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Diet of the harbour seal (Phoca vitulina vitulina) in the west and south-west of Ireland

Published online by Cambridge University Press:  23 June 2010

Ailbhe S. Kavanagh ,
Michelle A. Cronin ,
Mike Walton  and
Emer Rogan
Ailbhe S. Kavanagh*
Affiliation:
Zoology, Ecology & Plant Science Department, University College Cork, Distillery Fields, North Mall, Cork City, Ireland
Michelle A. Cronin
Affiliation:
Coastal & Marine Resources Centre, ERI, University College Cork, Naval Base, Haulbowline, Cobh, County Cork, Ireland
Mike Walton
Affiliation:
Sea Mammal Research Unit, University of St Andrews, St Andrews, Fife KY16 8LB, Scotland, UK
Emer Rogan
Affiliation:
Zoology, Ecology & Plant Science Department, University College Cork, Distillery Fields, North Mall, Cork City, Ireland
*
Correspondence should be addressed to: A.S. Kavanagh, Zoology, Ecology & Plant Science Department, University College Cork, Distillery Fields, North Mall, Cork City, Ireland email: [email protected]
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Abstract

Although the harbour seal (Phoca vitulina vitulina) is relatively common in coastal waters of the Republic of Ireland, it remains largely unstudied. Issues including potential interactions with coastal fisheries and the occurrence of phocine distemper virus outbreaks in 1988 and 2002 have highlighted the need to increase our knowledge of the ecology of these animals. The diet of harbour seals was investigated using a combination of approaches: hard-part analysis of scat contents and fatty-acid analysis. A total of 102 scat and 13 blubber samples were collected from two locations in Ireland and were analysed following standard methodologies. Results from scat analysis indicate that the seals are opportunistic, generalist feeders, and probably consume prey in relation to its availability. Eighteen prey species were identified, with sandeels (Ammodytidae spp.) constituting 55% of the prey items by number. Biomass of prey was reconstructed using otolith-length regression equations, with and without the application of digestion correction factors and sole (Solea solea) (16.1%), sandeels (15.2%), and Trisopterus species (12.4%) were found to be the most important species by weight. Rarefraction curves were used to determine prey species diversity on a sample site basis and we used accumulation curves to ascertain whether sampling was sufficient on a site basis. Sixty-four fatty acids were isolated from the blubber and analysis of the fatty-acid profiles revealed the possible influence of season, seal weight and sex on the seals' long-term diet. Some of the prey species recorded in the diet overlap with commercially and recreationally caught fish species in Ireland; however, there was little overlap with marketed size-ranges.

Keywords

harbour sealdietscatsfatty-acidsRepublic of Ireland
Type
Research Article
Information
Journal of the Marine Biological Association of the United Kingdom , Volume 90 , Special Issue 8: Marine Mammals , December 2010 , pp. 1517 - 1527
Copyright
Copyright © Marine Biological Association of the United Kingdom 2010

