13.07.2015 Views

Seaquest Basking Shark Project (SBSP) 2009 - Cornwall Wildlife Trust

Seaquest Basking Shark Project (SBSP) 2009 - Cornwall Wildlife Trust

Seaquest Basking Shark Project (SBSP) 2009 - Cornwall Wildlife Trust

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

1. Aims and objectivesThe basking shark is the world’s second largest fish. It is distributed throughout theworld’s oceans and is a frequent visitor to the seas around the Cornish coast. It iseasy to observe and has been hunted for its oil and fins. However many aspects ofthe basking shark’s natural history remains unknown. For this reason research intothe lives of these protected and vulnerable creatures is important if it is to survive asa species.The aims of the <strong>Seaquest</strong> <strong>Basking</strong> <strong>Shark</strong> <strong>Project</strong> (<strong>SBSP</strong>) were to improve protectionfor basking sharks around <strong>Cornwall</strong> and the Isles of Scilly by:• Providing a deeper understanding of basking shark distribution and behaviour.• Encouraging the reporting of live and dead basking sharks.• Collecting information on the threats to basking sharks.• Providing the findings to decision makers to inform conservation actionincluding the development of Marine Conservation Zones.• To involve new volunteers by participating in the project.• To educate the public about basking sharks in particular and conservation ingeneral.• To work with other organisation and groups to gather data and to protectthe marine environment.3


2. Species information<strong>Basking</strong> shark (Cetorhinus maximus)Taxonomy:Phylum ChordataClass ChondrichthyesSubclass ElasmobranchiiOrder LamniformesFamily CetorhinidaeTaxon Cetorhinus maximus (Gunnerus)Common name basking sharkPhoto 2: <strong>Basking</strong> shark. Photo by Colin Speedie (2000)4


Plate1: Distinctive features of the <strong>Basking</strong> shark5


2.1 Distinctive features of the basking shark (see plate 1)• Large size. Elongated and stout body, up to 11m long (though largerindividuals have been recorded). 4 tonnes in weight.• Gill slits which virtually encircle the head used to exchange oxygen.• Gill rakers that enable the shark to retain its prey, often visible whenviewed feeding at close range. The exact mechanism whereby therakers work is not fully understood. Sims et al (2005).• Prominent pointed snout.• Small eyes.• Large, round mouth with hundreds of minute and vestigial teeth.• Notched tail and large, angular dorsal and pectoral fins.• Mottled grey/brown colouration.(Bloomfield and Solandt, 2007)<strong>Basking</strong> sharks are members of a group of successful aquatic species that are believedto have evolved during the lower Carboniferous Period (Compagno et al, 2005).They are the second largest fish in the world and the largest in the NortheastAltlantic, growing up to 11m in length and are one of the three species of filterfeeding shark. The others are the megamouth (Megachasma pelagios) and the whaleshark (Rhincodon typus).<strong>Basking</strong> sharks have a grey/brown colouring and are seen swimming slowly, and“basking”, on the surface, particularly in summer months around the western coastsof the British Isles. On the west coast of Ireland they are known as sun fish. Theirdorsal fin, tail fin and nose are visible as they feed on surface aggregations ofplankton as illustrated by the photographs reproduced in this report. This highlyvisible behaviour means that they are a species particularly suited to effort basedobservation.6


appears to have few predators, apart from man. As such it can be seen as a highlyadapted, successful species.According to Sims et al (1997) and Sims and Quayle (1998) basking sharksconcentrate their feeding along thermal fronts and tidal fronts where plankton canbe found at high concentration levels. These “frontal systems” are where waterbodies of different temperature, salinity, nutrition and density meet creating areas ofintense phytoplankton growth. Zooplankton biomass increases in response to thephytoplankton, in turn attracting the sharks.However, Sims et al (2005) have revised their assumptions regarding C. maximus’feeding habits on the basis of new research information which showed the speciesemploying a wide range of feeding strategies within the water column andgeographically. They consequently raised the question of the validity of drawing toomany conclusions from observation of surface behaviour. However effort basedshore based observations are a cost effective way of obtaining valuable long termcomparative data of shark numbers, surface behaviour and interactions withassociated species. <strong>Basking</strong> sharks are often seen in aggregations of other species offish, cetaceans and seabirds, that are feeding together, but at different levels in thefood chain.2.3 ReproductionDoyle et al (2005) say that “The life history of basking sharks is little understood”. This isunderlined in their summary of research that suggests C. Maximus may live up to 50years, reach sexual maturity in 12-15 years (males), 18 years (females) and produceyoung at 2-4 year intervals following gestation periods of 12-36 months. To datethere have been no verified observations of birthing. Courtship behaviour,characterised by nose to tail and parallel swimming has been frequently observed onthe surface, though mating behaviour is rarely seen.<strong>Basking</strong> sharks have been observed breaching where they leap out of the water andcrash back, somewhat inelegantly. The amount of energy required to do this from aspecies not known for its vigour is estimated as being considerable (Galpin. J. <strong>2009</strong>).8


