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Marine Biology

, Volume 149, Issue 4, pp 979–990 | Cite as

Feeding ecology of sympatric European shags Phalacrocorax aristotelis and great cormorants P. carbo in Iceland

  • Kristjan LilliendahlEmail author
  • Jon Solmundsson
Research Article

Abstract

The feeding ecology of the European shag (Phalacrocorax aristotelis) and the great cormorant (P. carbo) in Iceland was studied. These bird species may affect their marine environment, for instance, by predating on several commercially important fish species in coastal waters. The shag and cormorant diets were studied throughout the year in the period 1996–2000 by analysing the content of about 300 stomachs from each species. The shag relies heavily on sandeel (Ammodytes marinus) in the breeding season, whereas bull-rout (Myoxocephalus scorpius) and gadoids (Gadidae) become increasingly important in autumn and winter. The main food of the cormorant in all areas and seasons is the bull-rout. Depending on location and season, secondary food consists mainly of butterfish (Pholis gunnellus), gadoids and flatfishes (Pleuronectiformes). Similarity in diets of these two co-existing bird species was least in the breeding season when overlap in the birds’ distribution was greatest. The results suggest that predation by shags and cormorants could sometimes affect the stocks of the commercially important saithe (Pollachius virens) and plaice (Pleuronectes platessa) in Iceland.

Keywords

Breeding Season Bird Species Stomach Content Prey Species Breeding Period 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Notes

Acknowledgements

Thanks are extended to Prof. A. Gardarsson for access to unpublished data and reading of the manuscript, and G.A. Gudmundsson for comments on the manuscript and help with figures. A. Galan participated in data collection, and R. Olafsdottir, S. Gudmundsdottir, G. Haraldsdottir and S. Egilsdottir analysed stomach contents. L. Taylor commented on the manuscript, T.S. Gestsdottir assisted with data management, V. Bogason identified otoliths and E. Hjörleifsson provided information on fishery statistics. Thanks are also extended to the many hunters and fishermen, too numerous to mention, for collecting birds and two anonymous referees for improving the manuscript.