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References

REFERENCES

Anderson, S.M., Lydersen, C., Grahl-Nielsen, O. and Kovacs, K.M. (2004) Autumn diet of the harbour seal (Phoca vitulina) at Prins Karls Forland, Svalbard, assessed via scat and fatty-acid analyses. Canadian Journal of Zoology 82, 1230–1245.CrossRefGoogle Scholar
Berrow, S.D., O'Neill, M. and Brogan, D. (1998) Discarding practices and marine mammal bycatch in the Celtic Sea herring fishery. Biology and environment. Proceedings of the Royal Irish Academy 1, 1–8.Google Scholar
Brown, E.G. and Pierce, G.J. (1998) Monthly variation in the diet of harbour seals in inshore waters along the southeast Shetland (UK) coastline. Marine Ecology Progress Series 167, 275–289.CrossRefGoogle Scholar
Campana, S.E. (2004) Photographic atlas of the fish otoliths of the northwest Atlantic Ocean. Canadian Special Publication of Fisheries and Aquatic Sciences 133. Ottawa: NRC Research Press, pp. 284.CrossRefGoogle Scholar
Clarke, M.R. (ed.) (1986) A handbook for the identification of cephalopod beaks. Oxford: Clarendon Press, pp. 273.Google Scholar
Colwell, R.K. (2005) EstimateS: Statistical estimation of species richness and shared species from samples. Version 8.0. User's guide and application. Published at: http://purl.oclc.org/estimates.Google Scholar
Costello, M.J. (1990) Predator feeding strategy and prey importance: a new graphical analysis. Journal of Fish Biology 36, 261–263.CrossRefGoogle Scholar
Cronin, M., Duck, C., Ó'Cadhla, O., Nairn, R., Strong, D. and O'Keeffe, C. (2007) An assessment of population size and distribution of harbour seals in the Republic of Ireland during the moult season in August 2003. Journal of Zoology 273, 131–139.CrossRefGoogle Scholar
Cronin, M.A., Kavanagh, A. and Rogan, E. (2008) The foraging ecology of the harbour seal (Phoca vitulina vitulina) in Ireland. Final Report to the Marine Institute. Project ST05/12, pp. 145.Google Scholar
Folch, J., Less, M. and Slone Stanley, G.H. (1957) A simple method for the isolation and purification of total lipids from animal tissues. Journal of Biological Chemistry 226, 497–509.CrossRefGoogle ScholarPubMed
FSS Stock Book (2006) Annual review of fish stocks in 2006 with management advice for 2007. Marine Institute, Dublin, Marine Fisheries Services Division.Google Scholar
FSS Stock Book (2007) Annual review of fish stocks in 2007 with management advice for 2008. Marine Institute, Dublin, Marine Fisheries Services Division.Google Scholar
Gotelli, N.J. and Colwell, R.K. (2001) Quantifying biodiversity: procedures and pitfalls in the measurement and comparison of species richness. Ecology Letters 4, 379–391.CrossRefGoogle Scholar
Harding, K.C., Härkönen, T. and Caswell, H. (2002) The 2002 European seal plague: epidemiology and population consequences. Ecology Letters 5, 727–732.CrossRefGoogle Scholar
Härkonen, T.J. (1986) Guide to the otoliths of the bony fishes of the Northeast Atlantic. Hellerup, Denmark: Danbiu, 256 pp.Google Scholar
Härkonen, T.J. (1987) Seasonal and regional variations in the feeding habits of the harbour seal, Phoca vitulina, in the Skagerrak and the Kattegat. Journal of Zoology (London) 213, 535–543.CrossRefGoogle Scholar
Härkonen, T., Dietz, R., Reijnders, P., Teilmann, J., Harding, K., Hall, A., Brasseur, S., Siebert, U., Goodman, S.J., Jepson, P.D., Dau Rasmussen, T. and Thompson, P. (2006) A review of the 1988 and 2002 phocine distemper virus epidemics in European harbour seals. Diseases of Aquatic Organisms 68, 115–130.CrossRefGoogle ScholarPubMed
Harwood, J. and Croxall, J.P. (1988) The assessment of competition between seals and commercial fisheries in the North Sea and the Antarctic. Marine Mammal Science 4, 13–33.CrossRefGoogle Scholar
Iverson, S.J., Field, C., Bowen, W.D. and Blanchard, W. (2004) Quantitative fatty acid signature analysis: a new method of estimating predator diets. Ecological Monographs 74, 211–235.CrossRefGoogle Scholar
Iverson, S.J., Frost, K.J. and Lowry, L.F. (1997) Fatty acid signatures reveal fine scale structure of foraging distribution of harbour seals and their prey in Prince William Sound, Alaska. Marine Ecology Progress Series 151, 255–271.CrossRefGoogle Scholar
Jemison, L.A., Pendleton, G.W., Wilson, C.A. and Small, R.J. (2006) Long-term trends in harbour seal numbers at Tugidak Island and Nanvak Bay, Alaska. Marine Mammal Science 22, 339–360.CrossRefGoogle Scholar
Learmonth, J.A. (2006) Life history and fatty-acid analysis of harbour porpoises (Phocoena phocoena) from Scottish waters. PhD thesis. University of Aberdeen, Scotland, pp. 293.Google Scholar
Lockley, R.M. (1966) The distribution of grey and common seals on the coasts of Ireland. Irish Naturalists' Journal 15, 136–143.Google Scholar