The reason for breaching is not known but may be associated with courtship orparasites removal. <strong>Shark</strong>s have been seen breaching two or three times insuccession.2.4 DistributionC. maximus is described as being “primarily coastal-pelagic, occurring in thetemperate, and insular shelves of the Atlantic and Indo- Pacific Oceans and theMediterranean Sea” (Marine Conservation Society - Simms, 2003). However,research by Gore et al (2008) suggested that these sharks may not be confined todiscrete populations but move across oceans and swim at greater depths thanpreviously thought, having tracked one female from the Isle of Man toNewfoundland. Skomal (2008) reported basking sharks tagged off the easternseaboard of the United States being tracked as far south as the coast of Brazil.Sims, based at Marine Biological Association, has written, with others, extensivelyabout their findings and has used tracking technology to advance knowledge aboutthe habits and range of C. maximus. Sims et al (2005) also refers to the understandingof the genetic diversity of C. maximus and whether it is a single world-wide species.They concluded in The <strong>Basking</strong> <strong>Shark</strong> Assessment that the evidence supports theproposition that C. maximus is a single species. The research by Gore and Skomal(2008) could be seen as supporting this view.The Food and Agriculture Organisation (FAO) describe the world wide distributionof basking sharks as follows:• Western Atlantic: Newfoundland to Florida; southern Brazil to Argentina.• Eastern Atlantic: Iceland, Norway and western Barents Sea to Mediterraneanand Senegal; (This includes UK waters).• Western Cape Province, South Africa. Western Indian Ocean.• Eastern Cape Province, South Africa.• Western Pacific: Japan, the Koreas, China, Australia (New South Wales,Victoria, Tasmania, South and Western Australia), New Zealand.9


• Eastern Pacific: Gulf of Alaska to Gulf of California, Ecuador, Peru and Chileand Galapagos Islands.2.5 Risk and ExploitationThe Marine Conservation Society (2004) suggested that basking sharks have thecharacteristics (large size, slow to reach sexual maturity, uncertainty about breedingrates, ease of capture and damage by boats and fishing gear) of a species that is“extremely vulnerable” to over exploitation. According to Sims et al (2005) “Thisinherent vulnerability to exploitation, together with concern over the strong possibility thatpopulations are depleted as a result of exploitation by fisheries and the lack of scientificknowledge of the species, has led to the basking shark being listed as Vulnerable worldwideand Endangered in the north-east Atlantic, (2004).” C. maximus has the features, knownas gigantism, associated with many very large creatures, such as many cetaceans, thatmakes them vulnerable to becoming extinct.Prior to 1999 C. maximus was hunted throughout its habitat ranges in the Northernand Southern Hemispheres, primarily for the high grade oil from its liver but also forthe shark fin trade. Fisheries existed in temperate waters around the world,primarily in Scotland, Ireland, Norway, Iceland, California, China, Peru and Ecuador.The fishery at Achill Island, Ireland, took over 12, 000 basking sharks between 1947and 1975 (<strong>Shark</strong> <strong>Trust</strong>, <strong>2009</strong>). During the period 1946 to 1986 the European fisherytook 77,204 basking sharks. The Norwegians landed the majority of basking sharks inthe NE Atlantic, taking 18,700 tonnes in 1970, 18,352 tonnes in 1975 and, following adecline, approximately 28,526 individuals were killed between 1989 and 1997. Theaverage weight of C. maximus is 4 tonnes. As a result of conservation efforts, baskingshark fisheries have contracted considerably since the 1980s and again since 2000following the implementation of restrictions and bans on fishing for them or tradingin their products.However, hunting continues as part of the shark fin trade which is placing sharks atthreat throughout the world. Magnussen et al (2007) present “mounting evidence thatbasking sharks are being over-fished to supply the shark fin market”. They express theirconcern about the species’ vulnerability and the problems of identifying the species10


of origin in the market. Magnussen et al (2007) present the development andapplication of genetic forensic assays that do not need DNA sequencing but that canidentify the species of the fins being sold. They quote figures of $57,000 being paidfor a single basking shark fin which despite the world wide ban represents asignificant incentive for the illegal trade to continue. Doyle et al (2005) quote similarfigures and state that fins from Norwegian waters are the most expensive inSingapore thus underlining both the incentives to ignore the ban and the globalnature of the trade.2.5.1 Other threatsSims et al (2005), Doyle et al (2005), The Manx <strong>Basking</strong> <strong>Shark</strong> Watch (<strong>2009</strong>), theMarine Conservation Society (2005) and Speedie and Johnson (<strong>2009</strong>) identify bycatchfrom fishing effort, illegal shark fishing, boat strikes, entanglement, chemical pollution(heavy metals and the legacy of the anti fouling paint TBT) and marine litter as thecurrent threats. Climate change and pollution may have an impact on some feedspecies and alter ecological balances. Sims et al (2005) say that basking sharks sharethe vulnerability (late age of maturity and low fecundity) of other elasmobranchs tofishery exploitation and do not have the inherent capacity of boney fish to recovertheir populations.Bloomfield and Solandt (2007) note the possible threats (disruption of habitats,disruption of prey, disorientation due to electrical fields and increased possibilities ofboat strikes) to basking sharks resulting from the construction of offshore windfarms.Other disturbances noted by Doyle et al (2005) include naval sonar, offshoredevelopments, seismic testing and surveying, aggregate extraction, oil drilling andexploration. It is concluded that the extent of disturbance from all sources is difficultto evaluate as most incidences are not reported.The WISE scheme has been introduced to inform people about responsiblebehaviour in relationship to basking sharks and cetaceans. (Speedie and Johnson,<strong>2009</strong>). According to the Ulster <strong>Wildlife</strong> <strong>Trust</strong> <strong>Basking</strong> <strong>Shark</strong> Report 2004, basking11


