Villiers-en-Bois, France, 

2 1, allée des Oliviers, 06400 Cannes, France, eponcelet@ifrance.com 

Killer whales in the coastal waters of Possession Island, Crozet Archipelago, southern 

Indian Ocean, are the subject of a long term monitoring study which started in 1987, 

additional opportunistic pictures back to the sixties and seventies were also analysed (Guinet, 

1988). Latest population parameters were presented by Guinet in 1991. For the period 1987- 

1990, 76 individuals were identified and the population declined by 7%. Since 1991, 

additional photo-identification pictures were collected through dedicated field work but also 

opportunistically. In the present study, we analysed the whole data set available to estimate 

population parameters and trends with mark-recapture models. 

Methods 

With regard to killer whales’ occurrence pattern in the coastal waters of Possession 

Island, mainly in October-December and in some extent in January (Guinet, 1991), we 

worked with shifted years running from April to March to include this peak in a single year 

(e.g., year 1998 started in April 1998 and ended in March 1999). 


The photo-identification field work was conducted from several locations on the shore 

of Possession Island, one of the main island of Crozet Archipelago. Sighting histories were 

extracted from the photo-identification database i) to apply mark-recapture models and ii) to 

calculate gross fecundity rates. 

Mark-recapture modelling 

We considered sets of near years (consecutive when possible) with high photoidentification 

effort, and eventually high number of new identifications, to estimate a trend in 

abundance with Robust Design mark-recapture models. The program CAPTURE (Rexstad and 

Burnham, 1991) was used to handle different models featuring an individual heterogeneity in 

the recapture probability (h) and/or a behavioural response to capture (b) and/or a timedependent 

recapture probability (t), or none of the previous (M(0)). 

Years with low photo-identification effort (less than 15 pictures) were discarded to estimate 

survival without excessive bias. The program U-CARE (Choquet et al., 2001) was used to test 

the goodness-of-fit of the general Cormack-Jolly-Seber (CJS) model to our data, and CJSderived 

models were handled with the program MARK (White and Burnham, 1999). 

Gross fecundity calculation 

The average annual fecundity rate was calculated after the method used by Bigg in 1982. 

It was defined as the proportion of the summed number of years for which identified mature 



121

females were monitored (the “cow years”), against the number of viable neonates (about 12 

months of age) born to these females during the cow years. 

Results 


The photo-identification effort was highly variable, ranging from 1 to 783 pictures/year 

(fig. 1). Years with high effort correspond to years when dedicated field work has been carried 

out. In 2001, the cumulated number of identified individuals was 93, including animals 

assumed dead. An undetermined number of individuals were not identified because they were 

poorly marked and did not show up close enough to the shore to get good identification 

pictures. 

Abundance modelling and estimation 

We selected the years 1988, 1989, 1998 and 2000 as two sets of near years representing 

two primary recapture occasions with a 9-year interval, each including two secondary 

recapture occasions. After these data, the program CAPTURE provided a selection criteria for 

each model available (table 1) 

Cumulated number of identified inviduals 

100 

90 

80 

70 

60 

50 

40 

30 

20 

5 1 5 9 1 2 3 7 27 10 

0 

11 6 

44 

61 

4 4 

40 40 

1964 

1965 

1966 

1967 

Effort (number of pictures) 

Cumulated number of identified individuals 

1968 

1969 

1970 

1971 

1972 

1973 

1974 

1975 

1976 

1977 

1978 

1979 

1980 

1981 

1982 

Years 

1983 

1984 

1985 

1986 

445 

1987 

397 

330 

1988 

1989 

72 

1990 

1991 

1992 

1993 

1 1 1 13 

Fig. 1. Photo-identification effort (number of pictures) and cumulated number of 

identified individuals from 1964 to 2001. 

Table 1. Model selection criteria computed by the program CAPTURE. The higher the 

value is, the better the model fits the data. 

M(0) M(h) M(b) M(bh 

) 

1994 

1995 

1996 

395 

1997 

1998 

83 

783 

1999 

2000 

7 

2001 

1000 

900 

800 

700 

600 

500 

400 

300 

200 

100 

M(t) M(th) M(tb) M(tb 

h) 

0.84 0.16 0 0.85 0.41 0.18 0.09 1 

The first highest ranked model is M(tbh) and has no estimator. The second highest 

ranked model is M(bh) for which the program CAPTURE proposes two estimators: Pollock 



0 

Effort (number of picutres) 

122

and Otto’s and Generalised Removal. Pollock and Otto’s estimator provided estimates of 93 

(SE = 6.78, approximate 95% CI = 84-110) individuals in 1988-1989 and 43 (SE = 4.47, 

approximate 95% CI = 38-56) in 1998-2000 (fig. 2). The Generalised Removal estimator 

couldn’t estimate the abundances by lack of sufficient recapture occasions. Finally the third 

highest ranked model, M(0), provided estimates of 83 (SE = 6.22, approximate 95% CI = 76- 

101) individuals in 1988-1989, and 36 individuals (SE = 2.58, approximate 95% CI = 34-46, 

fig.2) in 1998-2000. 

Survival modelling and estimation 

The years considered for survival modelling were 1977, 1980, 1982, 1985 to 1989, 1990 

and 1998 to 2000. The goodness of fit tests indicated that there was no departure from the 

general CJS model. However, the model did not fit the data very well (χ²=47.40, df=27, 

p=0.009). The overdispersion factor ( ĉ ) measuring the lack of fit as the ratio of the degrees of 

freedom against the χ² statistic was 1.755. It is commonly admitted that a c ˆ inferior to 3 is 

acceptable and can be used in the model selection (Lebreton et al., 1992). 

Abundance estimates 

(with 95% CI) 

120 

100 

80 

60 

40 

20 

0 

M(bh) model 

M(0) model 

1988-1989 1998-2000 

Periods 

Fig. 2. Outputs of the Robust Designs models M(bh) and M(0) for the years1988, 1989, 

1998 and 2000. 

The process of model selection is illustrated in table 2. Our initial model was the general 

CJS model (1), which features time-dependent survival (φ) and recapture probabilities (p). In a 

first step, we simplified the survival modelling. A model with constant survival fitted the data 

better than the initial model (model 1 vs. 2), but a model with trend-dependent survival was 

even more acceptable (model 1 vs. 3). In a second step, we simplified the modelling of the 

recapture probability. A model with a constant recapture probability did not fit the data better 

than the initial model (model 1 vs. 4), but a model with a photo-identification effort-dependent 

recapture probability fitted better (model 1 vs. 5). Finally, in a third step, we simplified both 

survival and recapture probability and tested a model with a trend-dependent survival and an 

effort-dependent recapture probability. This model was more acceptable than the initial model 

(model 1 vs. 6). 



123

Table 2. Process of model selection for the analysis of survival (models are adjusted for 

ĉ = 1.755). QAICc is the corrected Akaike’s Information Criterion: the lower the QAICc is, 

the more parsimonious the model is. 

Model QAICc ∆QAICc #Param. 

(3) φtrend,pt 280.479 0.000 12 

(2) φ,pt 287.295 6.816 12 

(5) φt,peffort 289.086 8.607 7 

(6) φtrend,peffort 291.908 11.429 4 

(1) φt,pt 299.199 18.720 22 

(4) φt,p 311.271 30.792 12 

The most parsimonious model was model 3 featuring a time trend-dependent survival 

and a time-dependent recapture probability, and estimating a declining survival from 0.979 

(SE = 0.016, 95% CI = 0.907-0.995) in 1977-1980 to 0.815 (SE = 0.048, 95% CI = 0.701- 

0.892) in 1999-2000 (fig. 3). 

Average fecundity rate 

From 1985 to 1990, only two viable neonates were identified in 42 cow years, resulting 

in a average annual fecundity rate of 4.76%. From 1998 to 2000, no viable neonate was 

observed, resulting in a null fecundity. 

Survival rate (with 95% CI) 

1 

0.95 

0.9 

0.85 

0.8 

0.75 

0.7 

0.65 

Periods 

Fig 3. Output of the φtrend,pt model: annual survival rates for all individuals between 

1977 and 2000 (confidence intervals corrected for ĉ = 1.755). 

Discussion 

The modelling of the abundance and survival of the killer whales in the coastal waters of 

Possession Island indicate strong declines between 1988 and 2000. Several factors may have 

combined and resulted in this situation: i) a low and decreasing fecundity, possibly impacted 

by a density dependence (Allee effect); ii) the decline of the main preys: large baleen whales 

due to past whaling, and southern elephant seals (Mirounga leonina) from the 1970 to 1990 

which remained in low numbers up to 1997 at least (Guinet et al., 1999); iii) the possible 

mortality induced by recent interactions with the Patagonian toothfish (Dissostichus 

eleginoides) longline fishery; and iv) the possible dispersion of individuals or groups from the 

coastal waters. A few individuals were observed with poorly known “offshore” killer whales 

interacting with longliners, but presently, there is no evidence of mixing with surrounding 



124

killer whale concentrations in Prince Edward Islands, south Africa or Antarctic. A preliminary 

toxicological study indicates that PCBs levels are considerably lower than in British Columbia 

transients, however the burdens are not negligible (Ross, pers. com.) and the effects of PCBs 

on health at the observed concentrations are unknown. We fear that the killer whales of 

Possession Island might disappear with unique genetic diversity and social culture, like AT1 

transients in Alaska (Matkin et al., 1999). 

References 

Bigg, M.A. 1982. An assessment of killer whale (Orcinus orca) stocks off Vancouver Island, 

British Columbia. Reports of the International Whaling Commission, 32: 655-666. 

Guinet, C. 1988. Historique de la présence des orques autour de l'île de la Possession, archipel 

Crozet: photo-identification 1964-1986. Mammalia, 52(2): 285-289 

Guinet, C. 1991. L'orque (Orcinus orca) autour de l'Archipel Crozet, comparaison avec d'autres 

localités. Revue d'Ecologie (Terre et Vie), 46: 18-34. 

Guinet, C., Jouventin, P., Weimerskirch, H. 1999. Recent population change of the southern 

elephant seal at Îles Crozet and Îles Kerguelen: the end of the decrease? Antarctic Science, 

11(2): 193-197. 

Lebreton, J.-D., Burnham, K.P., Colbert J., Anderson D.R. 1992. Modeling survival and testing 

biological hypotheses using marked animals: a unified approach with case studies. Ecological 

Monographs, 62(1): 67-118. 

Matkin, C.O., Saulitis, E.L., Ellis, G.M., Barrett-Lennard, L.G. 1999. The AT1 group of 

transient killer whales in southern Alaska: a unique population in decline. In: Abstracts of 13 th 

Biennial Conference on the Biology of Marine Mammals, Maui, Hawaii, USA, 28 November - 

3 December 1999. The Society for Marine Mammalogy. 

Rexstad, E., Burnham, K.P. 1991. Users’ guide for Interactive Program CAPTURE. Colorado 

Cooperative Fish & Wildlife Research Unit, Colorado State University, Fort Collins, 

Colorado. 



125

TOXIC CHEMICAL POLLUTION AND PACIFIC KILLER WHALES (ORCINUS 

ORCA) 

Peter S. Ross 1 , Graeme Ellis 2 , John K.B. Ford 2 , Lance-Barrett-Lennard 3 

1 Institute of Ocean Sciences, P.O. Box 6000, Sidney BC V8L 4B2, Canada (rosspe@pac.dfompo.gc.ca) 

2 Pacific Biological Station, Hammond Bay Road, Nanaimo BC Canada 

3 Vancouver Aquarium, P.O. Box 3232, Vancouver BC V6B 3X8 Canada 

ABSTRACT 

We recently found that killer whale (Orcinus orca) populations frequenting the coastal 

waters of British Columbia (Canada) and Washington (USA) are among the most 

contaminated marine mammals in the world. Our study benefited from (i) knowledge of 

individual identities, relationships and feeding preferences for all resident and most transient 

killer whales (documented through a long-term photo-identification catalogue); (ii) a biopsy 

dart system which sampled skin and blubber (approximately 250 mg); and (iii) comprehensive 

chemical analysis, which detected over 200 different Persistent Organic Pollutants (POPs), 

including polychlorinated biphenyls (PCBs). We are currently attempting to answer two 

major questions; namely: ‘Where are these contaminants coming from?’ and ‘Are these high 

contaminant levels affecting the health of killer whales?’. To this end, we are carrying out a 

food chain-based study to track the movement and fate of contaminants in coastal British 

Columbia and the NE Pacific Ocean. We are also developing a suite of skin- and blubberbased 

biomarkers of contaminant effects. Our harbour seal (Phoca vitulina) research has 

contributed to an understanding of chemical sources, contaminant trends in the region and 

POP-related health effects in marine mammals. Our work suggests that while Puget Sound 

(Washington State) represents a PCB “hotspot”, the preferred prey of resident killer whales 

(Chinook salmon) accumulates 99% of its POP burden from the open Pacific Ocean. While 

contaminated sites along the west coast of North America may continue to introduce 

chemicals into killer whale food chain, the deposition of atmospherically-transported 

chemicals of Asian origin into the NE Pacific represents an additional concern. The 20% 

decline in southern resident killer whale numbers in recent years highlights the need for 

conservation-based management which addresses such findings in the context of diminishing 

prey abundance and disturbance from heavy boat traffic. 

INTRODUCTION 

Killer whales (Orcinus orca) represent, without question, charismatic megafauna, 

attracting the interest and attention of millions of people worldwide. British Columbia is no 

exception, where aboriginal legends and new world ecotourism have cemented the status of 

killer whales as the principal icons of the NE Pacific Ocean. In addition to the public interest 

in killer whales, there has been considerable scientific research on this marine mammal 

species in British Columbia (B.C.). The pioneering work of the late Dr. Michael Bigg and his 

colleagues in establishing individual-based photo-identification catalogues (Bigg et al. 

1990;Ford et al. 2000;Ford and Ellis 1999;Ford et al. 1994) has provided an invaluable basis 

for studies of killer whale population abundance, distribution, feeding ecology, 

communication, and genetic relationships (Ford et al. 1998;Barrett-Lennard 2000;Ford and 

Fisher 1982). 



126

TOXICOLOGICAL EFFECTS OF TOXIC CHEMICALS IN MARINE 

MAMMALS 

There are several classes of environmental contaminants of concern in the context of 

marine mammals. In general, the persistent (P), bioaccumulative (B) and toxic (T) or PBT 

chemicals represent the greatest health risk to high trophic level marine mammals. This is due 

to the fact that such chemicals do not readily break down in the environment or in organisms; 

they are lipophilic (fat-soluble) and therefore become increasingly concentrated at each level 

in aquatic food chains as fats are metabolized; and are hormone mimics. Such “endocrine 

disrupting” compounds can present a health risk to highly exposed wildlife. 

Chemicals of particular concern on a global scale include the “legacy” (i.e. regulated in 

the industrialized world) compounds such as the polychlorinated biphenyls (PCBs), the 

polychlorinated dibenzo-p-dioxins (PCDDs or dioxins), and the organochlorine pesticide 

DDT. Current or “new” chemicals of concern (i.e. largely unregulated in the industrialized 

world) include the polybrominated diphenyl ethers (PBDEs) and pharmaceutical products. 

The endocrine disrupting properties of many members of these chemical classes 

represent a profound concern to marine mammals. Several populations of pinnipeds and 

cetaceans inhabiting or frequenting the industrial waters of northern Europe, the 

Mediterranean Sea, the St Lawrence estuary in eastern Canada, and Puget Sound in NW 

U.S.A. have been found to be highly contaminated with industrial and agricultural chemicals 

such as PCBs and DDT (Ross et al. 1996a; Aguilar and Borrell 1994; Muir et al. 1999; Ross 

et al. 2001). High contaminant levels have been associated with reproductive impairment and 

skeletal lesions in free-ranging marine mammals (Helle et al. 1976; Bergman et al. 1992). 

Captive feeding studies have implicated PCBs in reproductive, immune function and 

endocrine effects in harbour seals (Reijnders 1986; De Swart et al. 1996; Ross et al. 1996a; 

Ross et al. 1996b). 

CONTAMINANTS IN KILLER WHALES 

Two major factors explain the relative contamination of many marine mammals: i) 

trophic level (the higher trophic level species being more contaminated because of 

biomagnification through the food chain); and ii) proximity to industrial areas. Fish-eating or 

mammal-eating marine mammals are therefore almost always more contaminated with PBT 

contaminants than baleen whales. Despite findings that marine mammals frequenting 

industrial coastal waters have a tendency to be contaminated with e.g. PCBs, it has become 

increasingly evident that marine mammal inhabiting even remote (“pristine”) environments 

have become contaminated as a result of long-range transport of atmospheric pollutants (Muir 

et al. 2000). 

More recently, the photo-identification catalogues have served as a foundation for 

studies of toxic chemicals in killer whales (Ross et al. 2000). The development of a biopsy 

technique to obtain micro-samples of skin and underlying blubber from known killer whales 

at a distance (Barrett-Lennard et al. 1996) enabled an assessment of the effects of such factors 

as age, sex and dietary preferences on contaminant concentrations. The inherent value and 

ultimate impact of our contaminant studies in killer whales reflects a combination of i) 

knowledge of age, sex and diet of sampled individuals, ii) the ability to obtain microsamples 

in a minimally-invasive manner, iii) a highly sensitive method to measure contaminants in 

samples obtained, and iv) our ability to set the results in the context of biological, ecological 



127

and toxicological sciences. Our findings can therefore provide us with a robust overview of 

the degree of toxic chemical contamination in healthy, free-ranging Pacific killer whales. 

Our recent research indicated that the transient and southern resident killer whale 

communities of the NE Pacific Ocean can now be considered among the most contaminated 

marine mammals in the world, surpassing the endangered St Lawrence Beluga whales by a 

factor of two to five times (Ross et al. 2000). Concentrations of PCBs in all killer whale 

populations studied in British Columbia exceeded immunotoxicity and endocrine disruption 

threshold levels established for captive harbour seals (Ross et al. 1995; De Swart et al. 1994). 

While interspecies comparison must be made with caution, the free-ranging killer whales in 

the NE Pacific Ocean must be considered at risk for adverse health effects. 

WHERE ARE THESE CONTAMINANTS COMING FROM? 

Upon discovering that NE Pacific killer whales can now be considered among the most 

contaminated marine mammals in the world, we asked ourselves ‘where are these chemicals 

coming from?’. We are exploring this question in different ways. Firstly, our harbour seal 

research suggests that Puget Sound (northern Washington State) represents a ‘hotspot’ for 

PCB contamination (Ross et al. 2001). This suggests that local (i.e. resident) fish species (and 

occasional prey items for resident killer whales) are highly contaminated with PCBs. In 

addition, the principal prey for resident killer whales (salmonids) are likely obtaining most of 

their contaminants in offshore areas where they grow and feed in the North Pacific Ocean 

(O'Neill et al. 1998; Ewald et al. 1998). This suggests that resident killer whales are, in fact, 

providing a signature of both “local” and “global” contamination. 

As long-lived, high trophic level species, killer whales are vulnerable to contamination 

by persistent and bioaccumulative contaminants. While the “legacy” chemicals have been 

regulated in North America and Europe, many are still in production and use in the 

developing world. In addition, “new” chemicals have been found at increasing concentrations 

in arctic ringed seals (Ikonomou et al. 2002), suggesting that the global environment 

continues to be contaminated by PBT compounds. Levels of most “legacy” contaminant 

decreased steadily during the 1970s and 1980s, although these trends have since stalled 

(Addison and Stobo 2001). Killer whales will continue to face risks from exposure to many of 

these compounds. Our current assessment using a modelling-based approach to predicting 

concentrations in killer whales over time (Hickie et al. 2001) suggests that these risks are 

likely to continue for decades to come. 

REFERENCES 

1. Addison,R.F. and Stobo,W.T. 2001. Trends in organochlorine residue concentrations 

and burdens in grey seals (Halichoerus grypus) from Sable Is., N.S., Canada, between 

1974 and 1994. Environ.Pollut. 112(3): 505-513. 

2. Aguilar,A. and Borrell,A. 1994. Abnormally high polychlorinated biphenyl levels in 

striped dolphins (Stenella coeruleoalba) affected by the 1990-1992 Mediterranean 

epizootic. Sci.Total Environ. 154: 237-247. 



128

3. Barrett-Lennard,L.G. 2000. Population structure and mating patterns of killer whales 

(Orcinus orca) as revealed by DNA analysis. University of British Columbia, Ph.D. 

thesis. 

4. Barrett-Lennard,L.G., Smith,T.G., and Ellis,G.M. 1996. A cetacean biopsy system 

using lightweight pneumatic darts, and its effect on the behavior of killer whales. 

Mar.Mammal Sci. 12: 14-27. 

5. Bergman,A., Olsson,M., and Reiland,S. 1992. Skull-bone lesions in the Baltic grey 

seal (Halichoerus grypus). Ambio 21: 517-519. 

6. Bigg,M.A., Olesiuk,P.F., Ellis,G.M., Ford,J.K.B., and Balcomb,K.C. 1990. Social 

organization and geneology of resident killer whales (Orcinus orca) in the coastal 

waters of British Columbia and Washington State. Rep.Int.Whaling Comm. 12: 383- 

405. 

7. De Swart,R.L., Ross,P.S., Vedder,L.J., Timmerman,H.H., Heisterkamp,S.H., Van 

Loveren,H., Vos,J.G., Reijnders,P.J.H., and Osterhaus,A.D.M.E. 1994. Impairment of 

immune function in harbor seals (Phoca vitulina) feeding on fish from polluted waters. 