Lonergan, M., Duck, C.D., Mackey, B.L., Cunningham, L. and Boyd, I.L. (2007) Using sparse survey data to investigate the declining abundance of British harbour seals. Journal of Zoology 271, 261–269.CrossRefGoogle Scholar
Mathews, E.A. and Pendleton, G.W. (2006) Declines in harbour seal (Phoca vitulina) numbers in Glacier Bay national park, Alaska, 1992–2002. Marine Mammal Science 22, 167–189.CrossRefGoogle Scholar
Olesiuk, P.F., Bigg, M.A. and Ellis, G.M. (1990) Recent trends in the abundance of harbour seals, Phoca vitulina, in British Columbia. Canadian Journal of Fisheries and Aquatic Sciences 47, 992–1003.CrossRefGoogle Scholar
Pierce, G.J. and Boyle, P.R. (1991) A review of methods for dietary analysis in piscivorous marine mammals. Oceanography and Marine Biology: an Annual Review 29, 409–486.Google Scholar
Pierce, G.J. and Santos, M.B. (2003) Diet of the harbour seals (Phoca vitulina) in Mull and Skye (Inner Hebrides, western Scotland). Journal of the Marine Biological Association of the United Kingdom 83, 647–650.CrossRefGoogle Scholar
Pierce, G.J., Thompson, P.M., Miller, A., Diack, J.S.W., Miller, D. and Boyle, P.R. (1991) Seasonal variation in the diet of common seals (Phoca vitulina) in the Moray Firth area of Scotland. Journal of Zoology (London) 223, 641–652.CrossRefGoogle Scholar
Pierce, G.J., Santos, M.B. and Cerviño, S. (2007) Assessing sources of variation underlying estimates of cetacean diet composition: a simulation study on analysis of harbour porpoise diet in Scottish (UK) waters. Journal of the Marine Biological Association of the United Kingdom 87, 213–221.CrossRefGoogle Scholar
Pitcher, K.W. (1990) Major decline in number of harbour seals, Phoca vitulina richardsi, on Tugidak Island, Gulf of Alaska. Marine Mammal Science 6, 121–134.CrossRefGoogle Scholar
Prime, J.H. and Hammond, P.S. (1990) The diet of grey seals from the southwestern North Sea assessed from analysis of hard parts in faeces. Journal of Applied Ecology 27, 435–447.CrossRefGoogle Scholar
Ridoux, V., Spitz, J., Vincent, C. and Walton, M.J. (2007) Grey seal diet at the southern limit of its European distribution: combining dietary analysis and fatty acid profiles. Journal of the Marine Biological Association of the United Kingdom 87, 255–264.CrossRefGoogle Scholar
Rogan, E., Penrose, R., Gassner, I., Mackey, M.J. and Clayton, P. (2001) Marine mammal strandings: a collaborative study for the Irish Sea. Report for the Maritime Ireland/Wlaes INTERREG 1994–1999 (Report No. 8).Google Scholar
SCOS (Special Committee on Seals) Report (2007) Scientific advice on matters related to the management of seal populations. Sea Mammal Research Unit, School of Biology, University of St Andrews.Google Scholar
Silva, M.A. (1999) Diet of common dolphins, Delphinus delphinus, off the Portuguese continental coast. Journal of the Marine Biological Association of the United Kingdom 79, 531–540.CrossRefGoogle Scholar
Spitz, J., Mariotti, L., Ridoux, V., Caillot, E. and Elder, J.F. (in press) The diet of harbour seal Phoca vitulina at the southern limit of its European distribution (Normandy, France). The North Atlantic Marine Mammal Commission, special issue.CrossRefGoogle Scholar
Thompson, P.M., Pierce, G.J., Hislop, J.R.G., Miller, D. and Diack, J.S.W. (1991) Winter foraging by common seals (Phoca vitulina) in relation to food availability in the inner Moray Firth, N.E. Scotland. Journal of Animal Ecology 60, 283–294.CrossRefGoogle Scholar
Thompson, P.M. and Wheeler, H. (2008) Photo-ID-based estimates of reproductive patterns in female harbour seals. Marine Mammal Science 24, 138–146.CrossRefGoogle Scholar
Tollit, D.T., Steward, M.J., Thompson, P.M., Pierce, G.J., Santos, M.B. and Hughes, S. (1997) Species and size differences in the digestion of otoliths and beaks: implications for estimates of pinniped diet composition. Canadian Journal of Fisheries and Aquatic Science 54, 105–119.CrossRefGoogle Scholar
Walton, M.J., Henderson, R.J. and Pomeroy, P.P. (2000) Use of blubber fatty acid profiles to distinguish dietary differences between grey seals Halichoerus grypus from two UK breeding sites. Marine Ecology Progress Series 193, 201–208.CrossRefGoogle Scholar
Warner, P.J. (1983) An assessment of the breeding populations of common seals (Phoca vitulina vitulina L.) in the Republic of Ireland during 1979. Irish Naturalists' Journal 21, 24–26.Google Scholar
Watt, J., Pierce, G.J. and Boyle, P.R. (1997) Guide to the identification of North Sea fish using premaxillae and vertebrae. ICES Cooperative Research Report No. 220.Google Scholar
Wilson, S.C., Pierce, G.J., Higgins, C. and Armstrong, M.J. (2002) Diet of harbour seals of Dundrum Bay, north-east Ireland. Journal of the Marine Biological Association of the United Kingdom 82, 1009–1018.CrossRefGoogle Scholar
Zuur, A.F., Leno, E.N. and Smith, G.M. (2007) Analysing ecological data (statistics for biology and health). New York: Springer, 672 pp.CrossRefGoogle Scholar