sharks were seen as a nuisance because they damaged fishing gear and in 1938 theywere deliberately killed off Scotland as a result and even in 1998 an MP demandedaction on “the menace of basking sharks....”2.6 ConservationDoyle et al (2005) say: “Presently no estimates exist for the global or regional populationsize of basking sharks” but note their vulnerability to exploitation. As a result thebasking shark is assessed as “Vulnerable” (A1a,d,A2d) in the 2000 IUCN(International Union for Conservation of Nature) Red List and two subpopulations,North Pacific and North-East Atlantic were assessed as Endangered.The basking shark, C. maximus, has achieved significant status due to the activities ofinterested scientists and campaigning organisations in the UK such as the <strong>Shark</strong><strong>Trust</strong>, The Marine Conservation Society and the <strong>Wildlife</strong> <strong>Trust</strong>s.In the UK, basking sharks are recognised and named as a Biodiversity Action Plan(BAP) species. The Biodiversity action plan is the governments response to theConvention on Biological Diversity signed in 1992. It describes the UK’s biologicalresources and commits a detailed plan for the protection of identified resources.They are also protected in the UK waters up to 12 miles offshore by the <strong>Wildlife</strong>and Countryside Act.Internationally, C.maximus are also recognised and protected under CITES(Convention on International Trade in Endangered Species) Appendix II, CMS(Convention on Migratory Species) Appendix I and II, and Annex I of the UnitedNations Convention on the Law of the Sea (UNCLOS).To conclude, the protection afforded to basking sharks varies greatly around theworld. Though the killing of these sharks and trade in their products is banned inmany countries, there are still enough communities in the world who do not give thespecies protection. <strong>Basking</strong> sharks continue be seen as vulnerable and represent thefragility of species who, though protected, are seen as a valuable commodity in aworld with varying cultural attitudes to the natural world.12


2.7 Challenges to researchC. maximus, despite its large size spends most of its time out of the sight and, untilthe advent of satellite tags, many aspects of its behaviour and interactions with itsenvironment were based on conjecture. C. maximus does not offer the same ease ofspecies investigation as cetaceans. Cetaceans have to surface to breath, interact withpeople and some species can be kept in captivity. Nor has it, as in the case of majorprey species such as cod and herring, attracted the same attention from fisheriesresearch (Roberts, 2007). Interpretation of the natural history of the species is basedon a relatively small knowledge base. For instance, Speedie and Johnson (<strong>2009</strong>) andSims et al (2005) note that the only record of basking shark birth is from a paper bySund (1943), referring to an incident in 1936 when a female that was being towed toport gave birth to six pups. From this one incident a base length of pups at birth andthe number in a litter have been construed. As such the basking shark represents thechallenges of understanding oceanic and coastal natural history.Photo 4: <strong>Basking</strong> shark off Porthcurno 1971. Photo by Peter Heather13


Many aspects of the life history, population size and distribution of this shark remainrelatively unknown. This presents real problems when the question of conservationis considered. This is recognised by the many sources (such as Sims et al, (2005), andDoyle et al, (2005)) referenced in this work but makes it difficult to establish thehealth of the species and so relate it to biodiversity. If C. maximus is of use indetermining the status of biodiversity in coastal water, areas of continental shelf andin the open ocean, marine biologists and ecologists need to understand their lives,behaviour, distribution, and population. It could be concluded that their presenceindicates that the primary production of phytoplankton and hence zooplankton issufficient for them to feed. From that it can be assumed that these species areavailable for other species to feed on them as well and so up the trophic levels. Assuch C. maximus can be used as one of the indicators of the health of our seas.No more than a few hundred sharks are regularly seen in UK waters each summer,with sightings mainly restricted to the South West of England, the Isles of Man andthe west coasts of Scotland and Ireland. The species has been legally protected in theUK since 1999, however many sharks are thought to die as a result of injuriesinflicted though anthropogenic interference. Data collected to date suggests thatbasking shark entanglement in fishing gear in the Southwest could be on the increase.Since 2000, 21 dead basking sharks have been recorded in <strong>Cornwall</strong> by the <strong>Trust</strong>’sMarine Strandings Network. To date, it has been difficult to identify practicalmeasures to address these threats and ensure the survival and recovery of baskingshark in the UK seas. The <strong>Seaquest</strong> <strong>Basking</strong> <strong>Shark</strong> <strong>Project</strong> aims to improveprotection for basking sharks around <strong>Cornwall</strong> and the Isles of Scilly by collectingdata on basking shark distribution and behaviour, and the extent that threats such asfisheries bycatch, collision and recreation, pose to the species.14


3. MethodologyThe <strong>Seaquest</strong> <strong>Basking</strong> <strong>Shark</strong> Survey is a development of <strong>Seaquest</strong> Southwest, asightings scheme run jointly between <strong>Cornwall</strong> and Devon <strong>Wildlife</strong> <strong>Trust</strong>s for over10 years. This scheme encourages direct involvement of members of the public byasking them to report sightings of marine megafauna including dolphins, whales,basking sharks and turtles. <strong>Seaquest</strong> SW is closely associated with the The MarineStrandings Network (MSN) which is the official recorder for all marine strandings in<strong>Cornwall</strong>. Public recording schemes such <strong>Seaquest</strong> Southwest and the MarineStrandings Network are immensely important for basking shark research andconservation, as they provide long-term monitoring. However there are limitationsto the use of this data due to the lack of standardised survey methods and potentialmisidentification from untrained members of the public. To achieve the aims of this<strong>Project</strong> it was recognised during the 2008 survey that it was essential to recruit,train and support a team of sightings volunteers to conduct effort-based surveys forbasking sharks from the land to ensure such limitations were avoided. <strong>Seaquest</strong> SWand the MSN provide an important means by which the <strong>Wildlife</strong> <strong>Trust</strong> can involvepeople of all ages in learning about sea creatures and conservation issues as well asgathering important data.In 2008 the first <strong>Seaquest</strong> <strong>Basking</strong> <strong>Shark</strong> survey was carried out from Gwennap Headand Carn Gloose headland near Lands End, <strong>Cornwall</strong>, and involved over 70volunteers. The <strong>2009</strong> survey was based on the valuable lessons learned in the 2008survey.Following discussions with Seawatch Southwest who conducted effort based surveysfrom Gwennap Head in 2007 and 2008, it was agreed to work jointly with them in<strong>2009</strong> by the <strong>Trust</strong> providing the basking shark survey effort from 1/6/09 to 15/7/09(the commencement of the Seawatch SW survey).Following an inspection of the Gwennap Head site used by Seawatch Southwest by aTRUST officer and the volunteers’ coordinator, it was decided that the <strong>Trust</strong> couldnot use the site because of safety considerations. It was decided, however, that Hella16