Ambio 23: 155-159. 

8. De Swart,R.L., Ross,P.S., Vos,J.G., and Osterhaus,A.D.M.E. 1996. Impaired 

immunity in harbour seals (Phoca vitulina) exposed to bioaccumulated environmental 

contaminants: review of a long-term study. Environ.Health Perspect. 104 (suppl. 4): 

823-828. 

9. Ewald,G., Larsson,P., Linge,H., Okla,L., and Szarzi,N. 1998. Biotransport of organic 

pollutants to an inland Alaska lake by migrating sockeye salmon (Oncorhyncus 

nerka). Arctic 51: 40-47. 

10. Ford,J.K.B. and Ellis,G.M. 1999. Transients: Mammal-hunting killer whales. UBC 

Press, Vancouver. 

11. Ford,J.K.B., Ellis,G.M., and Balcomb,K.C. 1994. Killer whales. UBC Press, 

Vancouver. 

12. Ford,J.K.B., Ellis,G.M., and Balcomb,K.C. 2000. Killer whales. UBC Press, 

Vancouver. 

13. Ford,J.K.B., Ellis,G.M., Barrett-Lennard,L.G., Morton,A.B., Palm,R.S., and 

Balcomb,K.C. 1998. Dietary specialization in two sympatric populations of killer 

whales (Orcinus orca) in coastal British Columbia and adjacent waters. Can.J.Zool. 

76: 1456-1471. 

14. Ford,J.K.B. and Fisher,H.D. 1982. Killer whale (Orcinus orca) dialects as an indicator 

of stocks in British Columbia. Rep.Int.Whaling Comm. 32: 671-679. 

15. Helle,E., Olsson,M., and Jensen,S. 1976. DDT and PCB levels and reproduction in 

ringed seal from the Bothnian Bay. Ambio 5: 188-189. 



129

16. Hickie, B. D., Ross, P. S., and Macdonald, R. An examination of the history of PCB 

accumulation by north Pacific killer whales. Society for Marine Mammalogy 

Vancouver, Canada. 2001. 

17. Ikonomou,M.G., Rayne,S., and Addison,R.F. 2002. Exponential increases of the 

brominated flame retardants, polybrominated diphenyl ethers, in the Canadian Arctic 

from 1981 to 2000. Environmental Science and Technology 36: 1886-1892. 

18. Muir,D., Riget,F., Cleemann,M., Skaare,J., Kleivane,L., Nakata,H., Dietz,R., 

Severinsen,T., and Tanabe,S. 2000. Circumpolar trends of PCBs and organochlorine 

pesticides in the Arctic marine envrionment inffered from levels in ringed seals. 

Environmental Science and Technology 34: 2431-2438. 

19. Muir,D.C.G., Koczanski,K., Rosenberg,B., and Béland,P. 1999. Persistent 

organochlorines in beluga whales (Delphinapterus leucas) from the St Lawrence river 

estuary-II. Temporal trends, 1982-1994. Environ.Pollut. 93(2): 235-245. 

20. O'Neill,S.M., West,J.E., and Hoeman,J.C. 1998. Spatial trends in the concentration of 

polychlorinated biphenyls (PCBs) in Chinook (Oncorhyncus tshawytscha) and Coho 

salmon (O. kisutch) in Puget Sound and factors affecting PCB accumulation: Results 

from the Puget Sound Ambient Monitoring Program. Puget Sound Research '98 312- 

328. 

21. Reijnders,P.J.H. 1986. Reproductive failure in common seals feeding on fish from 

polluted coastal waters. Nature 324: 456-457. 

22. Ross,P.S., De Swart,R.L., Addison,R.F., Van Loveren,H., Vos,J.G., and 

Osterhaus,A.D.M.E. 1996a. Contaminant-induced immunotoxicity in harbour seals: 

wildlife at risk? Toxicology 112: 157-169. 

23. Ross,P.S., De Swart,R.L., Reijnders,P.J.H., Van Loveren,H., Vos,J.G., and 

Osterhaus,A.D.M.E. 1995. Contaminant-related suppression of delayed-type 

hypersensitivity and antibody responses in harbor seals fed herring from the Baltic 

Sea. Environ.Health Perspect. 103: 162-167. 

24. Ross,P.S., De Swart,R.L., Van Loveren,H., Osterhaus,A.D.M.E., and Vos,J.G. 1996b. 

The immunotoxicity of environmental contaminants to marine wildlife: A review. 

Ann.Rev.Fish Dis. 6: 151-165. 

25. Ross,P.S., Ellis,G.M., Ikonomou,M.G., Barrett-Lennard,L.G., and Addison,R.F. 2000. 

High PCB concentrations in free-ranging Pacific killer whales, Orcinus orca: effects 

of age, sex and dietary preference. Mar.Pollut.Bull. 40: 504-515. 

26. Ross,P.S., Jeffries,S., Yunker,M., Addison, R.F., Ikonomou,M., and Calambokidis,J. 

2003: Harbour seals (Phoca vitulina) in British Columbia and Washington reveal both 

'local' and 'global' PCB, PDD and PCDF signals. submitted. 



130

THE BIOLOGY AND STATUS OF AN ENDANGERED TRANSIENT KILLER 

WHALE POPULATION IN PRINCE WILLIAM SOUND, ALASKA 

Eva Saulitis, Craig Matkin and Graeme Ellis 

North Gulf Oceanic Society, 60920 Mary Allen Ave., Homer, Alaska 99603, saulitis@pobox.xyz.net. 

The AT1 transient population of southern Alaska is on the verge of extinction. The 

AT1s are mammal-eating killer whales inhabiting a limited range, between Prince William 

Sound and the Kenai Fjords. They share this range with several resident (fish-eating) killer 

whale pods and with the Gulf of Alaska transient population; however, they do not associate 

with those groups. 

The AT1 killer whales are genetically isolated from both the west coast transient 

population that ranges from southeastern Alaska through southern California, from the 

sympatric Gulf of Alaska transient population, and from Prince William Sound residents 

(Barrett-Lennard 2000). The amount of genetic diversity within the AT1 genome suggests 

that these animals were recently part of a much larger population (Barrett-Lennard, pers. 

comm.) 

The AT1 diet consists primarily of harbor seals (Phoca vitulina) and Dall’s porpoises 

(Phocoenoides dalli). Unlike Gulf of Alaska transients, AT1 transients are not known to feed 

on western Steller sea lions (Eumetopias jubatus) (Saulitis et al. 2000). 

AT1 transients utilize three foraging strategies: nearshore foraging, offshore foraging 

and foraging in glacial fjords. Almost all prey killed during offshore foraging are porpoises. 

Porpoise attacks involve a coordinated effort of group members (mean size = 5.0 

whales/group) lasting up to 40 minutes. Nearshore and glacial fjord foraging are primarily for 

harbor seals. Group size for nearshore foraging was smaller than for offshore foraging (3.3 

killer whales/group.) Single males and male pairs were often observed hunting seals in 

glacial fjords, where seals congregate to give birth, molt and haul out. 

The acoustic repertoire of the AT1s mirrors their genetic separation from other 

transients. Their 12 stereotyped pulsed calls are entirely different than those of Gulf of 

Alaska or west coast transients. Use of calls by AT1 transients is context-specific and closely 

tied to their foraging strategies. Three calls are statistically correlated with foraging; these are 

low amplitude, short vocalizations easily masked by underwater background noise. 

Otherwise, foraging and traveling whales are silent, using a strategy of passive listening to 

locate prey. 

AT1 transients commonly travel in foraging groups of 2-6 that represent long-term 

associations among individuals, including male-male and female-offspring associations. 

Males commonly travel alone for periods of time, using specific stereotyped vocalizations to 

relocate other AT1s. These particular high amplitude calls are emitted almost exclusively for 

the purpose of long-distance communication and can be detected several km away. 

Regularly, larger groups of up to 22 AT1s form for social purposes. In these situations, 

whistles are the most common vocalization. High frequency whistles are considered close 

contact calls as they attenuate rapidly over distance. 

Since 1990, the AT1 transient population has declined from 22 animals to nine in 2002. 

This decline may reflect the interaction of several anthropogenic and biological factors. In 

1984, when the study began, the sex ratio of AT1s and their small population size already 

suggested a population in decline from a loss of reproductive females. Adult males made up 



131

41% of the population, double that of other transient populations and of resident pods. 

Nevertheless, between 1978 and 1984, the AT1s produced three viable offspring. Who were 

the fathers of those calves? Were they males who died in 1990, before biopsy work was 

begun? Or did females have access to other AT1-type individuals? Since 1984, no new AT1 

calves have been documented. 

The population of harbor seals, the AT1s’ primary prey, has declined by 80% since the 

1970s (Frost et al. 1999). The effect is more marked in the oil-impacted part of Prince 

William Sound. Nine AT1s disappeared during the winter of 1990, suggesting that those 

mortalities were oil spill related. Two AT1 males, one in his thirties, and one twenty-one 

year old who never physically matured, beached and died in 2000 and 2001. 

Analysis of blubber samples indicates that environmental toxin (PCB and DDT) levels 

in the blubber of AT1 transients are twenty to thirty times higher than those of residents, 

within the range known to cause reproductive problems in other marine mammal species 

(Ylitalo et al. 2001). 

As the apex predators in the marine food chain of Prince William Sound, the demise of 

the AT1 transient population points to persistent problems in the environment. The AT1s are 

symbolic of the fragility of ocean ecosystems. Their inevitable extinction will be a genetic 

loss, a further change in the ecological structure of Prince William Sound, and a cultural loss, 

as they are part of the traditional mythology of the region. Even today, Chugachmiut and 

Alutiiq Eskimo elders and tradition-bearers believe that when killer whales enter a bay, death 

will come to someone in their village, that whales are calling someone, as humans become 

killer whales when they die. Though there is little hope for the survival of the ATs, their fate 

illustrates the vulnerability inherent in the social structure of killer whale populations. 

REFERENCES CITED 

Barrett-Lennard, Lance. 2000. Population structure and mating patterns of killer 

whales, 

Orcinus orca, as revealed by DNA analysis. PhD dissertation, University of British 

Columbia, Vancouver, Canada. 

Frost, K.J, L.F. Lowry & J. Ver Hoef. 1999. Monitoring the trend of harbor seals in 

Prince William Sound after the Exxon Valdez oil spill. Marine Mammal Science: 15.2: 

494-506. 

Saulitis, E.L., C.O. Matkin, L. Barrett-Lennard, K. Heise & G. Ellis. 2000. Foraging 

strategies of sympatric killer whale (Orcinus orca) populations in Prince William Sound, 

Alaska. Marine Mammal Science: 16.1: 94-109. 

Ylitalo, G., C.O. Matkin, J. Buzitis, M.M. Krahn, L.L. Jones, T. Rowles & J.E. Stein. 

2001. Influence of life-history parameters on organochlorine concentrations in freeranging 

killer whales (Orcinus orca) from Prince William Sound, Alaska. The Science of the 

Total Environment: 281: 183-203. 



132

MATCHED VOCAL EXCHANGES OF SHARED STEREOTYPED CALLS IN FREE- 

RANGING RESIDENT KILLER WHALES 

Shapiro, A. D., Miller, P. J. O., Tyack, P. L., Solow, A. R.. 

Gatty Marine Laboratory; University of St. Andrews; Fife KY16 8LB; UK, as64@st-andrews.ac.uk. 

Previous recordings of resident killer whale groups reveal matrilineal group-specific call 

repertoires and a strong tendency for calls of the same type to be produced in series. Vocal 

interactions between individual free-ranging animals, however, had remained unexplored 

because it had not been possible to identify signalers reliably with a single hydrophone. Here 

we link acoustic arrivals of calls on a towed hydrophone array with visual tracking of photoidentified 

individuals to ascribe calls to a focal animal when separated by >35 m, and thereby 

out of visual range, from other members of its natal group. We confirm that individual 

members of a matrilineal natal group share a repertoire of stereotyped calls, and statistically 

examine aspects of call timing between group members. Because analysis of the intervals 

between stereotyped calls indicated that calls were produced in bouts with a bout criterion 

interval of 19.6s, we developed randomisation tests that preserved call interval structure. A 

rotation test revealed focal whales were four times more likely than chance to produce a call 

within 5 s of a call from a non-focal animal. Consecutive calls produced by different 

individuals during group calling bouts matched type more than expected by chance, providing 

further evidence that individual calling behaviour is influenced by the calling behaviour of 

group members. Matched exchanges of stereotyped calls may allow receivers to respond 

specifically to the signals of the previous signaler. By communicating individual position and 

possibly orientation, these exchanges may function to co-ordinate and synchronise movement 

patterns and group behaviour 



133

SATELLITE TRACKING STUDY OF MOVEMENTS AND DIVING BEHAVIOUR 

OF KILLER WHALES IN THE NORWEGIAN SEA 

Similä, Tiu (1), Holst, Jens Christian (2), Øien, Nils (3) and Hanson M. Bradley (4) 

1,2,3 Institute of Marine Research, P.O.Box 1870, Nordnes 5817 Bergen, Norway 

4 NOAA, Alaska Fisheries Science Center, National Marine Mammal Laboratory, 7600 Sand Point 

Way NE, Seattle, WA 98115 USA 

INTRODUCTION 

A long term photoidentification study on behavioural ecology of killer whales (Orcinus 

orca) was initiated in Norway in 1987. The occurrence of killer whales in coastal waters is 

related to the seasonal migrations of Norwegian spring-spawning herring (Clupea harengus) 

(Christensen 1988). This herring stock winters in a fjord system north of the arctic circle and 

an estimated 500-600 killer whales are present in this area from October to January (Similäet 

al. 1996). The behaviour and habitat use of killer whales has been studied in the wintering 

grounds of herring (Similä 1997) but the short period of daylight in fall and winter has not 

allowed for studies on possible diurnal patterns and group specific differences in area use and 

behaviour. After the killer whales and herring leave the wintering grounds, little is known 

about the movements or behaviour of killer whales (Similä et al. 1996). The lack of a core 

area for killer whale occurrence, especially during summer months, has made it difficult to 

locate killer whales between January and October. Recent developments in tag design has 

made it possible to study the ranging and diving behaviour of small odontocetes (for 

references see Hooker and Baird 2001). 

In 2000-2001 seven killer whales were equipped with satellite- and VHF tags in the 

wintering grounds of herring. The study was conducted in cooperation with studies on 

Norwegian spring-spawning herring, which is at least seasonally the main type of prey of 

killer whales in these waters. The aim of the project is to study seasonal movements and 

diving behaviour of killer whales, focusing on interactions between herring and killer whales. 

This abstract summarises preliminary results on range and habitat use of killer whales during 

wintering period of herring. 


Two whales were captured and tagged in 2000 and five whales in 2001. All whales were 

tagged in Vestfjord and Tysfjord in the core wintering grounds of herring in northern Norway. 

The transmitters deployed on the whales consisted of pair of tags mounted on the sides of the 

dorsal fin. A satellite transmitter was mounted on one side and VHF transmitter on the 

opposite side using a four pin attachment arrangement (Hanson 2001). Five of the satellite 

transmitters were were duty cycled to transmit daily while two of the tags transmitted every 3 

days. One of whales, an adult male, had a time-depth recorder attached with a suction cup 

providing 60 hours of detailed dive data after it floated free and was recovered. The 

performance of the five tags attached in 2001 was better than of the two tags attached in 2000. 

Based on observations made of one the tagged whales in 2000, the positions of the tag and 

its antenna, were modified which improved tag performance in 2001. All individuals were 

radio-tracked and observed after their release. No long-term reaction to the tags or tagging 

could be detected. 



134

The total number of good quality locations received from the tagged whales during the 

wintering period of herring varied between 12-56 positions. Most of the positions were 

received from the wintering grounds of herring. However, five of the tagged whales made 

long distance movements away from this area; the swimming and diving behaviour of the 

whales as well as information on prey items suggests that the function of these trips was to 

survey areas where herring is abundant during other seasons than winter. 

Based on photoidentification data collected since 1987 the range of killer whales during 

October-January had been estimated to be 13 583 km 2 (estimated as a minimum convex 

polygon). The satellite tracking study has expanded the known range of killer whales during 

this season considerably. The ranges varied between the individuals; the smallest estimated 

Kernel home range was 3566 km 2 (95 % isopleth) and the largest 288 284 km 2 (95 % 

isopleth). 

In addition to new knowledge about the range of the whales during this season, the data 

set has also given the first detailed insight into the habitat use of killer whale individuals 

within the wintering grounds of herring. There were differences in the habitat use of the pods 

and the core area where killer whales have been photoidentified was not used equally by the 

different groups. This data is currently being compared to the long-term photoidentification 

data set for analysis for the areas where the pods have been identified and for differences in 

the number of observations/pod. 

REFERENCES: 

Christensen, I. 1988. Distribution, movements and abundance of killer whales (Orcinus 

orca) in Norwegian coastal waters 1982-1987 based on questionnaire surveys. Rit Fiskideildar 

XI, 79-88. 

Hanson, M. B. 2001. An evaluation of the relationship between small cetacean tag 

design and attachment durations: a bioengineering approach. Unpubl. Ph.D. dissertation, 

Univ. of Washington, Seattle, WA. 208 pp. 

Hooker, S and Baird, R. 2001. Diving and ranging behaviour of odontocetes: a 

methodological review and critique. Mammal Rev 31 (1): 81-105. 

Similä, T., Holst, J.C and Christensen, I 1996. Occurrence and diet of killer whales in 

northern Norway: seasonal patterns relative to the distribution and abundance of Norwegian 

spring-spawning herring. Can. J. Fish. Aquat. Sci. 53: 769-779. 

Similä, T. 1997. Behavioural ecology of killer whales in northern Norway. PhD thesis, 

NFH, University of Tromsø 1997. 



135

CLICKS, CALLS AND UNDERWATER TAIL-SLAPS; SOUNDS OF NORWEGIAN 

KILLER WHALES. 

1 1 2 1 

Simon M. , Miller L. , Ugarte F. , Wahlberg M. . 

1 Center for Sound Communication, Institute of Biology, SDU-Odense, Denmark; 

msimon@post.tele.dk 

2 Allégade 23B 3.th, 2000 Frederiksberg, Denmark. 

The presentation concerns the sounds produced by Norwegian killer whales during the 

herring wintering season. There were two goals; first to measure source levels and spectral 

characteristics of sounds produced by killer whales while feeding on herring and secondly to 

describe the relationship between the vocalisations and the activity of Norwegian killer 

whales. For the first, killer whales were recorded using a four-hydrophone array (recording 

bandwidth: 1Hz to either 150 kHz or 300 kHz). In order to estimate apparent source levels 

(ASL), the distance to the whales was estimated from the differences in the time of arrival of 

the sound to the hydrophones. For the second, sound recordings in the proximity of whales 

were made using a recording system with a frequency range of 20Hz to 20kHz. One out of 

four activity states (feeding, travelling, resting or socialising) were assigned to the whales by 

an experienced observer. Five minute samples of 40 recording sessions (10 samples for each 

activity state) were analysed. Preliminary results suggest that the presumed echolocation 

clicks of these killer whales are broadband, with centre frequencies of 26-57 kHz. The 10 dB 

bandwidth was 12-32 kHz and the average click duration was 38 µs. ASL’s ranged from 187 

to 213 dB re. 1µPa (p-p) @ 1m (n = 52 clicks, including clicks on- and off-axis). The 

underwater tail-slaps, used by the whales to stun herring, produced multi-pulsed broadband 

sounds with ASL of 187 dB re. 1µPa (p-p) @ 1m (n = 1). Feeding behaviour was 

characterised by high vocal activity and was the only activity where tail-slaps occurred. In 

general, killer whales travelled in silence. Most whistles were heard during socialising. 

Resting behaviour was not clearly defined acoustically. 



136

AERIAL VOCALISATIONS OF KILLER WHALES TEMPORARILY CAPTURED 

IN NORTHERN NORWAY. 

Simon M.J. 1 , Ugarte F. 2 . 

1 Inst. Biology, University of Odense, Campusvej 55, 5230 Odense M., Denmark., 

msimon@post.tele.dk; 2 Allégade 23 B, 3.th. 2000 Frederiksberg. Denmark. 

The aim of this study is to describe the vocalisations of two temporarily captured killer 

whales. During satellite tagging of killer whales in northern Norway, two killer whales were 

lifted to the deck of a tagging vessel. On deck, the vocalisations and blows of the whales were 

recorded using a DAT recorder and a directional microphone placed 0,5 m. in front of the 

whale. 65 minutes of sounds were analysed using Avisoft Lab software. No whistles were 

produced and only a few isolated echolocation clicks appeared. Each whale repeated one or 

two compound calls made of two to three elements. The elements could appear alone, in pairs 

or in triads. When in pairs or triads, the elements always followed the same order (e.g.: abc, 

ab, ac or bc). To our knowledge, compound calls among odontocetes have only been 

described for Norwegian killer whales. Under water recordings of the pod of one of the 

whales are being analysed for call matches. So far, the call produced by the captured whale 

has not been found in these recordings. Being cautious about small sample size (n = two 

captures), the fact that both whales used only compound calls, suggest that compound calls 

can be used in emotional contexts, such as stress. The fact that the vocalisation emitted by one 

whale has not been heard during the recordings of its pod while engaged in different 

behaviours, suggests that this particular vocalisation is used during specific contexts. The fact 

that two whales caught, belonging to two different pods, produced different calls, indicate that 

these calls belong to the pod specific dialect. 