References

  1. Anon (2005) State of Marine Stocks in Icelandic Waters 2004/2005. Prospects for the Quota Year 2005/2006. Hafrannsóknastofnun, Fjölrit 121, 182 pp (In Icelandic with an English summary, mimeo)Google Scholar
  2. Barrett RT (1991) Shags (Phalacrocorax aristotelis L.) as potential samplers of juvenile saithe (Pollachius virens (L.)) stocks in northern Norway. Sarsia 76:153–156Google Scholar
  3. Barrett RT, Furness RW (1990) The prey and diving depths of seabirds on Hornøy, North Norway after a decrease in the Barents Sea capelin stocks. Ornis Scand 21:179–186Google Scholar
  4. Barrett RT, Strann K-B, Vader W (1986) Notes on the eggs and chicks of North Norwegian shags Phalacrocorax aristotelis. Seabird 9:3–10Google Scholar
  5. Barrett RT, Røv N, Loen J, Montevecchi WA (1990) Diets of shags Phalacrocorax aristotelis and cormorants P. carbo in Norway and possible implications for gadoid stock recruitment. Mar Ecol Prog Ser 66:205–218Google Scholar
  6. Bearhop S, Thompson DR, Waldron S, Russel IC, Alexander G, Furness RW (1999) Stable isotopes indicate the extent of freshwater feeding by cormorants Phalacrocorax carbo shot at inland fisheries in England. J Appl Ecol 36:75–84CrossRefGoogle Scholar
  7. Birt-Friesen VL, Montevecchi WA, Cairns DK, Macko SA (1989) Activity-specific metabolic rates of free-living northern gannets and other seabirds. Ecology 70:357–367CrossRefGoogle Scholar
  8. Bogason V (1997) The diet of the harbour seal (Phoca vitulina) in Iceland. Hafrannsóknastofnun Fjölrit 57:319–330 (In Icelandic, mimeo)Google Scholar
  9. Brugger KE (1993) Digestibility of three fish species by double-crested cormorants. Condor 95:25–32Google Scholar
  10. Caddy JF (1991) Death rates and time intervals: is there an alternative to the constant natural mortality axiom? Rev Fish Biol Fish 1:109–138CrossRefGoogle Scholar
  11. Camphuysen CJ, Calvo B, Durinck J, Ensor K, Follestad A, Furness RW, Garthe S, Leaper G, Skov H, Tasker ML, Winter CJN (1995) Consumption of discards by seabirds in the North Sea. In: Final report EC DG XIV research contract BIOECO/93/10. NIOZ Rapport 1995–5, Netherlands Institute for Sea Research, Texel, 202 + LVI ppGoogle Scholar
  12. Carss DN, Ekins GR (2002) Further European integration: mixed sub-species colonies of great cormorants Phalacrocorax carbo in Britain - colony establishment, diet, and implications for fisheries management. Ardea 90:23–41Google Scholar
  13. Cowx IG (ed) (2003) Interactions between fish and birds: implications for management. Fishing News Books. Blackwell, OxfordGoogle Scholar
  14. Cramp S, Simmons KEL (eds) (1977) The birds of the Western Palearctic, Vol 1. Oxford University Press, OxfordGoogle Scholar
  15. Debout G, Røv N, Sellers RM (1995) Status and population development of cormorants Phalacrocorax carbo carbo breeding on the Atlantic coast of Europe. Ardea 83:47–59Google Scholar
  16. Duffy DC, Laurenson LJB (1983) Pellets of cape cormorants as indicators of diet. Condor 85:305–307Google Scholar
  17. Fiske E, Røv N (1997) Survival rates of great cormorant (Phalacrocorax carbo carbo) from ring-recovery data. Suppl Ric Biol Selvaggina 26:159–162Google Scholar
  18. Furness RW (2002) Management implication of interactions between fisheries and sandeel-dependent seabirds and seals in the North Sea. ICES J Mar Sci 59:261–269CrossRefGoogle Scholar
  19. Furness RW, Tasker ML (2000) Seabird–fishery interactions: quantifying the sensitivity of seabirds to reductions in sandeel abundance, and identification of key areas for sensitive seabirds in the North Sea. Mar Ecol Prog Ser 202:253–264Google Scholar
  20. Gardarsson A (1979) A census of breeding Cormorants (Phalacrocorax carbo) and Shags (Phalacrocorax aristotelis) in Iceland in 1975. Natturufraedingurinn 49:126–154 (In Icelandic with an English summary)Google Scholar
  21. Gardarsson A (1996) Numbers of breeding Cormorants Phalacrocorax carbo in Iceland in 1975–1994. Bliki 17:35–42 (In Icelandic with an English summary)Google Scholar
  22. Gardarsson A, Thorarinsson TL (2003) Distribution and numbers of harlequin ducks wintering in Iceland. Bliki 23:5–20 (In Icelandic with an English summary)Google Scholar
  23. Grémillet D, Schmid D, Culik B (1995) Energy requirements of breeding great cormorants Phalacrocorax carbo sinensis. Mar Ecol Prog Ser 121:1–9Google Scholar
  24. Grémillet D, Argentin G, Schulte B, Culik BM (1998) Flexible foraging techniques in breeding cormorants Phalacrocorax carbo and shags Phalacrocorax aristotelis: benthic or pelagic feeding? Ibis 140:113–119Google Scholar
  25. Grémillet D, Wilson RP, Wanless S, Peters G (1999) A tropical bird in the Arctic (the cormorant paradox). Mar Ecol Prog Ser 188:305–309Google Scholar
  26. Grémillet D, Wright G, Lauder A, Carss DN, Wanless S (2003) Modelling the daily food requirements of wintering great cormorants: a bioenergetics tool for wildlife management. J Appl Ecol 40:266–277Google Scholar