Point to the east of Gwennap Head (labelled ‘Observational Position’ on Chart 1)was suitable and provided a comparable view of the survey site in that the field ofview was virtually identical and that the differences in elevation could be allowed for.It was felt that the Hella Point site would provide access to a wider range ofvolunteers as well as a greater opportunity to meet members of the public therebyincreasing general awareness of wildlife issues.Chart 1: The position of the Runnel Stone Reef.Hella Point was highlighted through previous sightings data as giving good views ofareas of increased basking shark activity (Speedie and Johnson, 2008). It hasuninterrupted views of the sea from the Lizard in the east, to the Scillies in the west,though weather conditions can frequently reduced the area visible from the site. TheRunnel Stone reef (see Chart 1) runs from the cliff base below the observation pointto the Runnel Stone buoy that marked its outer extent to the south. The reef isformed by a granite outcrop and has an uneven underwater profile. The flow overthe reef causes an area of disturbed water which can be assumed to be nutrient richas it is an area in which basking sharks appear, gannets feed and local inshore17


fishermen troll for bass and mackerel and set their lobster and crab pots. It may beassumed that the reef causes up-welling of water that augment frontal systems andso make it an area in which plankton growth is enhanced. The Runnel stone buoyand the Wolf Rock lighthouse, to the southwest, were used by the volunteers todetermine the distance of sightings and to estimate visibility.3.1 Recruitment of volunteersIn order to recruit volunteers required for the survey <strong>Cornwall</strong> <strong>Wildlife</strong> <strong>Trust</strong> issuedpress material, conducted radio interviews, sent e-mails to Cornish environmentalgroups and 2008 volunteers. The need for volunteers was published on the <strong>Trust</strong>’swebsite. Training was provided in two forms. Firstly on 16 th May <strong>2009</strong> a trainingevent was held at the Dive Club in Penzance and at the survey site at Hella Point.The second form of training was provided, as required on site, to new volunteerswho joined the survey after the 16 th May.38 potential volunteers attended the main training day, many of whom subsequentlyparticipated in the survey. Many other people expressed interest in the survey. Theywere contacted and provided with appropriate information.All volunteers were provided with a folder containing comprehensive informationabout the survey, the species of interest, identification guides, health and safetyissues and recording procedures.18


Photo 5: Volunteers at Hella Point. Photo by Mike LangshawDuring the course of the survey it became apparent that the information could beimproved with the provision of “all weather” laminated information sheets.Throughout the survey volunteers were kept up to date with the progress of thesurvey, in particular the need for support to fill the rota. It had been intended toprovide an on line regular update of sightings but this did not happen due to lack ofresources.3.2 Volunteer managementVolunteer surveys were coordinated by a volunteer coordinator (Mike Langshaw)who took sole responsibility for making sure surveys went smoothly and that therewere enough volunteers to complete all surveys. This role included many hours oflogistical planning as well as gap filling if there was a survey shift with too fewvolunteers. During the period of the survey this coordination role amounted to a fulltime role due to the number of volunteers involved. <strong>Cornwall</strong> <strong>Wildlife</strong> <strong>Trust</strong> wouldlike to take this opportunity to thank Mike for all his tireless work which made thisproject possible.19


ehaviour and movement. Volunteers were asked to take photographs of thesightings, as this could aid identification.Photo 7: <strong>Basking</strong> shark off Gwennap Head <strong>2009</strong>. Photo by Nigel WardHowever it was recognised that the identification of individual sharks was notgenerally possible unless they were very close to the site. Fin identification is moresuccessful on boat based surveys where observers are able to gain greater proximity.Volunteers were also asked to record any issues concerning harassment ordisturbance to marine life, as this would assist in warning and educating thoseconcerned.NB sightings of basking sharks were not taken in winds in excess of Force 6 as waveconditions would make accurate recording difficult. A number of days were lost dueto bad weather.3.4 Health and safety considerationsHealth and safety was a major consideration given the length of time spent at thelocation each day as previously noted. The <strong>Trust</strong> decided that for health and safetyreasons the Gwennap Head site was not suitable for the <strong>Seaquest</strong> volunteers. Eachvolunteer had to be over 16 years of age due to the cliff-top location of each survey.21


Once at the location each volunteer read and signed a disclaimer that outlined thehealth and safety issues, the facilities available at the site and what to do in anemergency. A database was complied containing information on each volunteer,including details such as their home address, next of kin’s details and allergies, all incase of an emergency. Mobile phone contact was possible from the survey site. Loneworking was not encouraged but became essential, particularly in the latter stages ofthe survey when volunteer recruitment and retention became more of an issue.Photo 8: <strong>Basking</strong> shark with surfers off Porthleven <strong>2009</strong>. Photo by Andy Morse22


4. ResultsA total of 64 volunteers took part in the <strong>Seaquest</strong> <strong>Basking</strong> <strong>Shark</strong> <strong>Project</strong> <strong>2009</strong>. Therewere 5 full days and 25 half day sessions on which no survey took place due to poorweather or lack of volunteers. A majority of these days were in August when baskingshark activity was relatively low.Photo 9: <strong>Seaquest</strong> <strong>Basking</strong> <strong>Shark</strong> <strong>Project</strong> volunteers at Hella Point site <strong>2009</strong>.Photo by Abby CrosbyOther marine mega fauna recorded included all species in table 1 and many birdspecies not listed.Throughout the survey period, two methods of displaying basking shark numberswere used - the daily peak (the number of shark seen at any one half hour sweepacross the survey area) (Figure 1) and the total daily sightings (all the sightings seenin all the half hour sweeps in a day) (Figure 2). Both these figures demonstrate thatactivity for basking sharks was at a peak during June and early July. Sighting numberswent down dramatically during July and August. Incidental sighting reports to23