137

INTERACTIONS BETWEEN KILLER WHALES (ORCINUS ORCA) AND RED 

TUNA (THUNNUS THYNNUS) FISHERY IN THE STRAIT OF GIBRALTAR 

de Stephanis R. 1 , Pérez Gimeno N. 1 , Salazar Sierra J. 1 , Poncelet E. 2 , Guinet C. 3,1 . 

1 CIRCé Cabeza de Manzaneda 3, Pelayo, 11390 Algeciras, Cadiz, Spain, renaud@teleline.es ; 

2 1, allée des Oliviers, 06400 Cannes, France; 3 CEBC-CNRS, 79360 Villiers-en-Bois, France 

INTRODUCTION 

Sightings of Killer Whales have been reported in the area of The Strait of Gibraltar for 

more than 500 years. (Bayed and Beaubrun, 1987, Aloncle, 1964, Morcillo, pers comm). 

This area is also very important for tuna fisheries. The Red Tuna (Thunnus thynnus) 

migrates every year throughout The Strait of Gibraltar entering the Mediterranean sea in 

spring to breed, and leaving the Mediterranean sea in summer (Rodriguez, J. 1964). For the 

last 500 years, the traditionnal way of fishing Red Tuna has been the Almdraba (pound nets), 

where the Killer Whales were interacting in the Strait and in close tuna fisheries areas 

(Morcillo, M., pers. com.). 

This large fast swimming fish species appears to be the main fish prey of Killer Whales 

in the area in spring and summer. 

In the last decade fishermen have been starting to use drop lines to catch the Red Tuna, 

and it is just this interaction that is the topic of the study.This research project started in 1998 

in The Strait of Gibraltar using different whale-watching boats. In 2001 and 2002 the project 

starts to works from the research boat ELSA. 

METHODOLOGY 

During the year of 1998, interviews to fishermen were carried out in order to know 

exactly where the fishing boats were seeing the Killer Whales and the possible interactions 

with them in the area of Tarifa. During the years 1999 and 2000, whale watching trips were 

carried along the Strait of Gbraltar, and the killer whales were observed around the fishermen, 

in the West area of the Strait. In the summers of 1999 and 2000, 16 dedicated Killer Whale 

whale-watching trips with one or two experienced observers onboard were carried out in the 

study region. These trips had an average duration of 3:50 hrs and two different boats ,of 7 and 

9-m long, were used for this purpose between 22th July and 20th August of both years. Data 

concerning number of individuals, social structure, and general behaviour were recorded, and 

pictures of the dorsal fins were taken for identification purposes in each one of the sightings, 

although not all the animals were photographed in each sighting due to the whale watching 

conditions. During the years 2001 and 2002 aleatoric research trips were carried along the 

Strait of Gibraltar. Those transects can be seen in FIG 1.-2 

Observations regarding to the depredation of tuna from the drop line by the Killer 

Whales, as well as the reactions of the fishermen were also recorded. Furthermore, the 

number and type of fishing vessels observed around the group of animals were also identified. 

RESULTS SIGHTINGS 

Between 1998 and 2002 around 14 000 nautical milles ahve been sailed in the Strait of 

Gibraltar resulting in 1898 sightings of Common Dolphins (Delphinus delphis), Striped 

Dolphins (Stenella coeruleoalba), Bottlenose Dolphins (Tursiops truncatus), Long Finned 



138

Pilot Whales (Globicephala melas), Sperm Whales (Physeter macrocephalus) Fin Whales 

(Balaenoptera physalus) and Killer Whales. 

Killer Whales were only observed in the western past of the Strait.This area is centred 5 

miles north of Tanger, next to the sea mountains "Monte Tartesos", "Cañón de Bolonia" and 

"Cresta Kmara" 

Between 1999 and 2002, 35 sightings of Killer Whales were recorded in this area, and 1 

sighting was also made in at the south of Barbate, at the north-west of the Strait. (See FIG 

3). This last sighting was made during the month of April, while the rest of the sighting were 

made during the month of July and Augus t. 

Results Behaviour 

The animals were observed during a total of 105 hours and 19 minutes. The behaviours 

recorded were socialising, for 36min ( 0,6 %), and feeding during 104 and 43 min (99,4 %). 

Killer Whales were observed in the presence of fishing boats where the average abundance 

was 102 within a radius of 700-1000 meters in 30 ocasions. The rest of the sightings (6) the 

killer whales were observed feeding without fishing boats around. Witnessed interactions 

consisted of either removing the fish from the drop line hooks or biting the caught fishes. 

Results Identification 

Photos of the animals' dorsal fin were taken in 30 of the sightings, which were classified 

in three categories: bad, good, and excellent, and only the pictures included in the last two 

categories were taken into account for photo-identification purposes. Between 17 and 18 

Killer Whales were captured Between 1999 and 2002. Between 12 and 13 individuals were 

observed interacting with Tuna fisherys, and 5 individuals were observed at the south of 

Barbate, in April 2002.. 

DISCUSSION 

The Group Of Killer Whales 

The data reveals the presence of a stable group of at least 12 individuals of Killer 

Whales in the western part of the Strait, while the identification of a 13th needs confirmation. 

The observation of the feeding behaviour and the fact that no attack of the Killer 

Whales to other prey was observed, suggest that the main diet during the summerand spring 

period should be Red Tuna. 

Interactions With Fisheries 

According to the records, when the fish is being lifted, the Killer Whales try to steal or 

bite it. This competition for the same resource (Red Tuna Fish), is the main reason why so 

many interactions between Killer Whales and fisheries have been described in the region for a 

long time. In certain times, it seems that fishermen really dislike these attacks of the Killer 

Whales, and they can even throw stones over them, or try to scare them by riding the boat 

over them. On 26th July 2000, a shoot-like sound was recorded, but it was not possible to 

clarify if it was only to threat the animals or to hurt them. 

Beside this, the fast development of the whale watching platforms in the area (5 to 6 

boats are awaited for this summer 2003) (Urquiola and de Stephanis, 2000) the presence of 

some research vessels (3 boats are awaited for the summer 2003), the interests for the mass 

media (local and international T.V. channels), and the local political problems regarding the 

fishing international agreements could create management problems between these sectors 

and the fishing community, and could interfere in this Killer Whales group. 



139

CONCLUSIONS 

In the summers 1999 and 2002, a group of between 12 and 13 animals at least regularly 

took advantage of the presence of a drop line fishery west to The Strait of Gibraltar to obtain 

easy food by stealing hooked fishes. This group has probably specialised in this feeding 

strategy. Clear interactions between fishing boats and Killer Whales exist in the area during 

the summers. 

These interactions and the depletion of the Red Tuna stocks due to over fishing is likely 

to result in negative impacts on both Killer Whales and fishermen in this area. Management 

procedures should be developed, to preserve Killer Whales and the interest of fishermen. 

AKNOWLEDGEMENTS 

Special Thanks to all the institutions that sponsorised this project: 

1998-2000: FIRMM: foundation for Information and research on marine mammals, 

Whale watching platform of the Strait of Gibraltar, 2001: Autonomous City of Ceuta, 2002: 

BBC: British Braodcast Corp and LIFE02NAT/E/8610. Special Thanks also to all the 

volunteers that colaborated in the data colection and data analyse. Thanks to all the fishermen 

that had to see us during those 4 summers. They were really patient with us... Thanks to the 

captains who patiently supported us in the campaigns we carried out, in particular to Antonio, 

Andres, Juan, Miguel and Kiko. To all the staff members of the different whale watching 

platforms, in special to Walti, Keti and all the volunteers of those platforms. Last but not 

least, to the “Torre de Salvamento Marítimo de Tarifa Tráfico”. 

REFERENCES 

BAYED, A. & BEAUBRUN, P.-Ch., 1987. Les mammifères marins du Maroc : 

inventaire préliminaire. Mammalia, 51(3): 437-446. 

ALONCLE, H., 1964. Premières observations sur les petits cétacés des côtes 

marocaines. Bulletin de l'Institut des Pêches Maritimes du Maroc, 12: 21-42. 

URQUIOLA, E., DE STEPHANIS, D, 2000. "Growth of whale watching in Spain. The 

Sucsses of the platforms in south mainland. New rules". In European Research on Cetaceans 

14. G. Donovan (ed.). Proc. 14 th Ann. Meeting European Cetacean Society, Cork, Ireland, 5- 

9 April. In press. 



140

FIG.1: Research Area 

FIG.2: Aleatoric transects realised along the Strait of Gibraltar durring 2001 and 2002 from the research boat 

ELSA 



141

FIG.3: Sigtings of Killer whales during 1998-2002 in the Strait of Gibraltar 



142

THEODOLITE STUDY OF THE EFFECTS OF VESSEL TRAFFIC ON 

KILLER WHALES (ORCINUS ORCA) IN THE NEAR-SHORE WATERS OF 

WASHINGTON STATE, USA (POSTER) 

Smith J.C.¹, Bain D.E.² 

¹Orca Conservancy, 219 1st Avenue South, Suite #315 Seattle, WA 98104, USA, 

dyesqueen@rockisland.com ; 

²Six Flags Marine World Vallejo, Vallejo, CA 94589, USA, dbain@u.washington.edu 

Beginning in 1999 a shore-based theodolite tracking study was set up to look at the 

relationship between whale watching vessels and killer whale behavior, as well as a way of 

measuring compliance of the self imposed no-boat corridor within a ¼ mile of shoreline when 

whales are present. Measurements included dive times, swim speeds, surface behaviors, and 

distance offshore of whale watch operators. 

RESULTS 

This study tested the null hypothesis that whale indices are independent of vessel 

activity. Null hypothesis being rejected would indicate whale response may be related to the 

intensity of whale-watching in a non-linear manner. 

Directness Index 

A statistical finding (Table 1) resulted from looking at the directness index with and 

without boats present. The mean with boats was 83.28 while the mean without boats was 

91.47. Whale paths were direct with no boats, more deviation occurred with boats numbering 

between 6 and 25, gradually becoming more direct as boat numbers climbed towards 30 

(Figure 1). 

Distances Offshore 

Whales were tracked offshore with a median distance of less than 400 meters of the 

shoreline each year of the study. Year 2001 showed the continuation of this. 

¼ Mile Compliance 

Numbers of observations of commercial whale watching boats showed their distribution 

peak just outside the ¼ mile line of 400 meters. When compared to Soundwatch present or 

absent, commercial compliance went down for 2001. 22.54% were within 350 meters when 

Soundwatch was present, while 13.16% were inside 400 meters while Soundwatch was 

absent. 

Non commercial private boats stayed within the ¼ mile zone roughly half of the time. 

These boat types encompass fishing vessels and kayaks, that aren’t asked to move offshore by 

Soundwatch, or ocean-liners that naturally stay offshore. 

DISCUSSION 

Tracking whales in the absence of boats has proven to be significantly difficult due to 

the increased numbers of hours boats are around whales. Boats appear to be accompanying 



143

whales for up to 10 hours a day, seven days a week. Length of time spent with whales varied 

between the hours of 0600 until after dusk, (~2100 h). For each of the past two years of the 

study only 9% of whale passes were without boats, although 2001 held a higher percentage of 

‘no-boat’ tracks than previous years. In addition, in year 2000 data there seems to be a slight 

yet significant trend for animals to increase distance traveled in the presence of a few boats. 

Whales were direct with zero boats, and then adopted a less direct path with boats numbering 

between 4 and 17. This trend was found to exist in the 2001 data as well. 

The assumption that boats do not affect whale behavior was violated. However, due to the 

small sample size, other assumptions such as tidal and current states, time of day, time of 

year, age, sex and group dynamics, were not important factors, but may have been violated in 

addition. More tracks would allow for the breakdown of these variables and more confidence 

in assumptions. Samples of ‘boat’ tracks numbering around 40 didn’t result in significant 

change from year to year but ‘no-boat’ type tracks changed going from 8-12 samples. 

Clearly it would be of tremendous value to get a large number of no-boat tracks in a single 

season. Because of the small number of low directness index tracks, it is unsure if the 

quantitative results of the statistical test overstate the probability that this is true. 

Compliance regarding the ¼ mile has been easily determined during this study. 

For 1999 and 2000, private vessels complied with the ¼ mile ‘no-boat’ zone 55% of the 

time; commercial whale watchers were just under 80 of the time. Year 2000 showed the 

effectiveness of the Soundwatch Boater Education Program, with a 90% compliance by 

commercial whale watchers, when Soundwatch was present. Unfortunately year 2001 

showed decreased time on the water by Soundwatch and a decrease in distance offshore by 

commercial whale watch operators by roughly 50 meters. 

The results presented here show a statistically significant trend for boat traffic to disrupt 

short-term behavior of individual killer whales. If boat traffic generally forces animals to 

swim further, then this carries an obvious metabolic cost. Paired with a decreasing food 

source and heavy contaminant load, short-term responses should not be dismissed. 



144



145

OBSERVATIONS OF KILLER WHALES DURING THE FALL, WINTER AND 

SPRING IN SOUTHEASTERN ALASKA 1980-2002 

Janice M. Straley 1 and Graeme Ellis 2 

1 University of Alaska Southeast Sitka Campus, 1332 Seward Ave., Sitka, Alaska 99835 USA 

2 Pacific Biological Station. Fisheries and Oceans Canada, Nanaimo, BC Canada V9T 6N7 

ABSTRACT 

Killer whales frequent the coastal rim of the North Pacific during all months of the year, 

however, little is know of their distribution during the fall, winter and spring. Data reported 

here were collected in the waters of southeastern Alaska across the years1980-2002. These 

data resulted in 20 encounters with killer whales in 11 of the 22 survey years. Most (18) 

encounters were observed from 1993 to 2002. The number of encounters per year ranged from 

one to four. Observations occurred from September through May with no killer whales 

observed in December. There were 99 sightings of killer whales during these encounters 

representing 44 different whales. Most (25) of these 44 killer whales were sighted only once. 

Group size ranged from 1 to 14 with an average of 5.0 (se=0.68) whales per group. Killer 

whales observed during this study were associated with mammal eating or ‘transient’ 

populations that range along the western coast of the United States and Canada. Behavior 

included foraging near shore (40%), traveling (35%), predation or feeding (15%), milling 

(10%). Milling occurred near feeding humpback whales, Steller sea lions, harbor porpoises 

and Dall’s porpoises. All predation events (n=3) were upon marine mammals (harbor seal or 

Steller sea lion or Dall’s porpoise). In summary, this study has provided insights into the 

importance of southeastern Alaska, a complex coastal fjord habitat, by killer whales during 

the fall, winter and spring. 

INTRODUCTION 

Killer whales frequent the coastal rim of the North Pacific during all months of the year, 

however, little is known of their distribution and foraging behavior in the fall, winter and 

spring in the eastern North Pacific. The killer whales that roam the waters of southeastern 

Alaska are closely linked with the whales seen to the south, in British Columbia, Canada 

(Ford and Ellis 1999). This ongoing study of killer whales is a first step towards 

understanding the distribution and foraging behavior in Alaskan waters during the fall, winter 

and spring. 

METHODS 

The results presented in this paper summarize data collected on killer whales across 22 

years, from 1980 to 2002. During 1980 to 2000 opportunistic studies occurred in conjunction 

with research on humpback whales and in 2001 and 2002 directed studies were conducted 

specifically on killer whales. All observations were during the fall, winter and spring in 

southeastern Alaska (Figure 1). Small boats less than 8m were used to record observations of 

killer whales and 35mm SLR cameras were used to obtain photographs of dorsal fins and 

saddle patches of individual killer whales. Killer whales were identified as to ecotype based 

upon association with other known killer whales in the same population. 



146

Southeaster 

n Alaska Study 

Figure 1. Map of North Pacific Ocean with arrow pointing to the southeastern Alaska study 

area. 

RESULTS 

A total of 44 different killer whales were seen 99 times. The majority of the killer 

whales were observed once (25 whales) and one killer whale was seen six times (Figure 2). 

New killer whales continued to be identified in the study area. Three new killer whales were 

identified in 2002. There were 20 encounters with killer whales with group size ranging from 

1 to 14 whales (mean=5.0 whales, se=0.68, Table 1). All killer whales observed were 

transients or the mammal-eating ecotype. 

Table 1. Group size and date of encounter for killer whales seen during fall, winter and spring in southeastern 

Alaska, 1980 to 2002. 

Date Group size Date 

Group 

size 

11-Feb-80 6 11-Nov-98 3 

07-Sep-84 3 10-Mar-00 6 

10-Jan-93 3 17-Mar-00 2 

16-Feb-94 7 04-Apr-00 8 

24-Mar-95 7 28-May-01 6 

04-Jan-96 14 24-Feb-02 6 

29-Oct-96 2 23-Mar-02 3 

09-Jan-97 6 06-Sep-02 2 

04-Feb-97 5 07-Sep-02 2 

05-Nov-97 7 12-Sep-02 1 



147

NUMBER OF SIGHTINGS 

30 

25 

20 

15 

10 

5 

0 

1 2 3 4 5 6 

NUMBER OF WHALES 

Figure 2. Number of times individual killer whales were sighted across the study period, 1980 to 

2002. 

Most of the encounters (18 out of 20) occurred from 1993 to 2002 and the number of 

killer whales encounters increased in 2002 (Figure 3). 

ENCOUNTERS 

6 

5 

4 

3 

2 

1 

0 

1980 

1982 

1984 

1986 

1988 

1990 

1992 

YEAR 

Figure 3. Number of killer whale encounters each year in southeastern Alaska, 1980 to 2002. 

There were discernable peaks in the presence of killers whales by month and the most 

encounters occurred in the winter months and in September (Figure 4). 

1994 

1996 

1998 



2000 

2002 

148

ENCOUNTERS 

5 

4 

3 

2 

1 

0 

SEP OCT NOV DEC JAN FEB MAR APR MAY 

MONTH 

Figure 4. Killer whale encounters each month during fall, winter and 

spring in southeastern Alaska, 1980 to 2002. 

The primary behavior observed during the 20 encounters of killer whales was foraging 

within 1.6km of shore, occurring 40% of the time. The next most common behavior observed 

was fast travel, which was seen in 35% of the encounters. Milling occurred 10% of the time 

near feeding humpback whales, Dall’s and harbor porpoises, Steller sea lions and harbor 

seals. Feeding was observed three times (15% of the time); once on a Dall’s porpoise, once 

on a Steller sea lion and once on either a sea lion or seal. 

CONCLUSIONS 

Transient killer whales were they only type of killer whale encountered during the fall, 

winter and spring in southeastern Alaska from 1980 to 2002. Observations of higher number 

of transients during the fall, winter and spring were consistent with what has been observed in 

British Columbia, however, they do see smaller resident (fish eating) groups occasionally 

(Ford et al. 1998). The occurrence of transient killer whales near coastal areas coincides with 

the habits of the prey of the different killer whales, transient prey is available year round and 

salmon, a migratory species and primary prey of residents, are less available. 

There were discernable peaks in the presence of killers whales by month. The 

September peak could be due to better sighting conditions and more vessels on the water to 

report whales before the fall and winter storms begin. The January through March peaks are 

likely due to an increase in Steller sea lions which inhabit Sitka Sound feeding on herring 

which are present in the deep coastal fjords in winter. The increase in the number of killer 

whales observed in 2002 could be due to a change in the number of killer whales or a shift in 

habitat use. However, the most likely reason for this increase is the start of dedicated survey 

effort on killer whales in 2001, which began in earnest in January 2002 when a 

comprehensive reporting network was established. 



149

REFERENCES 

Ford, J.K.B and G. Ellis. 1999. Transients: Mammal-Hunting Killer Whales of British 

Columbia, Washington and Southeastern Alaska. University of British Columbia Press, 

Vancouver, BC 96pp. 

Ford, J.K.B., G.Ellis, L.G.Barrett-Lennard, A.B. Morton, R.S. Palm, K.C. Balcomb III. 1998. 

Dietary specialization in two sympatric populations of killer whale (Orcinus orca) in 

coastal British Columbia and adjacent water. Can. J. Zool. 76:1456-1471 



150

WHAT IS THE FAVOURITE PREY ? FORAGING ECOLOGY OF KILLER 

WHALES AT AVACHA GULF, RUSSIAN FAR EAST. 

Tarasyan K., Jikiya E. 

Russia, 119899, Moscow,Moscow State University,Biology Faculty, Department of Zoology 

Vertebrate, karen@ntl.ru 

Kamchatka killer whale population is studied since 1999 up to a present year by the 

scientific expedition organized by Kamchatka Institute of Ecology and Nature Management 

and Moscow State University. Methods of our research are traditional for investigations of 

cetacean: we use photo-identification technique, acoustic analyzing and land-based behavioral 

observations simultaneously. 

This report represents some aspects of foraging ecology of killer whales at Avacha Gulf, 

Russian Far East, based on two-year behavioral data. It is known that killer whales use 

different methods for different fish prey. We has distinguished two hunting methods: long 

diving of single killer whale, which is not coordinated with other group members, used for 

catching single fish, and “karusel” method, described for killer whales and other cetacean 

during chasing fish schools by the group of dolphins. Perquisition of local fishermen has 

allowed finding out the basic species of the fishes, which inhabit at Avacha Gulf. Some of 

these species, such as walleye pollock, greenlings, codfish or flounder, have commercial 

value. Behavior and position of orcas during foraging let us to predict fish species, which are 

hunted by observed killer whales. 

