bycatch of humpback whales in artisanal fishing gear in ecuador ...

IWC Workshop on Comprehensive Assessment of Southern
Hemisphere Humpback Whales, Hobart, Tasmania: 3-7 April 2006
BYCATCH OF HUMPBACK WHALES IN ARTISANAL FISHING GEAR IN
ECUADOR DURING 2005
FERNANDO FÉLIX 1,2 , MERCEDES MUÑOZ 1 AND BEN HAASE 1
1 Fundación Ecuatoriana para el Estudio de Mamíferos Marinos. P.O. Box 09-01-11905, Guayaquil, Ecuador.
2 Pontificia Universidad Católica del Ecuador. Av. 12 de Octubre y Patria, Quito, Ecuador.
Contact e-mail: fernandofelix@femm.org.
ABSTRACT
Southeastern Pacific humpback whales (Group G) breed along the coasts of Ecuador, Colombia and
Panama during the austral winter (July-October). Bycatch and stranding information collected during
more than a decade in Ecuador indicate that the entanglement in fishing gear is a major threat for
humpback whales during the breeding season. Here we report three new cases of individual whales
entangled in artisanal gillnets recorded from whalewatching vessels off Salinas (02º10’S, 81ºW) in
2005. From the obtained photographs the fishing gear was identified as multifilament gillnets used by
artisanal fishermen for large pelagic fish. The bycatch rate was estimated to be 0.0086 based on the
total number of whales recorded in 74 trips (n=349). Extrapolating this value to the entire population,
the total bycatch in Ecuador in 2005 was estimated to be 25 whales (C.I. 95% 20-32). This high
bycatch rate is the result of the overdimensioned artisanal fishing fleet and the lack of fishing
management. Although several published reports have informed about the subject, the problem
remains unattended by local authorities.
KEY WORDS: BYCATCH, GILLNETS, HUMPBACK WHALE, BREEDING GROUNDS, SOUTH
AMERICA
INTRODUCTION
SC/A06/HW14
Cetacean bycatch in fishing gear is a conservation issue of increasing concern due the potential
impact on natural populations (Northidge, 1985; IWC, 1994; Reeves et al., 2003; Read et al., 2004).
Interactions with fisheries occur mainly with artisanal and industrial fishing gillnets and both small and
large cetacean species are involved. The global bycatch is estimated to be in hundreds thousands
cetaceans, although in most regions the information is still fragmentary (Read et al., 2005). Due to its
coastal distribution, the humpback whale (Megaptera novaeangliae) is one of the most threatened
species. A few attempts to assess the bycatch impact on humpback whales have been made at
feeding ground (e.g. Lien, 1994; Jooke and Matilla, 2001; Baird, 2003; Johnson et al., 2005) but much
less is known from breeding grounds in tropical areas where the problem would have different
characteristics.
Bycatch has been identified as the major anthropogenic threat for the Southeastern Pacific humpback
whale stock (Group G; see IWC, 1998) during the breeding season in Ecuadorian and Colombian
waters (Félix et al., 1997; Félix and Haase, 2005; Álava et al., 2005; Capella et al, 2001: Florez-
González et al., in press). Most cases of bycatch in Ecuador occurred in artisanal multifilament gillnets
of 4-5in wide mesh and to a lesser extent in industrial gear (Félix et al., 1997). Álava et al. (2005)
estimated that around a third (29%) of the humpback whales stranded on the coast of Ecuador during
the period 1991-2004 had gillnets around their bodies or deep cuts in the appendages and tailstock.
All these reports have highlighted the potential impact of fisheries on the population, although no
attempts have been made to quantify its magnitude.
A priority activity of conservation in the UICN Action Plan for cetaceans 2000-2010 (Reeves et al.,
2003) and in the CMS Workshop on Aquatic Mammals in South America (Hucke-Gaete et al., 2004)
was assessing the impact of fisheries in Eastern tropical Pacific countries. The case of Ecuador is of
particular concern because the country has the largest artisanal fishing fleet of all the Southeast
Pacific countries (CPPS, 2003). By the end of the 90s, the artisanal fleet in Ecuador was formed by
around 15,500 boats and 56,000 fishermen; this is around 5% of the Active Economic Population
inhabiting the Ecuadorian coast (Solís-Coello and Mendívez, 1999; Martínez and Viteri, 2005). Around

50% of the fleet uses multifilament gillnets of 4-5” wide mesh up to 3km in length as main gear to
catch large pelagic fish (sharks and billfish) (Martínez et al. 1991).
Here we present new cases of humpback whales entangled in artisanal gillnets found off Salinas,
Ecuador (2º10’S, 81º’W) (Figure 1). In contrast to previously reported beachings, these new cases
involved live whales. The new approach allowed estimating the magnitude of the total bycatch at
taking into account the survey effort of the season.
METHODS
Figure 1. The study area located at Salinas, Ecuador.
Whalewatching boats have been used as research platform during a long-term study of the
humpback whale in Ecuador (see Félix and Haase, 2001a for details). Data analyzed in this report
was obtained during the breeding season 2005 (late June-early October). Seven different boats were
used with size ranging between 7 and 15 m in length and 10-30 passengers of capacity. Usually
boats departed at 9:00 in the morning and lasting two or three hours. Occasionally trips were also
made in the afternoon. During the trips, information on survey effort, oceanographic conditions, whale
behaviour, heading, group size and composition was filled out on data forms. As a standard
methodology, whales were photographed with a Canon Rebel Digital camera (6.3 megapixels)
equipped with a 70-300mm zoom lens for individual identification.