<strong>Seaquest</strong> Southwest received during the early July indicated that sharks were evidentoff the north coast, particularly in the Newquay area (Figures 1 and 2).SpeciesTotal number recordedCommon dolphin 71Grey seal 48Harbour porpoise 35Bottlenose dolphin 15Unidentified cetaceansp. 13Ocean sunfish 12Rissos dolphin 5Leatherback turtle 2Minke whale 2Fin whale 1Table 1: Sightings of other marine wildlife during basking shark watchFigures 3-14 show the number of sightings against the tidal height per half hoursweep. This data is inconclusive regarding a connection between the peak tidal stateand sightings, but it is felt that sharks are influenced by tide. The figures used forplotting for tidal cycle comparison were chosen using the days with large numbers ofsightings. Though no conclusions can be drawn form the tidal data comparison, thereare several interesting trends within the data which we hope will become moreconclusive with the addition of next years data.A number of dive boats were seen in the area and one dive group reported seeingbasking sharks “stacked” underwater as they fed in a gully off Logan’s Rock, to theeast of the survey sight, thus indicating that sharks were feeding throughout thewater column. Distribution through the water column could mean that thebathymetric topography has an important role to play along with the tidal cycle, asunderwater obstacles will produce peaks of flow rate at different times through thetidal cycle.24


4.1 Incidental and historical observationsLocal fishermen recalled seeing large aggregations of sharks in the past few decadesand said that there had been occasions when they decided not to launch their boatsfor fear of being sunk as so many sharks were breaching. It is interesting to notethat these fishermen said that they used to refer to common dolphin as porpoisesanimportant piece of information when historical/anecdotal information is reviewed.Eco tour boats were evident throughout the survey period but the poor weatherconditions meant that they did not see many sharks and so were not effective as“pointers” for the watchers.Photo 10: <strong>Basking</strong> shark with local boat interest. Photo by Andy Morse25


Peak number of surface sightings3530252015105027-May 16-Jun 06-Jul 26-Jul 15-Aug 04-Sep 24-SepMonthNumber of<strong>Shark</strong>sFigure 1: Graph displaying the daily peak basking shark surface sightings from June to August <strong>2009</strong>26


Number of surface sightings270240210180150120906030001/06/<strong>2009</strong> 01/07/<strong>2009</strong> 01/08/<strong>2009</strong>MonthNumberof<strong>Shark</strong>sFigure 2: Total number of sharks sighted per day27


Number of <strong>Shark</strong>sNumber of sharks181614121086420Number of <strong>Shark</strong>s3530252015105030252015105005:3006:0006:3007:0007:3008:0008:3009:0009:3010:0010:3011:0011:3012:0012:3013:0013:30Time14:0014:3015:0015:3016:0016:3017:0017:3018:0018:3019:0019:3020:0020:30Figure 3: Graph displaying number of basking shark surface sightings in relation to tidalmovementon 1st June <strong>2009</strong>05:3006:0006:3007:0007:3008:0008:3009:0009:3010:0010:3011:0011:3012:0012:3013:0013:30Time14:0014:3015:0015:3016:0016:3017:0017:3018:0018:3019:0019:3020:0020:30Figure 4: Graph displaying number of basking shark surface sightings in relation to tidalmovement2nd June <strong>2009</strong>05:3006:0006:3007:0007:3008:0008:3009:0009:3010:0010:3011:0011:3012:0012:3013:0013:30Time14:0014:3015:0015:3016:0016:3017:0017:3018:0018:3019:0019:3020:0020:30Figure 5: Graph displaying number of basking shark surface sightings in relation to tidalmovement –3rd June <strong>2009</strong>54.543.532.521.510.5054.543.532.521.510.50Tide height (m)Tide height (m)54.543.532.521.510.50Tide height (m)numbertide heightnumbertide heightNumberTide height28


Number of sharksNumber of <strong>Shark</strong>s10987654321098765432103005:3006:0006:3007:0007:3008:0008:3009:0009:3010:0010:3011:0011:3012:0012:3013:0013:30Time14:0014:3015:0015:3016:0016:3017:0017:3018:0018:3019:0019:3020:0020:306543210Tide height (m)NumberFigure 6: Graph displaying number of basking shark surface sightings in relation to tidalmovement6th June <strong>2009</strong>05:3006:0006:3007:0007:3008:0008:3009:0009:3010:0010:3011:0011:3012:0012:3013:0013:30Time14:0014:3015:0015:3016:0016:3017:0017:3018:0018:3019:0019:3020:0020:306543210Tide height (m)Tide height (m)NumberFigure 7: Graph displaying number of basking shark surface sightings in relation to tidalmovement –7th June <strong>2009</strong>6Tide height (m)Number of <strong>Shark</strong>s252015105005:3006:0006:3007:0007:3008:0008:3009:0009:3010:0010:3011:0011:3012:0012:3013:0013:30Time14:0014:3015:0015:3016:0016:3017:0017:3018:0018:3019:0019:3020:0020:30Figure 8: Graph displaying number of basking shark surface sightings in relation to tidalmovement –9th June <strong>2009</strong>543210Tide height (m)NumberTide height29