Varying ratio of two types of fish chasing and changing places of foraging from season 

to season allows to assume, that the basic food objects, attracting killer whale to Avacha Gulf, 

are changing from year to year, depending basically on large number and availability of 

separate possible prey species. 



151

POPULATION VIABILITY ANALYSIS FOR THE SOUTHERN RESIDENT 

ABSTRACT 

POPULATION OF KILLER WHALES 

Taylor M., Plater 

Center For Biological Diversity, B. PO Box 40090, Berkeley, CA 94704, 

bplater@biologicaldiversity.org 

Population viability analysis by stochastic population modeling suggests that the 

Southern Resident population of killer whales is likely to become extinct in the foreseeable 

future unless ongoing habitat degradation is halted. Only the most optimistic models free of 

adverse impacts to habitat resulted in predictions of population stability. Incorporation of 

plausible impacts such as oil spills, epizootics, and reduced salmon food stocks greatly 

increased predicted extinction risk, even under the optimistic assumption that the long-term 

average fecundity and mortality observed in the population would otherwise continue 

unchanged. If the reduced fecundity and adult survival seen in the population since 1996 is 

assumed to continue indefinitely rather than return to the lower levels seen over the previous 

22 years, the risk of extinction of the Southern Resident population within 100 years is highly 

likely, even in the absence of additional threats to the population. 

The most plausible scenario, incorporating risks of inbreeding depression and 

mate limitation at small population sizes, risks of oil spills, epizootics, and reduced food 

supply predicted a median time to extinction of 74 years with a 95% confidence interval of 

33-121 years. However, adult mortality may increase further if recent trends continue. If 

adult mortality continues to increase at the same rate, then extinction risk would be even 

higher. 

INTRODUCTION 

Once abundant throughout the waters of the Pacific Northwest region of the United 

States and Canada, the Southern Resident killer whale has been declining since 1996 and is 

now one of the most imperiled killer whale populations in the world. The decline has been 

attributed to several anthropogenic sources, primarily depletion of preferred food stocks, toxic 

pollution, and disturbance from whale watching boats and other shipping traffic. We 

conducted a Population Viability Analysis to determine the likelihood of the population going 

extinct if these threats continue unabated. 

Killer whales in the Pacific Northwest are divided into three forms: Residents, 

Transients, and Offshores. The forms are distinct genetically, behaviorally, and 

morphologically, but occupy adjacent or overlapping ranges (Baird 1999). Although the 

forms are distinct enough to be classified as separate subspecies or even species, all are 

currently classified as one species. 

Resident killer whales in the Pacific Northwest are divided into two populations: 

Northern Residents and Southern Residents. Each stock has distinct patterns of association, 

pigmentation and genetics (Bigg et al. 1987, Baird and Stacey 1988, Bain 1989, Ford et al. 



152

1998, Hoelzel et al. 1998, Matkin et al. 1998, Barrett-Lennard 2000). Although the Resident 

populations have partly overlapping ranges, behavioral interactions are rare. Genetic and 

morphological differences suggest that they have been reproductively isolated for thousands 

of years (Baird and Stacey 1988, Stevens et al. 1989, Hoelzel and Dover 1991, Hoelzel et al. 

1998, Barrett-Lennard 2000). 

POPULATION TRENDS, 1973-2002 

The Southern Residents have declined precipitously since 1996. This ongoing decline 

is unlike any earlier decline seen in this population because it involves elevated mortality of 

young adults and reduced fecundity. The decline has caused Canada to list the Southern 

Residents as “endangered.” However, the United States has declined to protect the whales, 

despite the fact that government scientists found that the population is both discrete and 

endangered. 

METHODS 

Population size 

100 

90 

80 

70 

67 

71 71 71 

81 

80 

79 

83 

81 

78 

76 

74 

76 

81 

84 84 85 84 

90 91 

96 

94 

96 97 

60 

1973 1975 1977 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 

FIGURE 1. Population Trends for Southern Residents Since 1973 

The published record of births and deaths for the period 1973-2002 from the Center for 

Whale Research with corrections by University of Washington whale biologist Dr. David 

Bain were used to calculate age and sex distributions, and annual mortality and fecundity 

statistics. 

Best estimates of life history variables were then used for successive simulations of the 

Vortex modeling algorithm (Lacey et al., 2000). Stochastic population simulations were run 

for 18 different sets of parameters. All models, however, assumed that no trends in 

parameters exist; that the Southern Residents are freely polygamous, mating in a single 

panmictic population without social structure; that the age of first breeding is 16 years for 

both sexes; that the maximum breeding age for each sex is 40 years; that no twinning occurs; 

and that there is no concordance in environment variance in mortality & fecundity. 

The most plausible model: sets inbreeding effects at 2 lethal equivalents, a conservative 

estimate; has a 50% primary sex ratio, a conservative ratio in light of the observed sex ratio 

of 57% males in the population; maintains fecundity and juvenile mortality levels at the long- 



91 

89 

84 

82 

78 79 

153

term averages for the population; sets adult mortalities at the elevated levels seen between 

1996-2001 because the elevated mortality of adults is a novelty in the 28 year record of 

observation; incorporates a declining carrying capacity to model food scarcity; incorporates 

an Allee effect to model the likely effects of mate limitation at low population sizes; and 

models oils spill and epizootic risks based on impacts seen in other killer whale and marine 

mammal populations that have been exposed to these threats. Results of 17 other model runs 

are not shown here. 

RESULTS: MOST PLAUSIBLE MODEL SHOWS EXTINCTION IMMINENT 

For this scenario, predicted extinction risk was high within 100 years, with 

median time to extinction of only 74 years with a 95% confidence interval of 33 - 121 years. 

The population trajectories of the simulations showed wide variability (Fig. 2). Note that time 

at which median predicted population size reaches zero is not the same as median time to 

extinction. Extinction is defined as extinction of one sex, and so is expected to occur earlier 

than death of all individuals. 

Population 

110 

100 

90 

80 

70 

60 

50 

40 

30 

20 

10 

0 

0 20 40 60 80 100 120 140 160 

FIGURE 2. Extinction Trajectory of Southern Resident Killer Whales 

The results suggest that the Southern Resident population is very likely to become 

extinct in the foreseeable future unless action is taken to arrest declining habitat quality. 

Protection for this population is urgently needed so that the population can survive any future 

catastrophes or perturbations. Effort should therefore be directed at identifying the causes of 

the recent increases in adult mortality and declining fecundity and at finding ways of halting 

or mitigating any human impacts that might be implicated. If the higher risks of death and 

impaired reproduction created by oil spills, salmon reduction, pollution and disease are 

reversed, then there is a low likelihood of extinction in the foreseeable future. If these risks 

are not substantially removed, extinction is certain. Governments should engage protective 

measures such as the United States Endangered Species Act to adequately address the threats 

facing the Southern Residents. 

Time 



154

LITERATURE CITIED 

Bain, D.E. 1989. An evaluation of evolutionary processes: studies of natural selection, 

dispersal, and cultural evolution: I Killer Whales (Orcinus orca). Ph.D. Thesis, University of 

California, Santa Cruz. 

Baird, R.W. 1999. Status of Killer Whales in Canada. Report to the Committee on the 

Status of Endangered Wildlife in Canada (COSEWIC), Ottawa. 

Baird, R.W. and Stacey, P.J. 1988. Variation in saddle patch pigmentation in 

populations of Killer Whales (Orcinus orca) from British Columbia, Alaska, and Washington 

State. Can. J. Zool. 66, 2582-2585. 

Barrett-Lennard, L.G. 2000. Population structure and mating patterns of killer whales 

(Orcinus orca) as revealed by DNA analysis. PhD Thesis, University of British Columbia, 

Vancouver, B.C. 

Bigg, M.A., G.M. Ellis, J.K.B. Ford, and K.C. Balcomb. 1987. Killer Whales: a study of 

their identification, genealogy, and natural history in British Columbia and Washington State. 

Phantom Press, Nanaimo, B.C. 

Ford, J.K.B., G.M. Ellis, L.G. Barrett-Lennard, A.B. Morton, R.S. Palm, and K.C. 

Balcomb. 1998. Dietary specialization in two sympatric populations of Killer Whales 

(Orcinus orca) in coastal British Columbia and adjacent waters. Canadian Journal of Zoology 

77: in press. 

Hoelzel, A.R., and G.A. Dover, 1991. Genetic Differentiation Between Sympatric Killer 

Whale Populations. Journal of Heredity, 66:191-195. 

Hoelzel, A.R., M. E. Dahlheim and S.J. Stern, 1998. Low genetic variation variation 

among killer whales (Orcinus orca) in the eastern North Pacific and differentiation between 

foraging specialists. J. Heredity 89, 121-128. 

Lacey, RC, Hughes, KA and Miller, PS (2000) Vortex: a stochastic simulation of the 

extinction process. Chicago Zoological Soc. 

Matkin, C.O., D. Schel, G. Ellis, L. Barrett-Lennard, H. Jurk and E. Saulitis. 1998. 

Comprehensive Killer Whale investigation, Exxon Valdez oil spill restoration project annual 

report (Restoration Project 97012). North Gulf Oceanic Society, Homer, Alaska. 

Stevens, T.A., D.A. Duffield, E.D. Asper, K.G. Hewlett, A. Bolz, L.J. Gage, and G.D. 

Bossart. 1989. Preliminary findings of restriction fragment differences in mitochondrial DNA 

among Killer Whales (Orcinus orca). Canadian Journal of Zoology 67:2592-2595. 



155

PREDATION BEHAVIOR OF TRANSIENT KILLER WHALES IN MONTEREY 

BAY, CALIFORNIA 

Ternullo R., Black N. 

Monterey Bay Cetacean Project, P.P. Box 52001, Pacific Grove, CA 93950, rternullo@aol.com. 

INTRODUCTION 

Monterey Bay, located along the central California coast, is affected by strong 

seasonal upwelling, providing rich primary production. This in turn provides a reliable food 

source that supports four species of pinnipeds, two species of porpoise, six species of 

dolphins, at least four species of baleen whales, and numerous species of seabirds. Of the 

three ecotypes of Killer Whales known for the eastern North Pacific, transients (marine 

mammal predators) are most frequently sighted. 

METHODS 

For each Killer Whale sighting, we attempted to photo-identify all whales within a 

group. Data collected for each group included sighting location, movements, and behavior of 

transient groups. If prey species were encountered, we attempted to identify them, and noted 

if they were harassed, attacked, or consumed. When possible, predation events were 

videotaped to analyze hunting strategies and roles of specific Killer Whales. 


Proportion of prey items observed for 84 events documented since 1987 included 

California Sea Lion (35%), Gray Whale calf (30%), and 10 % or less in descending order for 

Dall’s Porpoise, Northern Elephant Seal, seabird, Harbor Seal, Pacific White-Sided Dolphin, 

and Common Dolphin. Killer Whales occurred in greatest numbers either when prey items 

were in abundance or their young were setting out to sea for the first time. A peak in transient 

Killer Whale sightings occurred during late spring when Gray Whale calves and their mothers 

are transiting Monterey Bay on their northward migration. Northern Elephant Seals and 

Pacific Harbor Seals were also weaning their young at approximately the same time. There 

was then a decline in Killer Whale sightings until late August and sightings increased 

throughout the fall corresponding with an influx of California Sea Lions and Elephant Seals at 

sea, then declined again until early spring. On average there were about forty to fifty sightings 

per year. Killer Whale group sizes varied by prey type with an average group size of three for 

Dall’s porpoise attacks to 13 for attacks on Gray Whale calves. 

California Sea Lions were the most numerous prey items, and all age classes of Sea 

Lions were taken. Predation events on this species were very visible due to the relatively long 

process of incapacitating the Sea Lion by tossing, body and tail slams, and then in most cases, 

ending the attack by drowning the prey. In some cases, the Sea Lion was battered, drowned 

and killed, then towed along with the Killer Whales for several hours. 

Harbor Seals have been identified as prey items from fur fragments or brief glimpses 

of the seal’s presence before it was killed. They are possibly under-reported because of the 

cryptic and quick killing process used on these seals. 

All age classes of Northern Elephant Seals were taken. Adult male Elephant Seals 

appeared to be prevented from taking deep dives by the Killer Whales and drowning was the 

suspected cause of death, often lasting up to an hour. Weaners were often taken quickly at the 

surface and a round of pummeling with flukes led to eventual drowning. There has not 



156

een an observed attack on Northern Fur Seals, but they are known as prey for transients in 

this population. Their behavior of resting on the surface or in kelp paddies with little 

movement for long periods of time may be an advantageous strategy to avoid detection by 

Killer Whales. 

Both Dall’s and Harbor Porpoise are present in Monterey Bay, but only Dall’s Porpoise 

have been recorded as prey items. Killer Whales travelling through the Bay were closely 

associated with the edge of the Monterey Submarine Canyon, an area where Dall’s Porpoise 

occur, whereas Harbor Porpoise inhabit near-shore shallow waters where Killer Whales rarely 

occur. Attacks on Dall’s porpoise involved a quick rush by the Killer Whales, then the 

porpoise was often popped up in the air by the head of the whale, or else there was a quick 

chase and bite which mortally wounded the porpoise. Porpoise were taken by surprise and 

quickly killed. 

Of six dolphin species commonly seen in Monterey Bay, only Pacific White-Sided 

Dolphin and Long-Beaked Common Dolphin have been attacked and killed by transients. 

These dolphins often travel in large groups of 100-2000+, and Killer Whales often quietly 

trail the group for awhile before choosing one that lags behind. Both species exhibited a 

strong flight response whenever Killer Whales were detected, therefore proving a difficult 

prey item to catch. 

Four species of baleen whales are commonly seen in Monterey Bay: Humpback 

Whales, Blue Whales, Gray Whales, and Minke Whales. Of these only Gray Whales were 

observed during attacks by Killer Whales. Humpback and Blue Whales both bear many 

indications of struggles with Killer Whales on their bodies and flukes; i.e. tooth rake marks 

from Killer Whales on tail flukes. One beached Minke Whale had evidence of Killer Whale 

predation. Due to the extreme damage on some Humpback Whale flukes, predation attempts 

obviously take place, but they may not occur in California waters. Several observations of 

Killer Whales pursuing and harassing Blue Whales exist for the study area. 

Gray Whales and particularly their calves seem to provide a significant food resource 

on a seasonal basis. During the mother/calf phase of the northern Gray Whale migration there 

appears to be a location of high vulnerability associated with particular areas of Monterey Bay 

and its complex canyon system. 

Gray Whales that migrate through Monterey Bay either pass near shore or cut straight 

across the canyon. Killer Whale predation events occurred most often on the north side of Bay 

and began over the deep canyon before the Gray Whales reached shelf waters on the north 

side of the Bay. The killer whales often chased the Grays further north or east into shelf 

waters. 

W. Perryman (NMFS) conducted surveys of Gray Whale calves from 1994 to 2002 

from a shore station south of Monterey. The number of Gray Whale calves born each year 

varied from a peak of 501 calves counted on survey to a low of 87 calves. In years with high 

Gray Whale calf counts there were more attacks by Killer Whales in Monterey Bay. During 

1999, the first year of low calf numbers, there were many Killer Whale sightings over the 

spring migration months but Killer Whales were not finding calves. Even so there were three 

known attacks, possibly due to the continued presence of Killer Whales in the area. 

The steep bathymetry of the canyon edge seemed to provide some advantage to the 

Killer Whales and provoked a radical change in surfacing and travel behavior in the Gray 

Whales. Passive listening by Killer Whales and possible orienting vocalizations near canyon 

edges by the Gray Whales may serve to increase vulnerability. There is also the possibility 

that communication occurs between the Gray Whale mother and calf, or the calf is 

inappropriately vocalizing. The Killer Whales seemed to use the Bay as a prime hunting zone 

and may form small groups of 5-10 individuals to converge on the location of a mother/calf 

within minutes to hours of their detection. 



157

Once a mother/calf Gray Whale pair was detected, the Killer Whales grouped up and 

pursued them until the Grays slowed down and were surrounded by the Killer Whales. As 

much as six hours may pass from initial attack to kill with ramming, biting, pulling on the 

pectoral fins, and attempts to separate the mother from the calf. During this period the mother 

and calf try to dash for the safety of shallow water and the mother Gray will often roll belly 

up and her calf will get on top of her for brief periods of safety from the intense onslaught. If 

the Killer Whales are successful in driving away the mother, the calf is swiftly drowned and 

feeding commences. The protracted struggle involves female Killer Whales, juveniles, and 

calves. Adult males appear to be able to kill successfully on their own but as a male team of 

two, they also will participate in feeding events resulting from the attack and kill of a Gray 

from cooperating females. 

The amounts of the carcasses that the whales fed on ranged from just the tongue and 

blubber around the lower jaw to extensive feeding with complete stripping of the blubber. The 

tongue weighs as much as 400 Kg and the blubber over several thousand Kg. Sometimes the 

force exerted by the Killer Whales was enough to decapitate a calf. 

Even though nearly the entire transient population sighted off Monterey Bay has been 

present during a Gray Whale attack, they were not all directly involved. In over 60% of welldocumented 

attacks, three core groups of whales that were frequently sighted in the study area 

were present. Adult reproductive females within these core groups worked together and 

engaged in specific roles; for example, one whale acted as separator between the Gray Whale 

mother and calf and others assisted around the periphery of the Grays to overcome the calf. 

The ecosystem found off Central California provides a diverse prey base available to 

Killer Whales and mastery of a variety of hunting techniques by the whales is essential. This 

applies to both temporal and spatial distribution of a food resource. This implies that a young 

Killer Whale needs an extended period of instruction, such as locating key areas at the correct 

time of year, determining suitable hunting habitat, overcoming prey items of vastly different 

sizes, working within a group cooperatively, and absorbing cultural nuance from other group 

members. 

California Sea Lion 

Gray Whale Calf 

Dall's Porpoise 

Elephant Seal 

Seabird 

Harbor Seal 

Pacific White-Sided Dolphin 

Common Dolphin (Dc) 

0 10 20 

Percent 

30 40 

Fig 1. Proportion of prey items observed. 



158

percent number of sightings 

16 

14 

12 

10 

8 

6 

4 

2 

0 

 

 

 

 

 

 

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 

 

 

month (1987-2001) 

Fig. 2 Percent number of sightings of Killer Whales by month. 

Key Whales Involved in Gray Whale Attacks 

Adult Females 

All whales with 1 or more calves 

Adult Males 

Work in pairs 

Whale # 39 40 49 50 51 24 25 30 

Attack Date* Group Size 

4/27/92 X X 

2 

5/2/92 X X X X X 

18 

5/15/93 X X X X X 

20 

4/11/97 X X X X 

30 

4/21/97 14 

4/19/98(1) X X X X X 

12 

4/19/98(2) X X 2 

5/24/99 X X 

11 

6/5/99 X X X X 

20 

*only dates for best observations and some or all IDs 

Table 1. Key killer whales (by ID #) involved 

in 60% of attacks on Gray Whales. 



 

 

 

 

159

WHISTLES AND VARIABLE CALLS AS CLOSE-RANGE ACOUSTIC SIGNALS IN 

WILD KILLER WHALES OFF VANCOUVER ISLAND, BRITISH COLUMBIA 

Thomsen F. 1 , Teichert S. 1 , Riesch R. 1 , Rehn N. 1 , Ford J. K.B. 2 

1 Zoologisches Institut und Zoologisches Museum, Arbeitsbereich Ethologie, Martin-Luther-King-Platz 

3, D-20146 Hamburg, Germany,thomsen@zoologie.uni-hamburg.de; 

2 Marine Mammal Resarch Program, Pacific-Biological-Station, Nanaimo, Fisheries and Oceans, 

Canada, B.C. Canada V9R 5K6. 

INTRODUCTION 

In a variety of terrestrial social mammals sounds used in close-range signalling are 

graded. Graded sounds are highly variable with fluid transitions between basic signal 

types. The complexity or intensity of the graded sound correlates closely with the arousal 

level of the signaller, facilitating a subtle information transfer between interacting 

individuals ( Marler 1976; Fox and Cohen 1977; Zimen 1978; Goodall 1986). Further, in 

mammals and birds, close-range sounds follow a ‘motivation-structural-code’, where high 

pitched tonal sounds signal friendly motivations and low frequency broad-band sounds 

signal agonistic ones (Owings and Morton 1998). Most delphinids emit a great variety of 

whistles and burst-pulses during close-range interactions (review in Herzing 2000). 

However, only limited attempts have been made in a detailed behavioural and structural 

analysis of those signals. Therefore close-range acoustic communication in delphinids is 

only poorly understood. 

Resident killer whales (Orcinus orca) off the coast of British Columbia produce 

whistles and variable pulsed calls at high rates during close-ranges, for example during 

socializing (Ford 1989; Thomsen et al. 2002). Earlier studies indicate that variable calls are 

graded and that both sound types are used to signal motivation during close-range 

interactions (Ford 1989). However, no study has focussed on a detailed analysis of the 

structure of whistles and variable calls. Our ongoing and long-term study investigates in 

the structure of whistles and variable calls in northern resident killer whales off British 

Columbia. 

METHODS 

Since 1994 we collect underwater sound recordings and surface behavioural 

observations of northern resident killer whales in Johnstone Strait and adjacent waters. We 



160

also analyse earlier recordings obtained between 1978-1983 by one of us (J.K.B. Ford). 