  27. Härkönen T (1986) Guide to the otoliths of the bony fishes of the Northeast Atlantic. Danibu ApS, Hellerup, DenmarkGoogle Scholar
  28. Harris MP, Wanless S (1991) The importance of the lesser sandeel Ammodytes marinus in the diet of the shag Phalacrocorax aristotelis. Ornis Scand 22:375–382Google Scholar
  29. Harris MP, Wanless S (1993) The diet of shags Phalacrocorax aristotelis during the chick-rearing period assessed by three methods. Bird Study 40:135–139CrossRefGoogle Scholar
  30. Hatch JJ, Brown KM, Hogan GG, Morris RD (2000) Great Cormorant (Phalacrocorax carbo). In: Pool A, Gill F (eds) The birds of North America, vol 553. The Birds of North America, Inc., PhiladelphiaGoogle Scholar
  31. Hauksson E (1997) The diet of the grey seal. Hafrannsóknastofnun, Fjölrit 57:331–342 (In Icelandic, mimeo)Google Scholar
  32. Hislop JRG, Harris MP, Smith JGM (1991) Variation in the calorific value and total energy content of the lesser sandeel (Ammodytes marinus) and other fish preyed on by seabirds. J Zool Lond 224:501–517CrossRefGoogle Scholar
  33. Horn HS (1966) Measurement of “overlap” in comparative ecological studies. Am Nat 100:419–424CrossRefGoogle Scholar
  34. Jobling M, Breiby A (1986) The use and abuse of fish otoliths in studies of feeding habits of marine piscivores. Sarsia 71:265–274Google Scholar
  35. Johnsgard PA (1993) Cormorants, darters, and pelicans of the world. Smithson Inst Press, Washington, DCGoogle Scholar
  36. Johnstone IG, Harris MP, Wanless S, Graves JA (1990) The usefulness of pellets for assessing the diet of adult Shags Phalacrocorax aristotelis. Bird Study 37:5–11CrossRefGoogle Scholar
  37. Jonsson G (1992) Icelandic fishes, 2nd edn. Fjolvi, Reykjavik (In Icelandic)Google Scholar
  38. Kirby JS, Holmes JS, Sellers RM (1996) Cormorants (Phalacrocorax carbo) as fish predators: an appraisal of their conservation and management in Great Britain. Biol Cons 75:191–199CrossRefGoogle Scholar
  39. Lack D (1945) The ecology of closely related species with special reference to Cormorant (Phalacrocorax carbo) and Shag (P. aristotelis). J Anim Ecol 14:12–16CrossRefGoogle Scholar
  40. Leopold MF, van Damme CJG, van der Veer HW (1998) Diet of cormorants and the impact of cormorant predation on juvenile flatfish in the Dutch Wadden Sea. J Sea Res 40:93–107CrossRefGoogle Scholar
  41. Lilliendahl K, Solmundsson J (1997) An estimate of summer food consumption of six seabird species in Iceland. ICES J Mar Sci 54:624–630CrossRefGoogle Scholar
  42. Lorentsen S-H, Grémillet D, Nymoen GH (2004) Annual variation in diet of breeding great cormorants: does it reflect varying recruitment of gadoids? Waterbirds 27:161–169Google Scholar
  43. Macer CT (1966) Sandeels (Ammodytidae) in the southwestern North Sea; their biology and fishery. MAFF Fish Invest 2(24):1–51Google Scholar
  44. Madsen FJ, Spärck R (1950) On the feeding habits of the southern cormorant (Phalacrocorax carbo sinensis Shaw) in Denmark. Dan Rev Game Biol 1:45–75Google Scholar
  45. Mills D (1969a) The food of the shag in Loch Ewe, Ross-shire. Scott Birds 5:264–268Google Scholar
  46. Mills D (1969b) The food of the cormorant at two breeding colonies on the east coast of Scotland. Scott Birds 5:268–276Google Scholar
  47. Morisita M (1959) Measuring of interspecific association and similarity between communities. Mem Fac Sci Kyushu Univ E (Biol) 3:65–80Google Scholar
  48. Okill JD, Fowler JA, Ellis PM, Petrie GW (1992) The diet of cormorant Phalacrocorax carbo chicks in Shetland in 1989. Seabird 14:21–26Google Scholar
  49. Pearson TH (1968) The feeding biology of sea-bird species breeding on the Farne Islands, Northumberland. J Anim Ecol 37:521–552CrossRefGoogle Scholar
  50. Pennington M, Osborn K, Harvey P, Riddington R, Okill D, Ellis P, Heubeck M (2004) The birds of Shetland. Christopher Helm, LondonGoogle Scholar
  51. Petersen A (1982) Seabirds. Rit Landverndar 8:15–60 (In Icelandic)Google Scholar
  52. Potts GR, Coulson JC, Deans IR (1980) Population dynamics and breeding success of the shag, Phalacrocorax aristotelis, on the Farne Islands, Northumberland. J Anim Ecol 49:465–484CrossRefGoogle Scholar
  53. Rae BB (1969) The Food of Cormorants and Shags in Scottish Estuaries and Coastal Waters. Dep Agric Fish Scotland Mar Res No 1Google Scholar
  54. Rindorf A, Wanless S, Harris MP (2000) Effects of changes in sandeel availability on the reproductive output of seabirds. Mar Ecol Prog Ser 202:241–252Google Scholar
  55. Wanless S, Harris MP (1997) The handbook of the birds of Europe, the Middle East, and North Africa Phalacrocorax aristotelis Shag. BWP Update 1:3–13Google Scholar
  56. Wilson RP (1984) An improved stomach pump for penguins and other seabirds. J Field Ornithol 55:109–112Google Scholar

Copyright information

© Springer-Verlag 2006

Authors and Affiliations

  1. 1.Marine Research InstituteReykjavikIceland

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