Number of sharksNumber of <strong>Shark</strong>sNumber of sharks9876543210987654321043.532.521.510.5005:3006:0006:3007:0007:3008:0008:3009:0009:3010:0010:3011:0011:3012:0012:3013:0013:30Time14:0014:3015:0015:3016:0016:3017:0017:3018:0018:3019:0019:3020:0020:30Figure 9: Graph displaying number of basking shark surface sightings in relation to tidalmovement12th June <strong>2009</strong>05:3006:0006:3007:0007:3008:0008:3009:0009:3010:0010:3011:0011:3012:0012:3013:0013:30Time14:0014:3015:0015:3016:0016:3017:0017:3018:0018:3019:0019:3020:0020:30Figure 10: Graph displaying number of basking shark surface sightings in relation to tidalmovement –13th June <strong>2009</strong>05:3006:0006:3007:0007:3008:0008:3009:0009:3010:0010:3011:0011:3012:0012:3013:0013:30Time14:0014:3015:0015:3016:0016:3017:0017:3018:0018:3019:0019:3020:0020:30Figure 11: Graph displaying number of basking shark surface sightings in relation to tidalmovement –14 June <strong>2009</strong>654321054.543.532.521.510.50Tide height (m)Tide height (m)54.543.532.521.510.50Tide height (m)NumberTide heightNumberTide heightNumberTide height30


Number of <strong>Shark</strong>sNumber of <strong>Shark</strong>sNumber of <strong>Shark</strong>s4.543.532.521.510.5043.532.521.510.50987654321005:3006:0006:3007:0007:3008:0008:3009:0009:3010:0010:3011:0011:3012:0012:3013:0013:30Time14:0014:3015:0015:3016:0016:3017:0017:3018:0018:3019:0019:3020:0020:30Figure 12: Graph displaying number of basking shark surface sightings in relation to tidalmovement –16th June <strong>2009</strong>05:3006:0006:3007:0007:3008:0008:3009:0009:3010:0010:3011:0011:3012:0012:3013:0013:30Time14:0014:3015:0015:3016:0016:3017:0017:3018:0018:3019:0019:3020:0020:30Figure 13: Graph displaying number of basking shark surface sightings in relation to tidalmovement –26th June <strong>2009</strong>05:3006:0006:3007:0007:3008:0008:3009:0009:3010:0010:3011:0011:3012:0012:3013:0013:30Time14:0014:3015:0015:3016:0016:3017:0017:3018:0018:3019:0019:3020:0020:30Figure 14: Graph displaying number of basking shark surface sightings in relation to tidalmovement –28th June <strong>2009</strong>54.543.532.521.510.5065432106543210Tide height (m)Tide height (m)Tide height (m)NumberTide heightNumberTide heightNumberTide height31


5. DiscussionThis discussion will focus on two areas. Firstly it will look at the data collectedrelating to basking sharks. Secondly it will explore the lessons learned for the <strong>Trust</strong>in establishing and managing the survey.During the <strong>2009</strong> survey there was a significant peak in sightings at the beginning ofJune reflected in the 30 minute records of sightings and maximum daily sightings- seefigures 1 and 2.In <strong>2009</strong> the pattern of sightings in the early summer were in line with expectationsand reflected the bloom in plankton population and the formation of frontal systems(Sims et al, 1997). <strong>Shark</strong>s had been recorded by ad hoc public observations as earlyas March <strong>2009</strong> and it would have been interesting to have been recording from HellaPoint from an earlier date than the 1 st June. By August sharks were being sightedagain but not in significant numbers.The <strong>2009</strong> survey recorded more sea surface sightings of sharks than 2008 when only26 were seen from Carn Gloose during the whole three month survey. The sum ofmaximum daily sightings for <strong>2009</strong> was 208. This is the preferred method of reachinga total that can be used comparatively with other years as it eliminates doublecounting but probably results in an under estimation of numbers as individuals movethrough the survey area during the watch period. Some experienced shark observersestimate that for every shark recorded on the surface there are four in the waterbelow.The debate concerning recording methods and the reliability of the results obtainedfrom shore based observations underlines the challenges in obtaining informationabout the basking shark. 2006 saw many sharks around the Cornish coastthroughout the summer however they were largely absent in the proceeding yearsleading people to conclude that there had been a population shift to the northernwaters around the British Isles. In September 2007 an aggregation of between 300and 400 sharks were seen off Sennen Cove- but this was not scientifically verified.32


Local fishermen reported that large aggregations have been sighted in the past andsuggest that though numbers have increased recently they are not as numerous asthey were 40 years ago. This anecdotal information could be seen as a reflection ofthe impact of the basking shark fishery and its subsequent banning in Europeanwaters.It could be expected that sightings would reflect the daily tidal cycle as the tidalcurrent forced nutrients and plankton over and around the Runnel Stone reef. The12 graphs (figures 3-14) provide representations of sightings against the daily tidalcycle. The graphs for the 1 st , 2 nd 3 rd and 6 th of June show that most sightings occurredaround low water when tidal flow would be relatively low. However this pattern isnot repeated with the graph for the 9 th June showing aggregations of sharks beingseen on the rising tide and the 16 th June showing a falling tide preference. Inconclusion there is insufficient evidence to demonstrate that there is a strongcorrelation between the tidal cycle/movement and surface sightings in the surveylocation. It could be suggested that evidence of sub surface activity woulddemonstrate a link. A local fisherman suggested that peak surface sightings occurredeither side of high tide.The impact of the Runnel Stone reef on tidal flow can be easily observed from theshore as masses of seawater is forced over the granite formation causing significantturbulence. It was beyond the scope of the survey to make any detailed observationsof the impact of the reef. It was noted that there appeared to be a counter currentunder Hella Point that flowed to the west on the flood tide. This area appeared tobe favoured by basking sharks and gannets.There were 6 recorded incidents of basking sharks breaching. This was evident fromthe beginning of the survey during which time there were public reports fromaround the Cornish coast of this behaviour. It is not possible to determine whetheror not these reports and sightings represent an increase in breaching as effort baseddata does not exist for previous years. It was noted that sharks were seen breaching2 or 3 times in succession and that they were not always associated with groups ofother sharks visible on the surface.33