We use SIGNAL, version 3.0, and RTS, version 2.0 (Engineering Design), for 

bioacoustical analysis. For a detailed description of data collection- and analysis see 

Thomsen et al. (2001, 2002). 

RESULTS 

Whistles are physically diverse signals with the majority being harmonical sounds. 

Parameter measurements indicate that they are very complex: they range in duration 

between 0.06 and 18 s (average 1.8 s) and contain between 0 and 71 frequency 

modulations (Thomsen et al. 2001). Our observations in the field indicate that they have a 

relatively short range of detectability (< 500 m). This corresponds closely with Millers 

(2000) findings, who measured an average ‘soft’ source level of 140 dB re 1µPa at 1 m 

(range 129-148 dB) for whistles of northern resident killer whales. About 25 % of all 

whistles appear to be stereotyped and stable for almost two decades (Fig. 1). We found six 

stereotyped whistles forms (W1-W6) that are often emitted in sequences (Fig. 2). In a 

sequence stereotyped whistles of the same type follow more frequently each other than 

different types. 

On the other hand, we could confirm that variable calls are structurally graded 

sounds. Teichert (2000) found variable call types that differed in carrier frequencies. These 

call types can be arranged on a graded scale from very low-frequency calls to high 

frequency ones. 

DISCUSSION 

We conclude that both whistles and variable calls play a very important role in 

coordinating close-range interactions in wild killer whales. It is possible that variable 

whistles indicate the motivation directly through the duration and number of frequency 

modulations. Stereotyped whistles are evidently used for close-range signalling too and we 

suspect that sequences of stereotyped whistles play an important role here. Sequences 

could indicate motivation over time with long and complex sequences indicating a higher 

motivation of the sender (s) than shorter and simple ones. Thus, sequences might be of 

great importance in coordinating and maintaining interactions at close-ranges. The results 

on variable calls further support earlier observations that variable calls in wild killer 

whales are organised similar to graded calls in canids and primates. The different forms of 

variable calls probably indicate subtle variations in motivation in accordance to 



161

motivation-structural-rules. Then, low frequency calls would signal agonistic motivations, 

whereas high-frequency types signal friendly ones. 


We would like to thank Jim Borrowman and Bill and Donna Mackay for their support 

for this study. Thanks to Dave Tyre, Brian Sylvester, Wayne Garton, Rolf Hicker and Steve 

Wischniowski for their help in the field. Dave Briggs, Helena Symonds, Paul Spong, Rob 

Williams and Anna Spong provided important information on whale locations. Many thanks 

to Prof. Dr. Andreas Elepfandt and Dr. Karl-Heinz Frommolt (Humboldt-University, Berlin) 

for their cooperation. F. Thomsen would like to thank Jakob Parzefall, Cord Crasselt, Ralf 

Wanker, Massoud Yasseri and Ingo Schlupp for their help during the analysis at Hamburg 

University. We thank Christina Jakisch, Simone Hinzpeter, Stephanie Stempell, Rouven 

Schmidt and Stefan Froschauer for their help in whistle classification. The study was partly 

funded by a graduate scholarship of the University of Hamburg and by a scholarship of the 

German Academic Exchange Fund (Bonn). 

REFERENCES 

Ford, J.K.B. (1989). Acoustic behaviour of resident killer whales (Orcinus orca) off 

Vancouver Island, British Columbia. Can. J. Zool., 67: 727-745. 

Fox, M.W. and Cohen, J.A. (1977). Canid communication. In: Sebeok, T.A. (ed.), How 

animals communicate. Indiana University Press, Bloomington, London, pp. 729-747. 

Goodall, J. (1986). The chimpanzees of Gombe. Patterns of behavior. The Belknap 

Press of Harvard University Press, Cambridge. 

Herzing, D. (2000). Acoustics and social behavior of wild dolphins: implications for a 

sound society. In: Au, W.W.L., Popper, A.N. and Fay, R.R. (ed.) Hearing by whales and 

dolphins. Springer, pp. 225-273. 

Miller, P.J.O. (2000). Maintaining contact: design and use of acoustic signals in killer 

whales, Orcinus orca. Ph.D. dissertation. Massachusetts Institute of Technology, Woods Hole 

Oceanographic Institution. 

Marler, P. (1976). Social organization, communication and graded signals: the 

chimpanzee and the gorilla. In: Bateson, P.P.G. and Hinde, R.A. (ed.), Growing points in 

ethology. Cambridge University Press, Cambridge, pp. 239-280. 

Owings, H.O. and Morton, E.S. (1998). Animal vocal communication: a new approach. 

Cambridge University Press, Cambridge. 



162

Thomsen, F., Franck, D. and Ford, J.K.B. (2001). Characteristics of whistles from the 

acoustic repertoire of resident killer whales (Orcinus orca) off Vancouver Island, British 

Columbia. J. Acoust. Soc. Am. 109: 1240-1246. 

Thomsen, F., Franck, D. and Ford, J.K.B. (2002). On the communicative significance of 

whistles in wild killer whales (Orcinus orca). Naturwissenschaften 89: 404-407. 

74. 

Zimen, E. (1978). Der Wolf. Mythos und Verhalten. Meyster, Wien, München, pp. 35- 

Fig. 1 Exemplary spectrograms of whistle types W1-W3 recorded in different years (DT = 20.5 ms, DF = 48.8 

Hz, FFT size = 1024 points). Above: W1 1983, 1996, 1997; mid: W2 1979, 1996, 1997; below: W3 1979, 1996 



163

Fig. 2 Spectrograms of three sequences of stereotyped whistles recorded from socializing killer whales Above: 

A5, D1 1980; mid: A1 1996; below A1, A5 1997. (DT = 20.5 ms, DF = 48.8 Hz, FFT size = 1024 points). 



164

A REVIEW OF SHORT- AND LONG-TERM EFFECTS OF WHALE WATCHING 

ON KILLER WHALES IN BRITISH COLUMBIA 

Andrew W. Trites 1 , David E. Bain 2 , Robert M. Williams 1 & John K.B. Ford 1,3 

1.Marine Mammal Research Unit, Fisheries Centre, University of British Columbia, Vancouver, BC 

2. Friday Harbor Labs, University of Washington, Friday Harbor, WA 98250 

3. Marine Mammal Research Program, Pacific Biological Station, Fisheries & Oceans Canada, 

Nanaimo, BC 

INTRODUCTION 

Whale watching is often promoted as an alternative to whaling or fishing. It is a 

growing industry around the world and one that raises questions about its effects on marine 

mammals. In particular—can the whales sustain it? This is the fundamental question we 

explored. 

In British Columbia, killer whales have been studied for 25 years, and watched 

commercially and recreationally for about 20 years. They seem to receive more attention than 

any other species of cetacean. 

Of the three populations of killer whales in British Columbia, it is the residents that are 

the focus of whale watching. The two core areas for commercial whale watching are Haro 

Strait and Johnstone Strait. Most of the studies of the effects of whale watching on killer 

whales have been conducted in Johnstone Strait. 

For the past 7 years, numbers of killer whales in the northern resident population have 

been relatively stable, while those in the southern residents have declined. Some have argued 

that whale watching has contributed to this population decline. 

There has been a sharp increase in the numbers of commercial boats engaged in whale 

watching in Haro Strait, while those in the northern region have remained stable. There has 

also undoubtedly been a significant growth in numbers of private boats engaged in watching 

the whales. 

SHORT TERM EFFECTS 

The first studies of the effects of whale watching began in the 1980s when David Briggs 

watched the response to killer whales to vessels at the rubbing beaches of Robson Bight in 

Johnstone Strait. At about the same time, Susan Kruze observed the whales form a cliff 

across from the Bight, while David Duffus and Nicole Adimey made observations from the 

water. 

Their findings can be essentially summarized under two categories of responses: ‘near 

shore’ and ‘away from shore’. 

David Briggs found that whales stopped rubbing when approached by boats, while 

Susan Kruse reported that whales swam 1.5 times faster when boats were present. David 

Duffus was unable to note any affect, while Nicole Adimey noted a change in behavior— 

killer whales were 3-4 times more percussive when a single boat was present, but showed no 

apparent response when more than one boat was present. 

During the 1990s, researchers had a new tool to further their understanding of the 

effects of whale watching on killer whales. It was the Killer Whale Catalogue, which enabled 

them to identify the response of known individuals. There were also large numbers of 

volunteers prepared to put in thousands of hours of observation. 



165

BC Parks established an ecological reserve at Robson Bight to protect the killer whale 

rubbing beaches. It is a reserve that works on the honor’s system, whereby boaters are asked 

to voluntarily restrain from entering the reserve. Observations made in the 1990s from the 

cliff across from the Reserve noted numbers of vessels and whales that were inside and 

outside of the Reserve. Analyzing these thousands of observations showed that killer whales 

left or stopped rubbing when boats were present. They also showed that the probability of 

leaving increased with an increase in the number of vessels that entered the reserve. 

One of the problems with all of the analyses done up to this point was that there were no 

real controls and the studies relied on opportunistic observations. This lead to Rob Williams 

conducting an experiment to track a single whale when no boat was present, then to have an 

experimental boat approach and follow the same individual according to accepted whale 

watching guidelines. Observations were made using a theotolite, a spotting scope and a 

laptop computer from the cliff top. 

The data collected during this experiment allowed the X-Y coordinates of where whales 

surfaced to be determined. From this, the angle of deviation and the overall directness of 

swimming were calculated. Thus the diving and swimming behavior of whales was compared 

before and after a boat was present. 

In the presence of one boat, Williams found that females swam faster, and had greater 

angles between their dives, than did males. Males on the other hand swam in a less direct 

path. However, when more than one boat was present, females made longer dives and swam 

in a more predictable direction. Males also swam in a more predictable direction, but at 

slower speeds. 

In summary, short-term immediate effects of whale watching were clearly 

demonstrated. They showed that killer whales are particularly sensitive to vessels when close 

to shore; and that males and females use different strategies in response to the presence of 

vessels when they are away from shore. And finally, they showed that the number and 

proximity of vessels alters their response. 

LONG TERM EFFECTS 

While short-term responses do occur, the question that remains is “so what”? Are there 

any long-term effects? Has anything been detected after 25 years of research? 

One can postulate that whale watching might increase mortality, or reduce birth rates, or 

change the distribution of killer whales. But the reality is that there is no direct evidence that 

such changes can be attributed to whale watching, despite 25 years of research and 20 years of 

whale watching. However, just because such effects have not been measured, does not mean 

that they are not occurring. 

One means of trying to actively evaluate the possible long-term effects of whale 

watching is to compare changes in killer whales over time and space such as whether the 

dynamics and life tables of populations exposed to different levels of whale watching differ, 

or whether populations have different physiological and behavioral responses by region or 

time of year. Another approach is to develop mathematical models to predict the population 

effects of vessels on hearing and energetics. Such models can show that it is theoretically 

possible for whale watching to have population effects on killer whales. 

CONCLUSIONS 

In conclusion, it is apparent that on a short-time scale, whales employ a multivariate 

array of responses that are a function of vessel numbers, proximity and distance to shore, and 

no doubt numerous other factors. However, on a long-time scale, we can only postulate 

possible effects and may never be able to conclusively demonstrate them. This begs the 



166

question of whether whale watching activities should be curtailed if there is no absolute proof 

that it has a negative long-term effect on killer whales. 

It is debatable whether such long-term effects should be conclusively demonstrated 

when simply reducing the short-term effects may ultimately reduce the likelihood or severity 

of long-term effects. A number of approaches might be taken. The first is what is being tried 

in many places – namely to educate the mariner. Another is to establish whale reserves where 

boats do not enter. Thought should also be given to temporal restrictions that reduce the 

number of days that whales are actively pursued by vessels engaged in active whale watching. 



167

ASSOCIATIONS AND GROUP SIZE OF KILLER WHALES IN KVÆFJORD, 

INTRODUCTION: 

NORWAY, DURING OCTOBER-NOVEMBER 1997 

Fernando Ugarte 

Whale Works. Allégade 23B 3.th, 2000 Frederiksberg, Denmark. 

Photo identification of killer whales in the coastal waters of northern Norway during 

October-November has taken place since 1983 (Lyrholm 1988, Similä and Ugarte 1997). 

During this time of the year, a large number of killer whales follow the migration of the 

Norwegian spring-spawning herring stock, which normally winters in the waters of Vestfjord 

and its tributary fjords, including Tysfjord (Similä et al 1996). During 1997-1998, part of the 

Norwegian spring-spawning herring stock wintered in the area of Kvæfjord, Norway, and 

some killer whales followed (fig.1). This atypical wintering area contained an aggregation of 

killer whales smaller than the one normally found in Vestfjord. 

Photo identification fieldwork in Kvæfjord yielded more within-season re-sightings than 

the usual fieldwork in Vestfjord. The present study examines the associations of the killer 

whales observed in Kvæfjord, to complement the previously suggested model of social 

relationships of the Norwegian killer whales (Similä and Ugarte 1997). 

METHODS: 

Observations were made between October 25 and November 14, 1997, from a 10 m 

cabin cruiser. Once a killer whale group was localised, the first 10 minutes of the encounter 

were used to observe from a distance and record group size and group activity. After the 

observation period, the whales were photographically identified. An encounter ended when it 

was believed that all the whales with conspicuous marks had been photographed. In order to 

avoid bias due to repeated samplings of the same situation, each consecutive encounter was 

made either on a different group or during a different group activity. 

When there were several groups in the area, a killer whale group was defined as a 

cluster of animals that appeared to be independent from others. When a group was divided in 

clear sub-groups, special emphasis was made in observing the behaviour and counting the 

number of individuals in the sub-group that was closer to the boat during the 10 minutes 

observation period. 

Individual whales were identified from photographs of their left side showing the dorsal 

fin and saddle patch (Bigg et al 1987). Each identified whale received an individual 

alphanumerical code. Pictures of the identified whales were compared with identification 

pictures of killer whales in northern Norway taken during 1983-1996 (Similä, unpublished 

catalogue). 

A cluster analysis was made in order to investigate the existence of groups formed by 

whales with strong associations. The analysis was made using Cystat © 7.0.1 software, with 

average linkage method and Euclidean distances from a matrix containing the association 



168

values of all possible pairs of whales. Simple ratio indexes of associations were used (Wilson 

1995). Only the whales observed more than once were included in the analysis. 

RESULTS: 

Killer whales were observed during 11 days (n = 60 encounters). Photo identification 

efforts were done during 36 encounters and 56 whales were identified, of which 14 (25%) 

were seen in Tysfjord during 1990-1993. 

There were no relationships between killer whale group size and activity state. 25% of 

the groups were divided into two or more sub-groups (n = 60 group counts). Group sizes 

ranged 1-25 individuals (median = 8 individuals) and sub-groups ranged 1-18 (median = 6 

individuals). 

The size of whole groups changed only twice during the 600 minutes of observations, 

which corresponded to one occasion in which one whale left and one in which one joined a 

group. Re-arrangements of the constellations of whales within a group were more frequent. 

The number of subgroups within the group changed 4 times and whales switched from one 

subgroup to another 11 times (n = 600 minutes). 

63 % of the animals (n = 35 individuals) were identified during more than one 

encounter. On only 7 occasions killer whale individuals were observed two consecutive times 

in groups of the same size (n = 87 successive values for group size of known individuals). 

This lack of stability in the group size is illustrated by the group sizes of NE1, the whale 

identified more times during this study (n = 11 observations). The group sizes of NE1, in the 

order observed, were: 11, 7, 12, 1, 7, 20, 9, 8, 15, 10 and 25 whales. 

An average of 60 % of the whales present were identified on each encounter (n = 36 

encounters, SD 27). The cluster analysis showed 10 groups of whales with association 

distances closer than 0.5, suggesting strong bonds between individuals (fig. 2). Some of the 

animals that showed the strongest associations had also been identified together in previous 

years (table 1). 

DISCUSSION: 

The fact that not all the animals present in each group were always identified can have 

caused underestimations of association indexes. Despite this problem, several whales showed 

high probabilities of being identified together. Some of the animals that showed strong 

associations have also been identified together in previous years, indicating that Norwegian 

killer whales associate with the same partners during time scales of few weeks and during tens 

of years. Long-term associations do not seem to depend on the sex of the animal, since males 

associated with males, males with females and females with females. Similä and Ugarte 

(1997) showed that males identified as juveniles in the 1980s continued to swim close to their 

mothers after reaching sexual maturity in the 1990s, suggesting that Norwegian killer whales 

form stable matrilineal groups. All these results indicate that killer whales in Norway do form 

very stable bonds. 

Advantages of living in stable matrilineal groups include: learned behaviour and 

information can be transmitted by more experienced whales to genetically related animals 

(Boran and Hemlich 1999); by cooperatively foraging with kin, food sharing and provisioning 

can increase fitness (Dawkins 1976); animals that know each other well can coordinate the 



169

search and hunt better and increase the per-capita rate of food consumption (Heishorn and 

Packer 1995); allomaternal care (Woodroffe and Vincent 1994). 

Despite the potential advantages of living among close kin, matrilineal groups where 

males remain after reaching sexual maturity are very rare among animals. This may be due to 

the difficulty of avoiding inbreeding. Killer whales may get around this problem if females 

are able to decide whom to mate with after assessing the genetic proximity of potential 

partners with the help of vocal dialects (Barret-Lennard 2000). 

During this study, killer whale groups were sometimes arranged into subgroups in 

constellations that changed either because the subgroups split or joined or because individuals 

moved between subgroups. Group sizes changed seldom during an observation period, while 

individuals typically formed part of groups of different size during two consecutive 

observations. These results suggest that the whales within a group rearranged positions within 

minutes and that group sizes are stable during few hours and change after several hours. 

The existence of individuals with strong bonds and groups of flexible size could be 

explained if Norwegian killer whales were socially organised in small, stable units that split 

and join with similar units. Such units could be equivalent to the matrilineal units described 

for the resident killer whales in the west coast of North America (Bigg et al 1987). 

The searching efficiency of killer whales as predators depends on factors such as their 

ability to echolocate and / or to find prey by listening, either to the prey itself or to the sound 

of other predators feeding (Barret-Lennard et al 1996). Large groups can spread and search in 

larger areas, while it may be easier to coordinate activities in small groups. In Norway, killer 

whale group size may be an adaptation to the abundance of suitable herring schools, with 

larger groups being better when such schools are scarce. The existence of foraging groups that 

change size according to the density of food patches has been described for several species 

(Chapman et al 1995). A social organisation as described above, composed of small, stable 

groups that split and join, would be ideal to achieve group sizes that fit the density of suitable 

herring schools, while at the same time keeping the advantages of having at least some stable 

companions. 

ACKNOWLEDGEMENTS: 

Funding was provided by NFH (Tromsø University),WWF Sweden and ANCRU. Tiu 

Similä and Tore Haug gave essential advice. Ben Wilson, Peter Van der Gullik and Volker 

Ratmeyer helped in the field. Godstrek made the figures. Tiu Similä allowed access to the 

sighting histories of whales identified during 1988-1993. 

REFERENCES: 

Barret-Lennard, L. 2000. Population Structure and mating patterns of killer whales 

(Orcinus orca) as revealed by DNA analysis. PhD thesis. University of British Columbia 

Barret-Lennard, L., Ford, J.K.B. and Heise, K. 1996. The mixed blessing of 

echolocation: differences in sonar use by fish-eating and mammal-eating killer whales. Anim. 

Behav. 51:533-565 



170

Bigg, M.A, Ellis, G.M., Ford J.K.B. and Balcomb, K.C. 1987. Killer whales, a study of 

their identification, genealogy and natural history in British Columbia and Washington State. 

Phantom Press and Publishers Inc. Nanaimo, B.C. 

Boran J.R., and Hemlich S.L. 1999. Social learning in cetaceans: hunting, hearing and 

hierarchies. In: Mammalian Social Learning. Ed: Box, H.O. and Gibson, K.R. Cambridge 

Univ. press: 282-307 

Chapman, C.A., Wrangham, R.W. and Chapman, L.J. 1995. Ecological constraints on 

group size: an analysis of spider monkey and chimpanzee subgroups. Behav. Ecol. Sociobiol. 

36:59-70 

Dawkins, R. 1976. The Selfish Gene. Oxford Univ. Press, Oxford. 

Heishorn, R., and Packer, C. 1995. Complex cooperative strategies in group territorial 

African lions. Science. 269(5228): 1260-1262. 

Lyrholm, T. 1988. Photoidentification of individual killer whales, Orcinus orca, off the 

coast of Norway, 1983-1986. Rit. Fiskideildar. 11:89-94. 

Similä T. and Ugarte F. 1997. Social organisation of north Norwegian killer whales. In: 

Similä, T. PhD thesis. NFH, University of Tromsø 

Similä, T., Holst, J.C., and Christensen, I. 1996. Occurrence and diet of killer whales in 

Northern Norway: seasonal patterns relative to the distribution and abundance of Norwegian 

spring-spawning herring. Can. J. Fish. Aquat. Sci. 53:769-779 

Woodrofe, R. and Vincent, A. 1994. Mother's little helpers: patterns of male care in 

mammals. Trends Ecol. Evol. 9:294-297 

Wilson, D.R.B. 1995. The ecology of bottlenose dolphins in the Morray Firth, Scotland: 

a population at the northern extreme of the species range. PhD thesis. University of Aberdeen. 