RESULTS
Effort
Seventy four trips were made between 27 th June and 1 st October 2005. A total of 349 whales in 148
groups were recorded. Total navigation time was 156 hours, of which 59 hours were spent with the
whales. The surveyed distance was 2,031km. Table 1 shows the monthly effort deployed through the
season. July and August were the months with the largest effort with trips almost everyday and then
the effort decreased considerably in September when tourist activities also decreased.
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Table 1. Research effort by month. Period (June-October 2005).
June July August September October Total
Number of trips 4 33 33 3 1 74
Number of groups sighted 5 75 64 4 - 148
Number of whales 10 174 155 10 - 349
Observation time (min) 268 1,729 1,434 112 - 3,543
Net navigation time (min) 277 2,348 2,723 342 - 5,690
Total navigation time (min) 545 4,077 4,157 454 143 9,376
Distance surveyed (km) 120 924 866 89 31 2,031
The Cases
Three entangled whales were recorded during the trips in the season 2005: June 26, August 10 and
August 11. All three cases involved adult animals. Photographs of the dorsal fin indicated that whales
were different individuals. Since only the back of the whales was visible during the encounters, it was
not possible to determine the seriousness in each case and if the whale had the chance to get rid of
the net (Figure 2). The whale found in June had the net around the anterior part of the body including
the head, but apparently the tail was free; however, a long strip of net with yellow floaters showed the
whale was towing several meters of gear. The individual found in August 10 was a female with a
newborn calf seen for short time; in this case, apparently only the adult animal was seen with a net a
long the side of the body. The case of August 11 did not directly look fatal, since just the part of a net
was around the central part of the back and the dorsal fin, although also flippers and the tail could be
entangled.
The whale found in June moved slowly and stayed around the same area but it was evident along the
observation period that the net impacted and slowed down its movements. In contrast, the other two
cases whales apparently moved without problems. In the first and second cases whales moved a few
hundred meters from shore off the Salinas tip, but the third whale was recorded 2-3 km north of this
point.
Figure 2. Whales found entangled during the season 2005 off Salinas: June 26 (top); August 10
(middle); and August 11 (bottom).
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Bycatch rate and total mortality
Considering the total number of whales recorded (n=349) and the three whales found entangled, a
bycatch rate of 0.0086 was calculated. Extrapolating this value to the entire population estimated to
be 2,917 animals in the period 2003-2004 (Félix et al., 2006), around 25 whales (C.I. 95% 20-32)
could be the total bycatch in the breeding season 2005 in Ecuador.
DISCUSSION
The entanglement of humpback in artisanal gillnets in Ecuador continued in 2005 likely with similar
intensity as previous years. Besides the three cases reported here, the authors knew of two other
cases which occurred in other parts of the country involving beached whales with gillnets around their
bodies. Also, sailors and naturalist guides reported entangled whales off Salinas every year since
whalewatching started here in 2001; at least three cases were reported in 2003 (Félix and Haase,
2003). Other cases of entanglements were reported at La Plata Island, 100km north of Salinas, a calf
in 1998 (Scheidat et al., 2000) and six adults or sub-adults animals in 2001 (Álava et al., 2005).
It is believed that the entanglement of humpback whales in artisanal gillnets in Ecuador and Colombia
have maintained an increasing trend in the last decade (Capella et al., 2001; Álava et al., 2005), but
there not proof as no reliable assessments have been made. So far, data on beached animals have
provided a gross idea of the bycatch level but not its magnitude, since not every entangled or dead
whale ended up on the beach. Our estimate provides a first approach to establish the total bycatch in
Ecuador by using a measurable searching effort and therefore allowing extrapolation for the entire
population that reach Ecuador. However, it is not possible to establish the impact on the population
since no data on survival after the entanglement are available. Photographs of the animals found off
Salinas in 2005 showed different level of seriousness with likely different survival chances for the
whales; therefore, it is not possible to obtain an overall rate.
The fate of the entangled whales was unknown, but previous records of stranded animals on the
coast of Ecuador suggest that at least some whales die few weeks later after the entanglement (e.g.
Félix et al, 1997; Álava et al, 2005). These animals would die of exhaustion or would be easy preyed
upon by orcas and big sharks at sea. In the female with calf case (#2), the impact would be even
bigger, since calves also would die afterwards. Whatever the proportion of animals dying as a
consequence of the entanglement, it may have a significant impact in the recovery of this population.
Since both fishing effort and whale population are increasing in Ecuador (see Félix et al, 2006), it is
expected that the number of entangled whales will continue increasing in the future if measurements
are not taken on short-terms. Several management actions have been proposed by Ecuadorian
researches in order to reduce the level of cetacean bycatch, including directed research; education
programs for artisanal fishermen; use of sound devices; closed seasons; change of fishing gear;
creation of rescue teams; among others (Félix and Samaniego, 2004; Félix et al, 1997; Álava et al,
2005; Félix and Haase, 2005). Some of these measures could be implemented on a temporary basis
during the humpback whale breeding season or in specific sites of higher density of whales. With
exception of a limited number of educative talks during the seasons 2002 and 2003 no other actions
have been taken by fishing authorities.
Considering that such high bycatch rate of a long-migrating species as the humpback whale has
transboundary implicitness, we ask to the Scientific Committee of the International Whaling
Commission to urge Ecuadorian authorities the adoption of measures to reduce the level of bycatch
on short-term. We also recommend that any proposal and or decision to be taken to address the
bycatch problem must be agreed with relevant stakeholders including fishing authorities, artisanal
fishermen associations, NGOs, among others.
ACKNOWLEDGEMENTS
We thank tourist operators in Salinas who allowed us using their vessels for this study. The humpback
whale research in Ecuador is supported by the Whale and Dolphin Conservation Society (WDCS).
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