Sightings of other marine megafauna (Table 1) show a significant range of megafaunarecorded and in quite large numbers, with the most frequently seen species beingthe common dolphin.There was no discernable link between basking sharks being observed on the surfaceand sightings of other marine mega fauna.Weather impacts, frontal systems and plankton biomass can all be expected to haveconsiderable influence on the probability of sighting basking sharks from Hella Point.Sophisticated data of this sort is not readily available and it was beyond the scope ofthis survey to obtain it. However, the continuation of such surveys and collation ofthe data may help in our understanding in future years.5.1 Critique of Survey MethodThe main object of the survey was to observe and record basking sharks. Mostvolunteers felt happiest using their naked eyes and binoculars as this allowed them toscan the largest area of sea. Many found that binoculars caused less eye strain. Moreexperienced observers made much greater use of scopes.The scope was generally used to focus in on observed animals but some peoplefound it hard to locate a shark using this equipment. Others used the scope to greateffect by concentrating on a reduced area of water.<strong>Seaquest</strong> volunteers frequently worked alone. It may be assumed that lone workerswere less able to maintain concentration and did not have the stimulation ofcompany though our volunteers often stated that they enjoyed being alone.5.2 Critique of Recording MethodThe reporting methods/formats employed were those that had been used inprevious surveys however the forms had been modified (increase in font etc) to34


make them easier to use. Observers recorded sharks at 30 minute intervalsundertakinga sweep of the area and counting those sharks that were visible. Thisprocess was designed to reduce double counting and reflected the fact thataggregations of sharks tend to remain in the area for extended periods. Aspreviously stated it is also argued that during a 15 hour observation period sharkscould be expected to move in and out of the area. However this method was noteffective when there were few sharks – on these occasions volunteers recordedwhat they saw during the 30 minute periods. Recording of other species was basedon each sighting. Monitoring of the seal haul out below Gwennap Head was carriedout until mid July but proved difficult because of the distance to the observation siteand a reluctance to leave equipment unattended at Hella point. As a result the datacollected was of varying quality.With so many volunteers, recording styles varied considerably as did confidence indetermining factors such as the distance of sighted animals from the observationposition.A laminated set of example forms could have led to more consistent recording.Feedback from volunteers suggested other laminated information, laminated sheetsre: sea state, cloud cover, visibility, tide times and wind strength would have beenbetter than sodden sheets attached to the clip board and would have madeconsistent recording of conditions possible. It has been noted that recordingrequires more attention as a training need.5.3 Anthropogenic impactsThere were some reports of possible harassment by people wanting to photographsharks in the water in the first week of the survey but during the period as a wholethere appeared to be no apparent impact by people on the species being observed.Fishermen were frequently working the Runnel Stone reef for mackerel and bass butdid not interact with the sharks or cetaceans. As previously noted Galpin, J.(<strong>2009</strong>)suggests that basking sharks have different responses to disturbance at different35


times of the year depending on their activities, particularly in relationship tocourtship. He suggests that they are more vulnerable to disturbance during thebeginning of the “sighting season”. As a consequence it could be suggested that ecotour operators take extra care at these times. However the role of eco touroperators in informing and inspiring the public and hence furthering the conservationagenda is recognised. Apart from one incident which had the potential to disturb thesharks there was no evidence of anthropogenic pressure in the survey area5.4 Media issuesThe <strong>Basking</strong> <strong>Shark</strong> Survey received a lot of media attention from live breakfast timetelevision broadcasts, news reports, radio interviews and newspaper articles. Themedia interest raised the profile of the project and the associated marineconservation issues. During the survey it was noted that members of the public had akeen interest in the marine environment and were particularly fascinated by baskingsharks and cetaceans. The importance of the accessibility to the public whilstundertaking the survey is underlined by the experience of volunteers in 2008 and<strong>2009</strong>.It became clear that as a “flagship species” the basking shark has the ability tocapture the public’s imagination and resulted in a steady stream of visitors to thesite. From the project’s point of view informing the public had a high priority but itwas recognised that media “hype” can result in a lack of accuracy/exaggeration and amove away from scientific objectivity.However, the <strong>Trust</strong> valued the media interest received in 2008 and <strong>2009</strong> andbelieves that it did much to add to the success of the project in meeting its broadconservation objectives.In conclusion, this project proved a successful continuation of the work undertakenin 2008. Over the three months of the survey we collected interesting data,observational reports and engaged many people in the process as volunteers or asinterested members of the public.36


6. Conclusions and recommendations6.1 RecruitmentRecruitment was in response to emails to individual people and organisations and tomedia interest. Despite a paucity of sightings in July and August, very few watcheswere lost though many were conducted by people working alone. A detailed contactlist of volunteers has been compiled.6.2 TrainingThe training day in May was well attended and most people who were there went onto take part in the survey. However, the majority of the volunteers did not attendthe training day and received on site training. Generally this proved successful.However instruction/ information/ feedback regarding recording could be improved.Laminated sample recording forms etc as suggested (see Discussion) and betterguidance regarding the use of binoculars and scopes should be provided.6.3 Site LocationHella Point proved a good observation position though in strong winds and rain itcould be difficult to find shelter. Access from the car park, with its toilets and cafe atPorthgwarra was good. However the drive to Porthgwarra was difficult on occasionsdue to holiday traffic. Many volunteers drove significant distances so journey timeswere long. Volunteers were not paid expenses (fuel, parking etc), a factor thatdeterred some. Some volunteers travelled from beyond <strong>Cornwall</strong> to take part,camping or using B+B. The <strong>Wildlife</strong> <strong>Trust</strong> is indebted to all the volunteers for thework they did during the summer.Consideration could be given to reducing the “sweep of observation” from 180° to90° or 45° as advocated by Galpin (<strong>2009</strong>). A reduction in sweep would result inmore focus on a specific area of sea but would be hard to monitor and could lead to37