171

Table 1. Whales seen together in the same group during this study, during the period 1983-1986 (Lyrholm 1998) 

and during 1988-1993 (dataset from Similä and Ugarte 1997). Alphanumerical codes (e.g.: NB-6, NG-22) are 

names assigned to identified individuals. In parentheses are the sex of the whale and the number of times it has 

been seen in all three studies, m = male; f = female. 

Figure 1. Map of the study area 



172

Figure 2. Cluster tree of associations of whales seen twice or more during this study. Alphanumerical codes (e.g.: 

NP9, NG29, etc.) are identification numbers of individual killer whales. Potential groups of whales with strong 

associations are highlighted. 



173

NORWEGIAN KILLER WHALES FEED ON SMALL HERRING SCHOOLS CLOSE 

TO THE SURFACE 

Ugarte F. 

Whale Works Allégade 23 B, 3.th. 2000 Frederiksberg. Denmark, fernando_ugarte@hotmail.com 

INTRODUCTION 

Herring is a physostomus fish and can perform rapid vertical movements, which are 

useful to avoid predators and to undergo diurnal vertical migrations (Blaxter 1985). In its 

wintering area, the herring of the Norwegian spring spawning stock is typically found at 

depths of 0 - 70 meters during night and 150 - 500 meters during daytime (Dommasnes et al 

1994). 

The majority of Norwegian killer whales are predators specialised on herring of the 

Norwegian spring-spawning stock (Similä et al 1996). Although killer whales can dive at 

depths larger than 350 meters, they seem to spend by far most of their time in the upper 20 

meters of the water column (Baird et al. 1998, Schorr et al 2001, Similä et al 2002). The 

deepest interaction recorded between killer whales and herring so far was at a depth of 170 

meters, close to the upper range where herring is typically found during daylight. During 

several occasions, Norwegian killer whales have been observed feeding in the upper 20 

meters of the water column (Similä and Ugarte 1993, Similä 1998, Nøttestad and Similä 

2001). 

Herring have a strong schooling habit that can be used as a defence against predators 

(Magurran 1990, Parrish 1992). Most of the reported observations of Norwegian killer whales 

preying on herring involved small herring schools, rather than the more typical large herring 

aggregations (Similä and Ugarte 1993, Similä 1998, Nøttestad and Axelsen 1999, Nøttestad 

and Similä 2001). 

Killer whales seem to prefer feeding on small herring schools at shallow depths and 

therefore the depth and size of the herring schools may be important factors influencing the 

availability of this fish as a prey item. The present study investigated the relationship between 

the depth and size of herring aggregations and the activity of Norwegian killer whales. 

METHODS: 

The present study was made during October and November of 1997 in the waters off 

Vestfjord, Andfjord, and some of their tributary fjords. 

A fish finder (Simrad Skiper 603) was used to take echo-sounder samples directly 

under killer whales (fig. 1). The herring aggregations were categorised as either schools or 

layers. Layers are shoals with a thickness of about 10 meters and several hundred meters of 

diameter. Previous to the samples, it was recorded whether the killer whales were engaged in 

one of the following activities: Feeding, Travelling, Resting, Socialising (Similä 1997, Ugarte 

2001). Night observations were made using night vision goggles. 



174

RESULTS: 

A total of 55 echo-sounder traces under killer whales were obtained: 46 during daylight 

and 9 during night. 

During daytime and in the absence of killer whales, herring were typically found as 

layers deeper than 150 m. At nightfall, the herring layers ascended to the surface and the killer 

whales abandoned the area. 

During daytime, the herring under the killer whales was at depths of either 0-15 meters 

(n = 16 observations) or more than 50 meters (n = 20 observations). 

During daylight, herring layers beneath killer whales were often at depths larger than 60 

meters, while herring schools were at depths of either 0 - 15 or 60 - 200 meters. 

All feeding observations (n= 13) were made during daylight and involved small schools 

at depths shallower than 15 m (fig. 2). 

DISCUSSION: 

This study supports the idea that killer whales prefer to feed close to the surface (Similä 

and Ugarte 1993, Similä 1998, Nøttestad and Similä 2001). 

The lack of herring observed at 15-50 meters of depth can be explained if all herring 

shallower than 50 m was herded to the surface by the whales. 

Killer whales must be extremely efficient at driving small schools of herring to the 

surface, since no intermediate states between such schools and the typical deep herring layer 

were observed. 

The killer whales may have avoided the herring at night because the sheer amounts of 

fish presented an obstacle for efficient hunting. However, a larger sample would be needed to 

draw clear concussions. 

ACKNOWLEDGEMENTS: 

Funding was provided by WWF Sweden, The Andenes Cetacean Research Unit, The 

Royal International Whale Safari Club. The Roald Amundsen Centre, The Columbus Zoo and 

Pilkington Optronics. This work was part of an MSc for the Norwegian College of Fisheries 

Science, University of Tromsø. Supervisors were Tiu Similä and Tore Haug. Ben Wilson 

provided ideas for this study and helped during fieldwork. Peter Van der Gullik and Volker 

Ratmeyer also helped in the field. Godstrek made the figures. 

REFERENCES: 

Baird, R.W., Dill, L.M. and Hanson, M.B. 1988. Diving behaviour of killer whales. In: 

abstracts of the World Marine Mammal Science Conference. Monaco, 20-24 Jan. The Society 

for Marine Mammalogy and the European Cetacean Society. 

Blaxter, J.H.S. 1985. The herring: a successful species? Can. J. Fish. Aquat. Sci. 

42(1):1-30 



175

Dommasnes, A., Rey, F. and Røttingen, I. 1994. Reduced oxygen concentration in 

herring wintering areas. ICES J. Mar. Sci. 51:63-69 

Magurran, A. 1990. The adaptative significance of schooling as an anti-predator defence 

in fish. Ann. Zool. Fennici. 27:5-66 

Nøttestad, L. and Axelsen, B.E. 1999. Herring schooling manoeuvres in response to 

killer whale attack. Can. J. Zool. 68:1209-1215 

Nøttestad, L., and Similä, T. 2001. Killer whales attacking schooling fish: why force 

herring from deep water to the surface? Mar. Mamm. Sci. 17(2):343-352 

Parrish, J. 1992. Do predators "shape" fish schools? Interactions between predators and 

their schooling prey. Neth. J. Zool. 42 82-3):358-370 

Similä, T. 1997. Behaviour and habitat use of killer whales in northern Norway. In: 

Simila, T. PhD thesis. NFH, University of Tromsø 

Simila, T. 1998. Sonar observations f killer whales feeding on herring schools. Aq. 

Mam. 23(3):119-126 

Similä T., and Ugarte F. 1993. Surface and underwater observations of cooperatively 

feeding killer whales (Orcinus orca) in northern Norway. Can. J. Zool. 71:1494-1499 

Similä, T., Holst, J.C. and Christensen, I. 1996. Occurrence and diet of killer whales in 

northern Norway: seasonal patterns relative to the distribution and abundance of Norwegian 

spring-spawning herring. Can. J. Fish. Aquat. Sci. 53:769-779 

Similä, T., Holst, J.C., Øien, N., and Hanson, B. 2002. Satellite tracking study of 

movements, range and diving behaviour of killer whales in the Norwegian Sea. In: abstracts 

of the 16th annual conference of the European Cetacean Society, Liege. Pp. 18-19 

Schorr, J.L., Baird, R.W., Foster, J.F. and Hanson, M.B. 2001. Diving behaviour of 

fish-eating killer whales off Southern Iceland. In: abstracts of the 14 th biennial conference on 

the biology of marine mammals. Victoria. 

Ugarte, F. 2001. Behaviour and social organisation of killer whales in northern 

Norway. MSc thesis. NFH, University of Tromsø. 



176

Figure texts for the summary of: "Norwegian killer whales feed on small herring 

schools close to the surface", by Fernando Ugarte: 

Figure 1: Trajectories of the boat while taking echosounder samples. The goal was to minimise the risk of 

missing small herring schools among the whales. A) When the whales moved forward, the boat sampled close 

behind the group. B) When the whales remained in the same area, the boat sampled through the group. 

Figure 2: Killer whale activity state and: herring depth (top); type of herring aggregation (bottom). N = 45 

encounters. 



177

CAN ROUTINE DATA COLLECTION BENEFIT KILLER WHALE RESEARCH? 

INTRODUCTION 

A.M. van Ginneken, KC Balcomb III 

Center for Whale Research, Friday Harbor, Washington, U.S.A. 

Research data are ideally collected prospectively in a controlled setting, but killer 

whales cannot be controlled. In addition, public pressure makes observation and data 

collection increasingly difficult, even more so in the context of a specific research question. 

Another frequent problem is lack of ‘control’ data: when a research question arises because of 

a subjectively observed change or trend, one can no longer measure the past. A longterm 

collection of data on a routine basis may provide control data for the future, and may reveal 

relationships between parameters of orca life and human impact that can only be detected 

with large amounts of data collected in a variety of circumstances. 

Researchers, however, who attempt to analyze routinely collected data retrospectively, 

are often confronted with limitations due to incompleteness and lack of standardization. 

Photo-ID is a well established method that has produced many years of analyzable data. 

Behavior is much more elusive to document. The challenge is to get most out of each 

opportunity to observe killer whales as systematically as possible. How systematic can we be 

when we have to work with what the orca and its environment provide? 

This summary adresses the collection, representation, and extraction of data in the 

context of the Orca Survey, an ongoing study on killer whales by the Center for Whale 

Research (CWR) since 1976. Specific emphasis will be on parameters concerning behavior 

and the environment. 

DATA COLLECTION 

Since 1976, the CWR has taken identification photographs, according to the method that 

Mike Bigg established in 1973 [1,2]. The analysis of these photographs have revealed much 

about the population dynamics and association behavior of the Southern resident population 

of orcas [3]. 

Since 1994, we introduced routine collection of data on behavior and environmental 

parameters, such as wind (Beaufort scale), tide, and number of vessels present. In our attempt 

to make the method as systematic as possible, we based it on three main principles: 

1. Recording of observations rather than interpretations 

2. Defining behaviors with a high level of consensus among observers 

3. Explicit recording of detail and lack of detail 

Typical examples of interpretation are behavior terms like ‘foraging’, ‘feeding’, and 

‘play’. Examples of observation terms are: ‘travel medium’, ‘groups spread out’, ‘breach’, 

and ‘taillob’. Data collection based on observations has two advantages: 

One can define criteria for ‘play’ and ‘foraging’ in a more objective way and extract 

more homogeneous sets of data, that fulfill these criteria. With recordings at the interpretation 

level one cannot go back to the source data for the actual observations. 

Consensus about observations is much easier to achieve than consensus on 

interpretations. Recognition of a type of behavior can effectively be trained in a short period 

of time as has been proven among Orca Survey staff and Earthwatch volunteers, who spend 

only 10 days on site. 



178

The Orca Survey staff has accentuated the definitions of behaviors that can be observed 

in the wild. These behaviors are devided in ‘duration’ behaviors that last for a certain period 

of time, and ‘instantaneous’ behaviors that occur in a moment and can be counted. The 

duration behaviors encompass travel speed and travel formation, whereas the instantaneous 

behaviors include the breach, spyhop, taillob, etc.These well-defined behavior types are 

illustrated on a reference tape of orca behaviors, showing fragments of wild footage. The tape 

has been scrutinized by staff and serves as a teaching instrument for volunteers and new staff. 

Behavior is difficult to record: much of what is going on escapes our attention, we often 

cannot visually identify which individual displays a behavior, or name all the members in a 

group, if it were only for the distance we have to the whales. We do not want to pretend 

completeness by entering ‘guesses’ for what we cannot asses. We explicitly record what we 

can and cannot not observe. The core of our records on behavior is: Who did What When. For 

this purpose we show the main fields on our Behavior log form with some data: 

Date: 20-Jun-2002 

Time Id(s) Behavior Number of whales Frequency 

10:20 J2,J30,unk Slow 3 

10:24 unk Breach 1 2 

10:26 unk Taillob 2 5 

Line 1 means: a group of three whales, of which only J2 and J30 can be identified, 

travels slowly. 

Line 2 means: an unknown whale did two breaches in succession. 

Line 3 means: two whales did 5 taillobs, but it was unclear how many each whale did. 

Uncertainty in the recognition of individuals is represented by ‘unknown’, sometimes 

the number of whales is blank, because the number of whales engaged in the behavior cannot 

be assessed. 

Beside behavior, we record GPS coordinates, and every 15 minutes we document the 

seastate on a Beaufort scale, the tide, and the number and type of vessels present. All data are 

recorded under staff supervision on paper forms, which are checked prior to data entry in a 

database, and rechecked by staff after data entry. 

THE DATABASE 

Currently, we have a database with photo-ID data and life-history parameters, such as 

matrilines, gender, and age-estimates. The behavior database contains the parameters 

mentioned above. 



179

Fig. 1 Structure of Orca Survey data in Access, including photographic, behavior, and GPS data. 

The first author designed a relational data model in third normal form, and applied 

extensive referential integrity [4], ensuring that all data are linked via the encounter date, 

encounter sequence, and time of observation. The encounter sequence makes all data unique 

for situations when crew on more than one vessel are simultaneously recording data. The 

main tables and their relationships are shown in Figure 1. 

Data from a handheld GPS is directly loaded into the computer. The GPS data are 

imported in Excel and new attributes are added to represent date and time in proper format for 

the Access database. The Excel data are then imported into Access and linked with the main 

table Boatmain. 

DATA EXTRACTION 

The Access database is the basis for all data extractions through SQL queries. Query 

results can then be used for descriptive graphs and tables of for statistic analysis. In the 

presented poster, we do not focus on the statistical confirmation or rejection of a specific 

scientific hypothesis, but we show examples of data extraction, resulting in data that may be 

subjected to such analysis. The examples of data extraction, as illustrated in the poster, are 

based on query results that have been exported to Excel: 

Population parameters: 

Population size since 1976 

Births and losses since 1976 

Age – gender distribution since 1973 (1973-1975 data from M. Bigg ang G.Ellis) 

Age at delivery in relation to calving order 

Age and gender at death / disappearance 

Matrilines showing gender and age category (illustrating reproductive capacity per pod) 

Behavior: 

Travel speed in relation to number of boats present 



180

Travel formation in relation to number of boats present 

Plot of boattracks in the presence of orcas 

Plot of locations where milling behavior was observed 

For plotting of query results involving GPS data, a conversion of these data for plotting 

in Ozi-explorer was performed with Microsoft Excel, followed by a few simple manipulations 

in Wordpad. 

CONCLUSION 

We showed our methods for data collection, representation, and extraction. Although 

we are aware of the limitations of retrospective research, we believe that longterm collection 

of these data will help to detect changes overtime and may reveal relationships between 

parameters that we have not yet been aware of. 

REFERENCES 

[1] Bigg MA. An assessment of killer whale (Orcinus orca) stocks off Vancouver island, British Columbia. 

Rep. Int. Whal.Comm. 1982;32:655-66. 

[2] Bigg MA, MacAskie IB, Ellis G. Photoidentification of individual killer whales. Whalewatcher 

1983;17(1):3-5. 

[3] van Ginneken AM, Ellifrit DK. Orca Survey All Whale Guide to the Southern Resident Community 1976- 

2000 . Center for Whale Research, Friday Harbor WA. 2000. 

[4] Date C. Introduction to Database Systems. 1995. Addison-Wesley, New York. 

E-mail address of the first author: vanginneken@mi.fgg.eur.nl 



181

PHOTOIDENTIFICATION OF KILLER WHALES IN ICELANDIC WATERS 

Vikingsson, G 1 , Sigurjonsson, J. 1 , Similä, T 2 . 

1 Marine Research Institute, P.O.Box 1390, 121 Reykjavik, Iceland, gisli@hafro.is ; 

2 Wild Idea, P.O.Box 181, 8465 Straumsjøen, Norway 

A long-term photoidentification study of killer whales (Orcinus orca) in Icelandic 

coastal waters was initiated in 1981. The study focuses on occurrence pattern of killer whales, 

stability of associations among the identified whales and possible movements of killer whales 

between Icelandic and Norwegian coastal waters. Herring (Clupea harengus) is apparently the 

main type of prey of killer whales in Icelandic coastal waters and photoidentification work 

has been carried out both in the wintering grounds of Icelandic herring off the east coast of 

Iceland and in the spawning grounds of herring off the south coast of Iceland during summer. 

In 1985-86 dedicated field work was carried out for several months, during other years cruises 

have been of shorter duration or identification pictures have been obtained on a more 

opportunistic basis. 366 killer whales have been identified. Most of the identification data is 

from the wintering grounds of herring but 56 different individuals have been identified in the 

summer spawning grounds of herring. The identification data indicates that at least some of 

the whales exploit herring both at the winter and summer grounds. In addition, two whales 

have been identified from a group of killer whales observed harrassing a grey seal 

(Halichoerus grypus); these whales have not been identified in the herring grounds. The 

opportunistic collection of identification pictures has resulted in relatively few resightings; 

only 25 % of the whales have been sighted during more than one season. This has made the 

analysis of group structure and stability difficult, however, the resighting data shows that 

stable bonds exist between the adult individuals. No matches have been found between the 

Icelandic and Norwegian identification catalogues 



182

NEW ZEALAND ORCA 

Visser I.N. 

Orca Research Trust P.O. Box 1233, Whangarei, New Zealand, ingrid@orca.org.nz 

ABSTRACT. 

Between 1992 – 1997 a study was established to determine baseline information on 

New Zealand orca, and to provide recommendations for future management and conservation. 

Photo identification was used to determine distribution around New Zealand waters and range 

use by individuals. The mean sighting period was 3.8 years. One orca was seen over a 20 

year period, and one resighted 30 times. Fifty orca were resighted five or more times. There 

was an apparent sub-division of the population into at least three geographic sub-populations. 

Association indices were compared within and between the proposed sub-populations as a test 

of possible sub-divisions. The mean associations within the sub-populations were 

significantly greater than between the sub-populations. Preliminary mtDNA analysis supports 

the hypothesis that some New Zealand orca do not mix. Sex ratios for the total population 

and for possible sub-populations do not differ from 1:1. Young are present in all populations, 

although ratios appear to differ. Population estimates show the total New Zealand population 

of orca is at a critically low level (range 65-167 animals, with 115 calculated as alive in 

1997). There was a need to designate a conservation status for New Zealand orca that 

recognised their threats and low population levels. The New Zealand government has 

recently changed their status from ‘common’ to ‘critical’. 

METHODS 

The study area covered the coast of New Zealand out to approximately 20 miles 

offshore and for the purpose of this study, was divided into six Regions. Sighting data of 

individually identifiable animals came exclusively from photographs, not from individuals 

recognised in the field without being photographed. The information from the photo-id 

techniques was used to identify the distribution and range of individual orca and general 

distribution trends for the population. This information was then used to assess if there were 

potential sub-populations, perhaps divided geographically. A simple cumulative total was 

used (Discovery Curve) and calculations for the Total Enumeration (TE) and a stochastic 

model (Jolly-Seber) were both used for estimating the population of New Zealand orca. 

Associations were calculated using the Half-Weight Index. where the higher the Association 

Index (i.e., the closer the number is to 1), the more time the animals spend together. A value 

of zero would indicate that two animals were never seen together. Of the 50 orca seen more 

than five times, 41 had an Association Index of 0.33 or above with at least one other orca. 

These Association Indices were plotted in a graphic ‘circle-plot’, whereby the codes for the 

orca (e.g., NZ1, NZ50) were placed in a circle and lines of different thickness drawn to 

represent the Association Index value. 

RESULTS 

During the period December 1992 - December 1997, 117 individual orca were photoidentified. 

Of these, 75 % (n = 88) were seen on more than two occasions and 42 % (n = 50) 

were seen on more than five occasions. Twelve percent of orca (n = 14) were photo-identified 

on more than 10 occasions, and one orca on 30 occasions. The mean number of sightings for 

the 117 photo-identified animals was 5.4. Other individuals (n = 29) have been seen only 

once. Although some individuals were seen irregularly, others were seen regularly (up to 11 

times per year). The mean number of years over which individuals were sighted was 3.8 



183

years (mode 4, median 8). However, if the 29 animals that were only sighted once were not 

included, the mean number of years over which individuals were sighted rises to 4.7 years 

(mode = 4, median = 8.5). There were three main patterns of distribution of New Zealand 

orca, however, the sighting locations for individual orca varied within each general trend of 

North-Island-only, North+South-Island, South-Island-only. Taking the 50 individuals who 

had been seen more than five times, it was possible to suggest three potential sub-populations. 

Overall, discovery rates were slow, with the maximum number of orca catalogued in 

one year being 37. Using an average orca mortality estimate from overseas of approximately 

2% per year, it is possible to enumerate the population. Considering the longevity of 

individuals and infrequent resightings data, the low frequency of resightings, or even failure 

to resight for up to 12 years, a lack of a resighting may not necessarily predict whether an 

animal was alive or dead in 1997. However, taking all individuals seen in 1997, plus all 

others last seen in previous years (devalued for mortality), a minimum estimate for most of 

the New Zealand orca population was derived for December 1997, (n = 115 orca). For the 

Jolly-Seber population model, the statistical program POPAN-4 was utilised. The size of the 

population in the last six months of 1996 was 119 ± 24 (s.e.) orca (95% confidence intervals 

based on a normal distribution [71, 167]). Of the 117 orca photo-identified, 47 were 

presumed to be females, 35 were confirmed as adult males, 13 were confirmed as SAM’s, two 

were juveniles, 11 were calves and the age or sex class could not be determined for a further 

nine orca. Adding the adult males and SAM’s together gives a sex ratio of 47 females to 50 

males. This sex ratio is not significantly different from a 1:1 sex ratio (X 2 = 0.67, df = 1, p < 

0.5). New Zealand orca tend to travel in small to medium sized groups, where group size 

ranged from two to 22 individuals (mean = 4.5), of which 65% (n = 36) were comprised of 

eleven or less individuals, with groups of 12 (24%, n = 13) being the most common. 