valuable information not being recorded. It could also mean that, in strong sunlight,the sweep area would be hard to monitor at certain times of the day.6.4 MethodologyIt is concluded that the methods used during the <strong>2009</strong> survey were more thanadequate to meets the aims and objectives of the project.6.5 Observation PeriodIn 2008 and <strong>2009</strong> the survey has taken place in June, July and August. This means thatperiods of shark activity in May, September and October were missed whilst July andAugust (when observations can be expected to be low) were included. It is a tributeto the volunteers that they continued to participate despite the lack of sightingsduring most of the survey. An earlier start could obtain valuable data at the time ofthe spring/summer plankton bloom, particularly with respect to courtship behaviour.Similarly a resumption of the survey in September could cover the late summerbloom. Liaison with other organisations (National Coastwatch Institute, RNLILifeguard) could mean that the <strong>Trust</strong> could be alerted to basking shark activity inJuly/August . The <strong>Trust</strong> need to decide whether to continue over the same period as2008/09 with the advantage of comparable data or seek to observe the maximumnumber of sharks.6.6 PublicityIt is important that the <strong>Trust</strong> engages with the media so as to educate the public,recruit members and further the conservation agenda. It is suggested that the <strong>Trust</strong>starts planning for media interest at an early stage so that it is less reactive andretains as much control as is possible. Regular bulletins on the <strong>Trust</strong>’s website givingsightings up-dates were anticipated in <strong>2009</strong> but unfortunately time was not available.It is suggested that this should be addressed for 2010.38


Finally, <strong>Cornwall</strong> <strong>Wildlife</strong> <strong>Trust</strong> wishes to recognise the success of the<strong>2009</strong> survey and to thank all those who took part and supported ourefforts.Photo 11: Volunteers on training day. Photo by Abby Crosby39


7. ReferencesBloomfield, A and Solandt,J-L. (2007) The Marine Conservation Society <strong>Basking</strong> <strong>Shark</strong>Watch 20-year report (1987-2006).Compagno, L. Dando, M and Fowler, S.(2005)Collins Field Guide: <strong>Shark</strong>s. London.Collins.Doyle, J. Solandt, J-L, Fanshawe, S. Richardson, P and Duncan, C. (2005) <strong>Basking</strong><strong>Shark</strong> Watch Report 1987-2004.Ross-on-Wye. Marine Conservation Society.Galpin, J. (<strong>2009</strong>) Contributor at the “<strong>Basking</strong> <strong>Shark</strong>s- a Global Perspective”Conference Isle of Man <strong>2009</strong>.Gore, M. Rowat, D. Hall, J. Gell, F. And Ormond, R. (2008). Transatlantic migrationand deep mid-ocean diving by basking shark. Biological Letters.4,395-398.Hardy, A.(1959)The Open Sea:Fish and Fisheries, New Naturalist37.London.Collins.Lawton,J.(1991) Are species useful? Oilos.62,3-4.Mac Cullagh, R.(1992)The Irish Currah Folk.Dublin. Wolfhound Press.Magnussen, J. Pikitch, E. Clarke, S. Nicholson, C. Hoelzel A and Shivji, M. (2007)Genetic tracking of basking shark products in international trade.Animal Conservation.10.199-207.Manx <strong>Basking</strong> <strong>Shark</strong> Watch www.manxbaskingsharkwatch.com accessed 20/03/09McGonigle, M (2008) Oil and Water-18 th Century Whale and <strong>Basking</strong> <strong>Shark</strong> Fisheries ofDonegal Bay, Ireland. The International Journal of Nautical Archaeology.37.2:302-312Natural England Research Information Note RIN018 (2008)www.intute.ac.uk/healthandlifesciences/cgi Accessed 30/8/0840


Open University S180 Life in the ocean: exploring our blue planet.2002Roberts, C. (2007) The Unnatural History of the Sea; The past and future of humanityand fishing. London. Gaia.Wallace,S and Gisborne, B. (2006). <strong>Basking</strong> sharks: the slaughter of BC’s gentlegiants”.Vancover.Transmontanus.<strong>Shark</strong> <strong>Trust</strong>: www.baskingsharks.org/view accessed 20/03/09Sims, D and Reid, P. (2002)Congruent trends in long-term zooplankton decline in thenorth-east Atlantic and basking shark (Cetorhinus maximus) fishery catches off west Ireland.Fisheries Oceanography. 11,1:59-63.Sims, D. Southall, E. Metcalfe, J and Pawson,M. (2005) <strong>Basking</strong> <strong>Shark</strong> Assessment: Final<strong>Project</strong> Report for global <strong>Wildlife</strong> Division of the Department for Environment, Food andRural Affairs. London. Defra.Sims, D. Southall, E. Richardson, J. Reid, P and Metcalfe, J. (2003) Seaonal movementsand behaviour of basking sharks from archival tagging: no evidence of winter hibernation.Marine Ecology Progress series. 248: 187-196.Solandt, J.(2008) Marine Local Biodiversity Action Plan Guidance Manual for England. TheMarine Conservation Society.Southall, E. Sims, D. Metcalfe, J. Doyle, J. Fanshawe, S.Lacey, C. Shrimpton, J. Solandt,J-L. Speedie, C. (2005) Spatial distribution patterns of basking sharks on the Europeanshelf: preliminary comparison of satellite-tag geolocation, survey and public sightings data.Journal of the Marine Biological Association of the UK. 85: 1083-1088Speedie, C and Johnson, L. (2008) The <strong>Basking</strong> <strong>Shark</strong> (Cetorhinus maximus) in West<strong>Cornwall</strong>. Natural England Research Report NERR01841


Sund, O.(1943) Et brugdebarselNaturen. 67:285-286..UK Biodiversity Action Plan website. www.ukbap.org.uk accessed 8/5/09WiSe scheme www.wisescheme.orgwww.fao.org/fishery/species/ accessed 19/03/09www.mcsuk.org/acatalog/Marine_Conservation Accessed 9/5/0942

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!