Association Indices were calculated for the 50 orca seen more than five times. The 

highest Association Index value was (0.93), which was calculated for four dyads. The next 

highest Indices (0.84) and (0.83) were calculated for one dyad each, and (0.80) was calculated 

for four dyads. The mean Association Index value (for all 50 orca seen more than five times) 

was 0.25, the mode was 0.13 and the median was 0.18. However, it should be noted that this 

included 857 instances where there was no association at all (i.e., an Association Index of 0). 

Associations within two of the three proposed sub-populations were high. Both the 

‘within North-Island-only’ (NN) and ‘within South-Island-only’ (SS) were significantly 

higher than between the three sub-populations and ‘within North+South-Island’(NS). 

Associations were low between North+South-Island and both the North-Island-only and 

South-Island-only sub-populations. As expected, no associations were recorded between the 

North-Island-only and South-Island-only sub-populations. There was a significant difference 

between the North-Island-only and the North+South-Island sub-populations. In addition, 

there was a significant difference between the South-Island-only sub-population and the 

North+South-Island sub-population. The Association Index within the supposed 

North+South-Island population (NS) was not significantly different to both of the betweenpopulation 

indices (N NS) and (NS S). By limiting the plotted Association Indices to 0.33 

and above (and therefore removing occasional associations), there were a number of distinct 

groupings of orca visible, based on their associations on the circle plots. 

Reclassification of the New Zealand population of orca from the erroneous New 

Zealand governmental category of ‘common’, to the recognised IUCN status of ‘Threatened’ 

or ‘Rare’ was proposed by Visser (2002). Although this would hopefully see more effort put 

into their management, ‘red listing’ the population does not in itself confer protection. 

However, it would impose moral pressure on the New Zealand Government to act 

accordingly. The status has recently been changed within the New Zealand classification 

system to ‘critical’. 



184

Visser, I. N. (2000). Orca (Orcinus orca) in New Zealand waters. Ph. D. Dissertation. 

University of Auckland, Auckland. 



185

PIGMENTATION AS AN INDICATIVE FEATURE FOR POPULATIONS OF 

KILLER WHALES 

Ingrid N. Visser. 

Orca Research Trust, P.O. Box 1233, Whangarei, New Zealand. ; ingrid@orca.org.nz 

ABSTRACT 

Worldwide, the typical diagnostic pigmentation pattern for killer whales (Orcinus orca) 

is a black body with postocular white patches (eye-patches), a white chin and venter 

extending onto a white ventral fluke pattern, and a post-dorsal grey patch (saddle-patch). 

However variations in this basic pigmentation pattern have been observed, beyond the 

infrequently reported albino or ‘white morphs’. These include an overall lighter colouration, 

in some cases lightening to grey, a clearly visible darker ‘dorsal cape’ and dark under-flukes. 

In addition, there appears to be a wide variation in eye-patch size, shape and orientation. 

For instance, in one stranding in New Zealand, all 17 animals had eye-patches less than half 

the size of the typical New Zealand eye-patches. During another encounter with 

approximately 40 animals, similar small-sized eye-patches were apparent, yet the angular 

orientation was different. These 40 animals also showed light to dark grey dorsal 

pigmentation and demarcation of ‘dorsal capes’. On yet another encounter animals were 

noted to have very large eye-patches (approximately three times the size of typical New 

Zealand eye-patches). In over 5000 photographs of New Zealand killer whales, collected both 

opportunistically and historically (from as early as 1915), no other images show these types of 

eye-patches, a dorsal cape or pale pigmentation. 

Variations in pigmentation may be an indicative feature to distinguish killer whale 

populations. Further non-lethal research such as photo documentation and genetic sampling 

may support the theory that distinct populations or even separate species of killer whales may 

exist in different geographical regions. 

INTRODUCTION 

• The typical diagnostic pigmentation pattern for killer whales (Orcinus orca) includes; 

~ black body 

~ white postocular patches (eye-patches) 

~ white chin 

~ white venter extending onto flanks 

~ white ventral fluke pattern 

~ grey post-dorsal saddle-patch 

• ‘White morphs’ and partially albino killer whales have been described (Fertl et al. 

1999) but these seem to be isolated occurrences. 

RESULTS 

• Variations in the basic black and white pigmentation pattern do appear to occur to 

whole populations, or groups (e.g., Berghan & Visser 2001). 

~ A group of eight killer whales sighted off New Zealand in 1997 had grey 

pigmentation and ‘dorsal capes’ – areas of darker pigment on dorsal area. 

~ A group of approximately 40 killer whales sighted off New Zealand in 2001 had grey 

pigmentation and ‘dorsal capes’. 



186

~ Some Antarctic killer whales have been described with grey pigmentation and ‘dorsal 

capes’ (Evans et al., 1982). 

• The underside of killer whale tail flukes are typically described as white (Fig. 2), 

however, some killer whales in Papua New Guinea have been noted as having grey 

under-flukes. 

• Variation in eye-patch size, shape and orientation have been described (Visser & 

Mäkeläinen 2000). 

~ Seventeen killer whales which stranded in New Zealand in 1955 had eye-patches less 

than half the size of the typical New Zealand killer whale eye-patches. 

~ Approximately 40 killer whales sighted off New Zealand in 2001 had small-sized eyepatches, 

yet the angular orientation was different from the 1955 animals. 

~ Eight killer whales sighted off New Zealand in 1997 had eye-patches at least twice the 

size of the typical New Zealand eye-patches. 

• Over 5000 photographs have been collected of New Zealand killer whales between 

1915 and 2002, yet no other images show these variations in eye-patches, a ‘dorsal 

cape’ or pale pigmentation. 

• A group of approximately 40 killer whales with light grey pigmentation patterns, 

photographed off New Zealand in 2001, had ‘lean’ profiles when compared to typical 

New Zealand killer whales. 

DISCUSSION POINTS 

• Worldwide, the typical diagnostic pigmentation pattern for killer whales is a black 

body with white areas. 

• Partially albino and ‘white morph’ animals do not necessarily represent group 

pigmentation. 

• Variations in pigmentation may be an indicative feature to distinguish groups, 

populations, sub-species or even separate species of killer whales. 

• Variations in the basic black and white pigmentation pattern include grey bodies with 

grey ‘dorsal capes’. 

• Eye-patch size and orientation appear to differ between groups and possibly 

populations of killer whales. 

SUMMARY 

• Killer whale groups, populations, sub-species or species may be separated by 

distinctive pigmentation patterns. 

• Further non-lethal research, such as photo-documentation and genetics, may support 

this theory. 

REFERENCES 

Fertl, D., Pusser, L. T., & Long, J. J. (1999). First record of an albino bottlenose 

dolphin (Tursiops truncatus) in the Gulf of Mexico, with a review of anomalously white 

cetaceans. Marine Mammal Science. 15, (1), 227-234. 

Berghan, J., & Visser, I. N. (2001). Antarctic Killer Whale Identification Catalogue. 

14th biennial conference on the biology of marine mammals, Vancouver, Canada November 

28 - December 3, 2001, 22. 



187

Evans, W. E., Yablokov, A. V., & Bowles, A. E. (1982). Geographic variation in the 

color pattern of killer whales (Orcinus orca). Report of the International Whaling 

Commission. 32, 687-694. 

Visser, I. N., & Mäkeläinen, P. (2000). Variation in eye-patch shape of killer whales 

(Orcinus orca) in New Zealand waters. Marine Mammal Science. 16, (2), 459-469. 



188

FIRST PHOTO-IDENTIFICATION MATCHES FOR PAPUA NEW GUINEA 

KILLER WHALES. 

Ingrid N. Visser 

Orca Research Trust, P.O. Box 1233, Whangarei, New Zealand. ingrid@orca.org.nz 

Photo-identification images were collected for 14 killer whales in Papua New Guinea 

waters, and a catalogue established. Matches were made for two animals – a female sighted 

two days and approximately 30 nautical miles apart, and a sub-adult male sighted 

approximately three years apart in the same region. While the IUCN does not list killer 

whales as present in Papua New Guinea waters, the records collected so far indicate it is 

found in the area for at least 10 months of the year. Thirty-three sightings from 1987 to July 

2002 were confirmed, with a further 44 sightings of unknown date or exact location recorded. 

The earliest reference to killer whales in this region was from 1956, when they were recorded 

taking fish off long-lines. Killer whales from these waters have been observed feeding on 

four species of elasmobranchs (scalloped-hammerhead shark, Sphyrna lewini; grey reef shark, 

Carcharhinus amblyrhynchos; manta ray, Manta birostris; and blue-spotted eagle ray 

Dasyatis kuhlii) and three fin-fish (yellow-fin tuna, Thunnus albacares; big-eye tuna, Thunnus 

obesus and Indo-Pacific sailfish, Istiophorus platypterus). Killer whales in Papua New 

Guinea waters have been reported in association with two species of cetaceans (sperm whales, 

Physeter macrocephalus and spinner dolphins, Stenella longirostris). 

Key words Orca, killer whale, Papua New Guinea, photo-identification, foraging, 

elasmobranchs, fin-fish. 



189

CHANGES IN CALL USE IN A RESIDENT ORCA-MATRILINE WITH A NEW- 

BORN CALF 

Brigitte Weiss & Friedrich Ladich 

Corresponding author: Weiss 

e-mail: a9400355@unet.univie.ac.at 

Institute of Zoology, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria 

Studies of the vocal behaviour of resident type orcas, Orcinus orca, in British Columbia 

(Ford1989, Ford 1991) showed that pods - social units comprised of one or more closely 

related matrilines - have unique repertoires of up to 17 discrete calls. Repertoire differences 

among pods consist of different call types and of subtypes that differ consistently in certain 

structural variables. Similar, but less pronounced differences can be found in the calling 

behaviour of matrilines belonging to the same pod (Miller & Bain 2000). None of the call 

types could be attributed exclusively to specific behaviours, and Ford (1989) argues that their 

function lies in the context of social organisation and group cohesion. Also, dialects may be 

used to discriminate between relatives and nonrelatives and might thus function as a 

mechanism for avoiding inbreeding (Treisman 1978). 

In the course of a study on the social significance of calls in resident orcas we 

investigated short-time changes in call use of a matriline before and up to three weeks after 

the birth of a calf. The birthdate is known precisely (± 1 day) and the focal matriline (the 

A30s, belonging to A-Clan of the Northern Resident Community) spent the weeks following 

the birth in the visually and acoustically well observed area of Johnstone Strait and adjacent 

waters in British Columbia, Canada. A network of radio-transmitting hydrophone stations, 

operated by the land-based research station OrcaLab, enables the underwater acoustic 

environment of the area to be monitored continuously, 24 hours a day and year-round. 

Recordings with an acceptable signal to noise ratio were available for days when the calf was 

1 - 5, 15, 19 respectively 20 days old. During all selected recordings, whales were visually 

identified and the only matriline within range of a hydrophone. Calls were classified by 

simultaneous aural and visual inspection of sonagrams, produced with Cool Edit 2000 or 

S_Tools 3.55. Classification into discrete call types, variable calls and aberrant versions of 

discrete calls mainly followed that of Ford (1989 and 1991). 

Recordings of the A30 matriline after the birth of the calf A75 in September 2001 were 

split into 5 minute samples and the entire amount of samples available per day was used for 

statistical analysis. To increase the number of samples, data for days 2 and 3, 4 and 5 and for 

days 19 and 20 after birth were pooled. As a reference, fourteen samples from nine different 

days between July 18th, 1996, and September 4th, 2001, were randomly chosen. To increase 

the number of calls taken into account 10 minutes samples were chosen. From the first day 

after birth until the family left the core area three weeks later, distinct changes in call use were 

apparent. Most apparent, call type N47 was used more than 10 times more frequently when 

the calf was one day old (Mann-Whitney: U = 11, p < 0.001, n = 30). During the following 

two weeks, the use of N47s gradually declined and recovered to values found before the birth 

(n = 77, rs = - 0.704, p < 0.001, Mann-Whitney: before vs. two weeks: U = 107.5, p = 0.448, n 

= 32). Also, within the first three weeks after the birth, call “A12 special”, a version of the N5 

call, reached values significantly higher than before the birth (Mann-Whitney: before vs. day 

19: A12 special: U = 14, p < 0.02, n = 20). Two weeks after birth the number of aberrant and 



190

variable calls was significantly higher and the number of N7s and N8s significantly lower 

than compared to pre-birth recordings (Mann-Whitney: before vs. two weeks: n = 32, N7: U = 

71.5, p < 0.05, N8: U = 69, p < 0.02, aberrant calls: U = 16.5, p < 0.001, variable calls: U = 

69, 

p < 0.05). The other calls used more or less frequently immediately after birth had 

returned to normal values. Apart from a slight increase in N4s, no more significant changes in 

call use occurred in the third week after birth (Mann-Whitney: two weeks vs. three weeks: U 

= 57.5, p = 0.017, n = 13). 

Call type N47 is almost exclusive to the A30 matriline, and “A12 special” to the closely 

related A12 matriline. Their increased use after the calf's birth may facilitate the learning 

process for the "acoustic family badge" of its own and closely related matrilines and thereby 

help to recognize and maintain cohesion with family members. 

REFERENCES: 

Ford, J. K. B. 1989: Acoustic behaviour of resident killer whales (Orcinus orca) off 

Vancouver Island, British Columbia. Can. J. Zool. 67, 727 – 745. 

Ford, J. K. B. 1991: Vocal traditions among resident killer whales (Orcinus orca) in 

coastal waters of British Columbia. Can. J. Zool. 69, 1454 – 1483. 

Miller, P. J. O. & Bain, D. E. 2000: Within-pod variation in the sound production of a 

pod of killer whales, Orcinus orca. Anim. Behav. 60, 617 – 628. 

Treisman, M. 1978: Bird song dialects, repertoire size, and kin association. Anim. 

Behav. 26, 814 – 817. 



191

SPATIAL MODELLING OF ANTARCTIC KILLER WHALE ABUNDANCE AND 

DISTRIBUTION 

Williams R., Hammond P 

Sea Mammal Research Unit, Gatty Marine Lab, University of St Andrews, St Andrews Fife KY16 

8LB, rmcw@smru.ac.uk 

The British Columbia (BC) killer whale study was initiated by Dr. Michael Bigg in 

response to an urgent need to estimate the number of killer whales in Canada’s Pacific waters 

(Ford et al. 2000). As governments attempt to manage resources on the ecosystem level, it 

will become increasingly important to estimate the abundance of top predators in the marine 

environment. 

Ford et al. (2000) calculated abundance of BC’s resident killer whales through longterm 

compilation of a photo-identification (photo-ID) catalogue, but not all populations lend 

themselves to complete enumeration. The northeast Pacific census works well, not only 

because investigators have dedicated years to their studies, but also because, as these longterm 

studies have shown, the whale populations are small, closed, accessible in inshore 

waters, and show no dispersal from the natal unit. 

This last condition is unknown in any other mammalian population, even in the BC 

transient killer whale community. Therefore, it may be appropriate to begin killer whale 

studies in other ocean basins with the expectation that a population does not follow the 

northeast Pacific resident model. In these new studies, abundance estimation may yield just 

that: an estimate, rather than a count. 

Capture-recapture analyses can be used to estimate abundance from identification 

photographs, but they become increasingly complex when a study area spans an ocean basin 

and contains an unknown number of populations (see Hammond et al. 1990). One such 

example is the Southern Ocean, where killer whale abundance has been estimated to be in the 

tens of thousands (Branch and Butterworth 2001), and where the number of ecotypes remains 

unknown. 

Line-transect surveys are the most commonly used method among a family of 

abundance estimation techniques called Distance Sampling (Buckland et al. 2001). In a 

shipboard sightings survey, ships follow a grid of systematically spaced tracklines placed 

randomly in a study area to provide representative coverage. In addition to effort, observers 

record distance and angle to each sighting of a cetacean (or group). This enables modelling 

the probability of detecting a whale as a function of perpendicular distance from the ship, to 

estimate the width of the strip effectively searched, and therefore, whale density – the number 

of animals seen per unit area searched. This mean whale density in the samples is used to 

calculate abundance, which is why design-unbiased surveys must provide representative 

coverage. 

Conventional Distance Sampling (CDS) methods allow relatively fast abundance 

estimation, but they can be very expensive. Furthermore, they calculate mean density of 



192

whales, rather than providing information on distribution. Distance sampling techniques are 

not designed to provide the additional life-history data that photo-ID studies can yield. 

Recent developments in line-transect survey design and analysis are termed Advanced 

Distance Sampling (ADS) techniques. These enable modelling effective strip width with 

environmental and biological covariates, and incorporation of geographic information for 

automated survey design (Buckland et al. 2001). A third type of ADS is Spatial Modelling, in 

which heterogeneity in whale density along transects (Hedley et al. 1999) is modelled as a 

function of environmental and spatial variables, and used to predict density throughout a 

study area. Spatial modelling allows abundance estimation for any subset of a study area 

(unlike CDS, where abundance can be estimated only for predefined strata). Similarly, they 

can identify ‘hotspots,’ areas of predicted high density. Spatial modelling techniques offer 

additional appeal in that they make no assumption about placement of tracklines. 

We believe that these two families of methods, photo-ID and spatial modelling of linetransect 

data, could play complementary roles in studying killer whale populations. Such 

studies can be conducted simultaneously, by going off-effort after a sighting is made, and 

closing in on killer whale groups to confirm school size, and to obtain identification 

photographs and biopsy samples. We use killer whales in the Southern Ocean as an example 

where preliminary work shows high killer whale abundance, while the number of populations 

present is unknown. 

We collected line-transect data from Platforms of Opportunity in the Scotia Sea during 

the austral summers of 2000-1 and 2001-2. By recording effort, as well as distance and angle 

to each sighting, we calculated killer whale density in 187 data recording sessions along 

9650km of trackline. Killer whales were sighted during 13 of these sessions, leaving 174 

tracklines along which killer whales were not seen. In total, 14 groups, totalling 61 animals, 

were spotted while on-effort. 

We used a Generalised Additive Model (GAM) to express heterogeneity of whale 

sightings as a function of spatial variables. Segments of tracklines where no killer whales 

were seen were given a 0 value for the response variable, while segments where killer whales 

were seen had a value of 1. The logit link was used to build a model describing heterogeneity 

in killer whale sightings with a logistic equation. We chose the GAM framework due to its 

flexibility in fitting the response variable (i.e., presence or absence of killer whales in a 

sampling unit) as non-linear functions of a suite of simple spatial variables (latitude, longitude 

and distance from the nearest coastline). 

Model selection was determined by Akaike’s Information Criterion (AIC), which 

selects the most parsimonious model, the one that fits the data best with the least number of 

parameters. The chosen model was used to predict killer whale density throughout the study 

area, since a value for each predictor variable could be calculated for every square in a grid 

overlaying the study area. 

The selected model predicted two areas of relatively high density, one in the Scotia Sea, 

and another in the protected waters of the Antarctic Peninsula (Fig. 1). Integrating under the 

entire density surface yielded a predicted abundance of 415 schools in the study area. This 

represents a predicted total abundance of approximately 1800 killer whales, since mean group 

size in the study was 4.3 animals. 



193

Several sources of bias may influence this estimate. The model appeared to highly 

sensitive to the few sightings made in the middle of the Scotia Sea, where relatively little 

survey effort was conducted. This calls into question the need for objective means of 

determining when a survey has provided reasonable coverage of a study area, and for means 

other than AIC for model selection. Secondly, the effective strip width component of the 

density estimate was similarly influenced by small sample size. 

However, with additional survey effort, we believe that our study will highlight the 

utility of this valuable technique, whereby line-transect survey data from Platforms of 

Opportunity are used to model patchiness of whale sightings to predict areas of high density. 

Such areas could then be targeted, increasing the efficiency of subsequent line-transect 

surveys (by a priori stratification into areas of high vs. low density) or photo-ID surveys, as 

well as other methods to investigate population structure (e.g. biopsy and acoustics). 

In practice, long-term killer whale studies have progressed by identifying and targeting 

hotspots. Spatial modelling of line-transect data from inexpensive platforms provides an 

objective means of identifying likely hotspots in new study areas, based on where animals 

were seen, and where they were not seen, in pilot studies. In a spatial modelling framework, 

line-transect data become much more informative than sightings alone, and the techniques are 

likely to have wide application in areas where killer whale studies are just beginning. 


Branch, T. A. and D. S. Butterworth (2001). “Estimates of abundance south of 60°S for cetacean species 

sighted frequently on the 1978/79 to 1997/98 IWC/IDCR-SOWER sighting surveys.” Journal of Cetacean 

Research and Management 3(3): 251-270. 

Buckland, S., D. R. Anderson, et al. (2001). Introduction to Distance Sampling: Estimating abundance of 

biological populations, Oxford University Press. 

Ford, J. K. B., G. M. Ellis, et al. (2000). Killer whales. 2nd Ed. Vancouver, UBC Press. 

Hammond, P. S., S. A. Mizroch and G.P. Donovan. (1990). Individual recognition of cetaceans: Use of 

photo-identification and other techniques to estimate population parameters. Reports of the International 

Whaling Commission (Special Issue 12). Cambridge, International Whaling Commission. 

Hedley, S. L., Buckland, S.T. and Borchers, D.L. (1999). “Spatial modelling from line transect data.” J. 

Cetacean Res. Manage. 1(3): 255-264. 



194

Figure 1. Predicted density of killer whale schools, based on a spatial model linking probability of sighting killer 

whales to smoothed functions of latitude, longitude and distance from the nearest coastline. Purple squares have 

low predicted densities of killer whale schools (except outside the study area defined by the black polygon, 

where predicted values have been coerced to zero). Abundance is calculated by integrating under the entire 

density surface. Additionally, areas of predicted high density (the red squares) could be targeted for photo-ID, 

biopsy or acoustic surveys. 



195

A BIOENERGETIC MODEL FOR ESTIMATING THE FOOD REQUIREMENTS OF 

THE KILLER WHALE (ORCINUS ORCA) 

Arliss J. Winship and Andrew W. Trites 

Department of Zoology and Marine Mammal Research Unit, Fisheries Center, University of British 

Columbia, Room 18, Hut B-3, 6248 Biological Sciences Road, Vancouver, BC, Canada, V6T 1Z4. 

Telephone – (604) 822-8183, FAX – (604) 822-8180, e-mail: winship@zoology.ubc.ca 

INTRODUCTION 

Killer whales (Orcinus orca) are top predators in their ecosystems. Quantitative 

estimates of the amount of food consumed by killer whales are critical to understanding the 

impact of this species on populations of its prey. For example, a modeling study by Barrett- 

Lennard et al. (1995) suggested that predation by killer whales may be impeding the recovery 

of some populations of the endangered Steller sea lion (Eumetopias jubatus) in Alaska. A key 

parameter in their model was the amount of food that killer whales eat each day. Estimates of 

killer whale food consumption are also important for assessing the levels of competition 

between killer whales and other marine predators (including humans). However, it is difficult 

to quantify the food consumption of cetaceans in the wild. One technique that has commonly 

been used to estimate the food consumption of cetaceans is bioenergetic modeling (Hinga 

1979; Lockyer 1981; Markussen et al. 1992). 

The first objective of our study is to develop a bioenergetic model for the killer whale 

by adapting an existing bioenergetic model (Winship et al. 2002). The model will predict the 

food requirements of killer whales, but also the uncertainty in these predictions. Our second 

objective is to use this model to estimate the number of Steller sea lions consumed by 

transient killer whales in Alaska. 

MODEL 

The model is based on the principle that, on some time scale, the energy expended by an 

organism must equal the energy consumed by the organism. Thus, by estimating all of the 

energy expenditures of an organism, one can predict the amount of energy required to meet 

those energetic demands. Information about the organism’s diet can then be used to convert 

predicted caloric requirements to estimates of prey intake. The model’s outputs are 

predictions of the amounts of prey consumed by killer whales of each age and sex. 

The parameters in the model can be grouped into two categories: bioenergetic and diet. 

Bioenergetic parameters include body size, body composition, activity budgets, resting and 

active metabolic rates, and digestive efficiency. Diet parameters include diet composition (the 

proportion of diet biomass comprised of each prey species), energy density of prey, and the 

parts of prey that are consumed. Data are available for some parameters (e.g., body size— 

Clark et al. 2000; metabolic rates—Kriete 1995; and activity budgets—Saulitis et al. 2000), 

however there are very few data currently available for other parameters. To incorporate this 

uncertainty in parameter values the model has a Monte Carlo random sampling routine that 

calculates (explicitly and quantitatively) the uncertainty in the model’s predictions (Fig. 1). 

This allows us to examine the relative impact of uncertainty in different parameters on the 

precision of the model’s predictions. 



196

Probability 

Randomly choose parameter 

values from specified 

sampling distributions 

Parameter value 

Frequency 

1,000,000 times 

Food requirements 

Run model to obtain 

point estimate of 

food requirements 

Figure 1. Monte Carlo random sampling technique used to estimate error in model predictions. The model 

output is a distribution of point estimates of food requirements (rather than a single point estimate) from which 

we can calculate the error in the model’s predictions. 

OUTCOME 

The predictions from our model will provide estimates of the food requirements of killer 

whales and the uncertainty in these estimates. These estimates can then be incorporated into 

predator-prey or multi-species models to examine the role of killer whales in their 

ecosystems. Our specific application of the model will provide an estimate of the number of 

Steller sea lions that are consumed by transient killer whales in Alaska. 

Importantly, the results of our modeling study will indicate key areas of killer whale 

biology that need more research to further refine estimates of killer whale prey consumption. 


Barrett-Lennard, L. G., K. Heise, E. Saulitis, G. Ellis, and C. Matkin. 1995. The impact of 

killer whale predation on Steller sea lion populations in British Columbia and Alaska. 

North Pacific Universities Marine Mammal Research Consortium, Fisheries Center, 

University of British Columbia. 

Clark, S. T., D. K. Odell, and C. T. Lacinak. 2000. Aspects of growth in captive killer whales 

(Orcinus orca). Marine Mammal Science 16:110-123. 

Hinga, K. R. 1979. The food requirements of whales in the southern hemisphere. Deep-Sea 

Research A26:569-577. 

Kriete, B. 1995. Bioenergetics in the killer whale, Orcinus orca. Ph.D. thesis, University of 

British Columbia, Vancouver, 138 pp. 

Lockyer, C. 1981. Growth and energy budgets of large baleen whales from the southern 

hemisphere. Pp. 379-487 in Mammals in the seas: general papers and large cetaceans. 

FAO Fisheries Series 5, Rome, 4:1-504. 

Markussen, N. H., M. Ryg, and C. Lydersen. 1992. Food consumption of the NE Atlantic 

minke whale (Balaenoptera acutorostrata) population estimated with a simulation 

model. ICES Journal of Marine Science 49:317-323. 



197

Saulitis, E., C. Matkin, L. Barrett-Lennard, K. Heise, and G. Ellis. 2000. Foraging strategies 

of sympatric killer whale (Orcinus orca) populations in Prince William Sound, 

Alaska. Marine Mammal Science 16:94-109. 

Winship, A. J., A. W. Trites, and D. A. S. Rosen. 2002. A bioenergetic model for estimating 

the food requirements of Steller sea lions Eumetopias jubatus in Alaska, USA. Marine 

Ecology Progress Series 229:291-312. 



198

WHY DO SOME KILLER WHALES TALK SO MUCH? 

Harald Yurk 1, John K.B. Ford 2, Craig O. Matkin 3, Eva S. Saulitis 3,Lance G. Barrett-Lennard 4, & 

Kathy Heise 1 

1 University of British Columbia, 

2 Fisheries and Oceans Canada 

3 North Gulf Oceanic Society, 

4 Vancouver Aquarium Marine Science Centre 

Killer whales show great variety in repertoire size and vocal rates of their discrete 

vocalizations. In contrast to many smaller delphinids, killer whales do not show linearly 

increasing vocal rates with bigger group sizes. There are a number of possible reasons why 

vocal rates differ among killer whale groups, sub-populations and populations. Vocal rates 

might be adapted to the foraging on a particular prey type, (e.g. fish with limited hearing 

abilities versus mammal with well developed broad range hearing abilities), or vocal rates 

reflect long term associations among individuals, in which case a constant exchange of 

vocalizations to synchronize behaviour is only necessary when different groups mix. If 

learning and maintaining a particular repertoire of calls were costly than repertoire size would 

usually depend on the effects it has on breeding success. This appears to be true for some 

songbirds, where bigger song repertoires of male birds equal greater mating success although 

repertoire size might not be the selected trait but a side effect of selection on repertoire 

sharing (Beecher 2000). 

In the Northeastern Pacific, two populations of killer whales, transients and residents are 

strikingly different in their vocal behaviour. Transients appear to vocalize infrequently 

(Ford1984) and have small vocal repertoires of discrete calls. Call rate and repertoire size of 

transients could be seen as an adaptation to their foraging method on marine mammals (Ford 

1984; Deecke, pers. comm., see also chapter in this volume). Residents, which prey on fish, 

vocalize more frequently and also have greater repertoires of discrete calls than transients 

(Ford 1984). Residents are also characterized by long-term associations of matrilinealy related 

individuals. 

In the following pages we will take a closer look at the vocal behaviour of residents 

with regard to the following issues: 1. Call repertoire size, 2. Call structure diversity, and 3. 

Call rates and repertoire use. Because this manuscript is based on work-in-progress, the 

trends reported here should be considered as tentative. 

CALL REPERTOIRE SIZE 

The number of discrete call types that each pod or group of closely related matrilines 

uses ranges from 7-17. All members of the matriline use the same set of learned calls (Ford 

1991; Ford 1991; Miller and Bain 2000; Yurk, Barrett-Lennard et al. 2002) and the repertoire 

size appears to be more closely correlated with the number of matrilines within a pod than to 

the number of individual whales within that same group. 

Ford (1991) and Deecke, Ford et al. (2000) proposed that cultural drift by which 

accumulated copying errors change the structure of call types is the main mechanism to 

explain repertoire divergence. However, this process does not explain rapid changes in 

repertoire size after group-fission (Yurk, Barrett-Lennard et al. 2002), and the lack of gradual 



199

change in call structure for call types that are more complex (Deecke, Ford et al. 2000; Yurk, 

Barrett-Lennard et al. 2002). (Yurk, Barrett-Lennard et al. 2002) proposed instead that 

repertoire differences could be achieved by selectively dropping calls and changing the 

frequency of others during matriline fission, while similarity is maintained by keeping the 

majority of calls stable, and only allowing certain call structures to change gradually over 

time. This process requires that the call structure of discrete calls is hierarchical (Ford 1984; 

Yurk, Barrett-Lennard et al. 2002), and that the process of call development is based on the 

transmission of structural parts rather than whole calls. 

CALL STRUCTURE DIVERSITY 

Fig. 1: Spectrographic example of a discrete call. Calls often consist of two components, a) a lower frequency component – 

LFC (duration : 0.5 to 2 sec/ pulse repetition rate: 0.2 to 2.5 kHz), and b) an upper frequency component – UFC (duration: 

0.5 –2.5 sec/ frequency range: 4 to 8 kHz) . Abrupt shifts of the pulse frequency in the lower frequency component 

distinguish elements. Elements differ from call segments that are characterized by silent intervals between them. 

The structure of call types is divided hierarchically into parts (Fig.1) (Ford 1984). Yurk, 

Barrett-Lennard et al. (2002) named different parts according to frequency contour shifts and 

temporal discontinuities as components, segments, and elements. The call organization 

appears to be preserved in the process of call transmission between generations. Groups of 

matrilineal related residents in Alaska show structural integrity although each part differs 

between groups (Fig. 2). 



200

Figure2: Spectrographic examples of a shared call type of four resident pods in Southern Alaska. The structural similarity 

decreases from left to right mainly within one element, while all segments and elements are present in all four calls. 

Repertoire similarity also decreases from left to right between the four pods. 

The structural variation of the same call type is more prominent within segments and 

elements of the lower frequency component of the calls, while the upper frequency 

components appear to be less affected by transmission related changes. This reduced variation 

of the upper frequency components could imply a selected functional purpose of those 

components, e.g. to coordinate group movements because of a greater directionality of this 

component as proposed by Miller (2002). 

When frequency contours of calls are compared between different clans that do not 

share complete call types, some elements and segments still appear to be similar. Even 

between sub-populations those similarities persist although they are more obvious in call 

segments than in call elements. Therefore, it might be better to define call types on the basis 

of the frequency contours of their structural parts rather than complete contours, and compare 

elements and segments between clans and sub-populations to determine acoustic 

relationships. 

CALL RATES AND REPERTOIRE USAGE 

Call repertoires, or dialects (Ford 2002), are cultural indicators of relatedness (Yurk, 

Barrett-Lennard et al. 2002), and could function as an inbreeding avoidance mechanism if 

used in mate choice (Ford 1991; Barrett-Lennard 2000). Because repertoire size varies among 

groups and is correlated with the number of matrilines in a dialect group or clan, repertoire 

acquisition and maintenance could be a true signal of rank and success of a clan. Repertoire 



201

use and call rate should reflect such a ranking system during vocal exchanges between 

members of different clans and/or by mediating access to rich food sources. 

There is some evidence for such an acoustically mediated ranking system among 

Alaskan residents. During the summer months residents usually prey on returning salmon in 

inlets or passages that create funnels for returning fish. Members of the repertoire rich ABclan 

prefer foraging in a passage that usually contains higher prey densities than most of the 

surrounding areas. Members of this clan appear to consistently use a greater proportion of 

their repertoire even when by themselves (Fig. 3a), but especially when in contact with 

members of the AD-clan (Fig. 3b), the other clan within the Southern Alaskan resident 

community. However, some members of the AD-clan, the AE matrilines frequent an adjacent 

area to the one mentioned above, and are highly vocal in the presence of AB-clan whales. 

Members of the AB matrilines appear to use fewer call types than when alone and call less 

frequently when in direct contact with AE matrilines (Fig.3c). 

A) 

30.000 

25.000 

20.000 

15.000 

10.000 

5.000 

0.000 

l 

AB 

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 

18.000 

16.000 

14.000 

12.000 

10.000 

8.000 

6.000 

4.000 

2.000 

0.000 

AB 

B) 

30.000 

25.000 

20.000 

15.000 

10.000 

5.000 

0.000 

AB w. AD 

0 0.2 0.4 0.6 0.8 1 

AB with AD matrilines 

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 

C) 

Figure 3: Calling behaviour of AB matrilines during encounters with matrilines from another clan or when alone. 

Proportional repertoire usage on x-Axis versus call rate on y-Axis. A) AB matrilines alone (14 encounters), B) AB matrilines 

in contact with AD clan whales (7 encounters), C) Changes of repertoire use and call rate during encounters of AB matrilines 

with members of AD clan (7 encounters). 

Repertoire size, use and call rate might be a cultural means by which resident killer 

whales mediate access to food sources. Access to food sources will ultimately affect the 

survival of clans. 


Barrett-Lennard, L. G. (2000). Population structure and mating patterns of killer 

whales, Orcinus orca, as revealed by DNA analysis. Zoology. Vancouver, BC, 

Canada, University of British Columbia. 

Beecher, M. D. (2000). "Territory tenure in song sparrows is related to song sharing with 

neighbours, but not to repertoire size." Animal Behaviour 59(1): 29-37. 

AE 



202

Deecke, V. B., J. K. B. Ford, et al. (2000). "Dialect change in resident killer whales: 

implications for vocal learning and cultural transmission." Animal Behaviour 60(5): 

629-638. 

Ford, J. K. B. (1984). Call traditions and dialects of killer whales (Orcinus orca) in British 

Columbia. Zoology. Vancouver, University of British Columbia. 

Ford, J. K. B. (1991). "Vocal traditions among resident killer whales (Orcinus orca) in coastal 

waters of British Columbia." Canadian Journal of Zoology 69: 1454-1483. 

Ford, J. K. B. (2002). Dialects. The Encyclopedia of Marine Mammals. W. F. Perrin, B. 

Wursig and H. G. M. Thewissen. New York, Academic Press. 

Miller, P. J. O. (2002). "Mixed-directionality of killer whale stereotyped calls: a direction of 

movement cue?" Behavioral Ecology and Sociobiology 52(3): 262-270. 

Miller, P. J. O. and D. E. Bain (2000). "Within-pod variation in the sound production of a 

pod of killer whales, Orcinus orca." Animal Behaviour 60(5): 617-628. 

Yurk, H., L. G. Barrett-Lennard, et al. (2002). "Cultural transmission within maternal 

lineages: vocal clans in resident killer whales in southern Alaska." Animal Behaviour 

63(6): 1103-1119. 



203

Index of Authors 

Azevedo, 47 

Bain, 146, 168 

Baird, 86 

Balcomb, 181 

Barbraud, 124 

Barrett Lennard, 98 

Barrett-Lennard, 27, 33, 58, 83, 89, 129, 

202, 206 

Bassoi, 51 

Batty, 66 

Bell, 112 

Bester, 36 

Black, 41, 86, 159 

Bradley, 92 

Burdin, 67, 95, 109 

Chambellant, 112 

Cloutier, 77 

Dahlheim, 41, 46, 86 

Dalla Rosa, 47, 51 

Damsgård, 55 

Danilewicz, 51 

de Stephanis, 141 

Dedeluk, 58 

Deecke, 60 

DeLeuw, 46 

Delfour, 65 

DeMaster, 83 

Desrosiers, 77 

Domenici, 66 

Ellifrit, 46 

Ellis, 31, 41, 70, 74, 98, 105, 120, 129, 

132, 134, 149 

Filatova, 67, 109 

Flores, 51 

Flores de Sahagún, 78 

Foote, 71 

Ford, 58, 60, 74, 89, 129, 163, 168, 202 

Gasparrou, 87, 88 

Gendron, 78 

Gill, 112 

Gillham, 70 

Godefroid, 77 

Guerrero-Ruiz, 78 

Guinet, 124, 141 

Hammond, 79, 195 

Hanson, 92, 137 

Harvey, 70 

Heise, 83, 98, 202 

Hoelzel, 46, 86 

Holst, 92, 137 

Hoyt, 67, 109 

Iñíguez, 87, 88 

Irish, 89 

Jikiya, 109, 154 

Jones, 71 

Keith, 36 

Kriete, 91 

Ladich, 193 

Lailson-Brito, 47 

Leyssen, 55, 92 

Maldini, 95 

Mangin, 124 

Maniscalco, 95 

Martell, 83 

Matkin C., 98, 120, 134, 202 

Matkin D., 101 

Matkin, C., 83 

Michaud, 77 

Miller, 108, 136, 139 

Mironova, 67, 109 

Moreno, 51 

Morrice, 112 

Natoli, 86 

Nicholson, 86 

Nikulin, 109 

Øien, 92, 137 

Olavarria, 86 

Olesiuk, 98, 120 

Osbourne, 71 

Pakenham, 123 

Paton, 112 

Pavlov, 109 

Pérez Gimeno, 141 

Peter, 120 

Pistorius, 36 

Plater, 155 

Poncelet, 124, 141 

Rehn, 163 

Riesch, 163 

Ross, 129 

Salazar Sierra, 141 

Santos, 51 

Sato, 67, 109 

Saulitis, 83, 98, 120, 134, 202 

Sautilis, 101 

Schulman-Janiger, 41 



204

Secchi, 47 

Shapiro, 136 

Sigurjonsson, 185 

Similä, 55, 66, 92, 137, 175, 185 

Simon, 139, 140 

Slater, 60 

Smith, 146 

Solow, 136 

Stap, 41 

Straley, 149 

Tarasyan, 67, 109, 154 

Taylor, 70, 155 

Teichert, 163 

Ternullo, 41, 159 

Thiele, 112 

Thomsen, 163 

Tossenberger, 87, 88 

Trites, 83, 89, 168, 199 

Tyack, 136 

Ugarte, 139, 140, 171, 177 

Urbán-R, 78 

van den Hoff, 112 

van Ginneken, 181 

Veirs, 71 

Vikingsson, 185 

Visser, 186, 189, 192 

Wahlberg, 139 

Weiss, 193 

Williams, 71, 168, 195 

Winship, 199 

Yurk, 98, 202 



208

REMERCIEMENTS 

Le quatrième symposium international et groupes de travail sur les orques 

s’est déroulé au Centre d’Études Biologiques de Chizé du lundi 23 septembre au 

samedi 28. Le quatrième symposium s’intégrait dans le cadre du programme des 

colloques intitulés "Les entretiens de Chizé". 

Ces rencontres ont donné l’opportunité à 70 chercheurs et étudiants de se 

rencontrer, d’échanger des informations et de mettre en place des collaborations. 

Nous avons rassemblé les personnes qui travaillent sur toutes les études en cours 

dans le monde. Il y a eu 21 pays représentés et plusieurs études dans de nouveaux 

sites ont été présentées lors du colloque : notamment au Kamtchatka, Brésil, 

Nouvelle Guinée ou le détroit de Gibraltar. Plusieurs problèmes de conservation ont 

été abordés lors de ce colloque, interaction avec les pêcheries, pollution… 

Ce symposium et les groupes de travail qui ont suivi n’ont pu être organisés 

que grâce au soutient de l’ensemble du personnel du CEBC-CNRS qui se sont 

considérablement investis pour accueillir, héberger et restaurer les participants. Nous 

souhaitons aussi remercier vivement Karine Delord pour le travail remarquable 

effectué pour l’organisation et la gestion de ce colloque, Renaud de Stephanis pour 

l’important travail de mise en page de ces proceedings. 

Ces réunions n’auraient pas pu avoir lieu sans le soutient important apporté 

par le programme Com’Science du Conseil Régional du Poitou-Charentes, du 

Conseil Général des Deux-Sèvres et du Marineland d’Antibes. 

Enfin, nous remercions l’ensemble des participants pour la qualité de leur 

contribution. C’était un plaisir de partager ces moments avec vous. 

Merci à vous tous 

Le comité organisateur. 



209

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