Polar Biology

, Volume 39, Issue 8, pp 1491–1497 | Cite as

Linking population trends of Antarctic shag (Phalacrocorax bransfieldensis) and fish at Nelson Island, South Shetland Islands (Antarctica)

  • Ricardo CasauxEmail author
  • Esteban Barrera-Oro
Short Note


This study aims to provide consistent information to explain the steady declining trend in the number of breeding pairs of Antarctic shag Phalacrocorax bransfieldensis in two colonies on Nelson Island, South Shetland Islands, southern Atlantic sector of Antarctica, which was observed during the 1990s up to the mid 2000s over an overall monitoring period of over two decades. It addresses correspondence between long-term population trends of inshore demersal fish and inshore-feeding Antarctic shags of this area, where an intensive commercial fishery for shag prey once operated. The analysis also includes comparable information on diet (by examination of regurgitated pellets), foraging patterns, and breeding output of shags from the Danco Coast, western Antarctic Peninsula, an area where no commercial finfish fishery has ever existed. Integral study of these parameters there showed that, in Antarctic shags, low breeding success and high foraging effort might imply low recruitment and high adult mortality, respectively, with both factors adversely affecting the population trends of this bird. In line with these premises, the declining trend observed in shag colonies on the South Shetland Islands appears to have been influenced by the concomitant decrease in abundance of two of their main prey, the nototheniids Notothenia rossii and Gobionotothen gibberifrons, due to intensive industrial fishing in the area in the late 1970s. In comparison, no such pattern occurred for the Danco Coast colonies.


Antarctic shag Inshore fish Notothenioids Population trends South Shetland Islands 



We thank all of our colleagues who helped in the field activities, as well as three anonymous reviewers whose valuable advice helped to improve the manuscript. This is a contribution to the Laboratorio de Investigaciones en Ecología y Sistemática Animal, CIEMEP.


  1. Ainley D, Blight L (2009) Ecological repercussions of historical fish extraction from the Southern Ocean. Fish Fish 10:13–38CrossRefGoogle Scholar
  2. Ainley D, Boekelheide R (eds) (1990) Seabirds of the Farallon Islands: ecology, structure and dynamics of an upwelling system community. Stanford University Press, Palo AltoGoogle Scholar
  3. Ainley D, Sydeman W, Norton J (1995) Upper-trophic level predators indicate interannual negative and positive anomalies in the California Current food web. Mar Ecol Prog Ser 118:69–79CrossRefGoogle Scholar
  4. Atkinson A, Siegel V, Pakhomov E, Rothery P (2004) Long-term decline in krill stock and increase in salps within the Southern Ocean. Nature 432:100–103CrossRefPubMedGoogle Scholar
  5. Barrera-Oro E (2002) The role of fish in the Antarctic marine food web: differences between inshore and offshore waters in the southern Scotia Arc and west Antarctic Peninsula. Antarct Sci 14:293–309CrossRefGoogle Scholar
  6. Barrera-Oro E, Marschoff E (2007) Information on the status of fjord Notothenia rossii, Gobionotothen gibberifrons and Notothenia coriiceps in the lower South Shetland Islands, derived from the 2000–2006 monitoring program at Potter Cove. CCAMLR Sci 14:83–87Google Scholar
  7. Barrera-Oro E, Marschoff E, Casaux R (2000) Trends in relative abundance of fjord Notothenia rossii, Gobionotothen gibberifrons and Notothenia coriiceps at South Shetland Islands, after commercial fishing in the area. CCAMLR Sci 7:43–52Google Scholar
  8. Barrett R, Camphuysen C, Anker-Nilssen T, Chardine J, Furness R, Garthe S, Hüppop, Leopold M, Montevecchi W, Veit R (2007) Diet studies of seabirds: a review and recommendations. ICES J Mar Sci 64:1675–1691CrossRefGoogle Scholar
  9. Burger A, Piatt J (1990) Flexible time budgets in breeding common murres: buffers against variable prey abundance. Stud Avian Biol 14:71–83Google Scholar
  10. Cairns D (1987) Seabirds as indicators of marine food supplies. Biol Oceanogr 5:261–271Google Scholar
  11. Casaux R (2003) On the accuracy of the pellet analysis method to estimate the food intake in the Antarctic shag, Phalacrocorax bransfieldensis. Folia Zool 52:167–176Google Scholar
  12. Casaux R (2013) Does prey availability influence the foraging effort and breeding success in the Antarctic Shag Phalacrocorax bransfieldensis? Chin Birds 4:240–247CrossRefGoogle Scholar
  13. Casaux R, Barrera-Oro E (1993) The diet of the Blue-eyed Shag, Phalacrocorax atriceps bransfieldensis at the West Antarctic Peninsula. Antarct Sci 5:335–338CrossRefGoogle Scholar
  14. Casaux R, Barrera-Oro E (1996) Fish in the diet of the Blue-eyed Shag Phalacrocorax atriceps at the South Shetland Islands: six years of monitoring studies. SC-CAMLR-WG-EMM-96/31, CCAMLR, Hobart, AustraliaGoogle Scholar
  15. Casaux R, Barrera-Oro E (2002) Effect of a shore-based sampling programme on Notothenia coriiceps populations. Antarct Sci 14:221–224Google Scholar
  16. Casaux R, Barrera-Oro E (2006) Shags in Antarctica: their feeding behaviour and ecological role in the marine food web. Antarct Sci 18:3–14CrossRefGoogle Scholar
  17. Casaux R, Barrera-Oro E, Coria N, Carlini A (1998) Fish as prey of birds and mammals at the South Shetland Islands. In: Wiencke C, Ferreyra G, Arntz W, Rinaldi C (eds) The Potter Cove coastal ecosystem, Antarctica. Ber Polarforsch 299:267–274Google Scholar
  18. Casaux R, Baroni A, Barrera-Oro E (2002) Fish in the diet of the Antarctic shag Phalacrocorax bransfieldensis breeding at four colonies in the Danco Coast, Antarctic Peninsula. Antarct Sci 14:32–36Google Scholar
  19. Casaux R, Barrera-Oro E, Baroni A, Ramón A (2003) Ecology of inshore notothenioid fish from the Danco Coast, Antarctic Peninsula. Polar Biol 26:157–165CrossRefGoogle Scholar
  20. Casaux R, Bertolin M, Tartara M, Alarcón P, Porro G (2010) The unexpected diet of breeding Imperial Shags (Phalacrocorax atriceps) at the Nahuel Huapi Lake, Patagonia: implications on population trends? Ornitol Neotrop 21:457–462Google Scholar
  21. Crawford R, Cooper J, Dyer B, Wolfaardt A, Tshingana D, Spencer K, Petersen S, Nel J, Keith D, Holness C, Hanise B, Greyling M, du Toit M (2003) Population, breeding, diet and conservation of Crozet shag Phalacrocorax [atriceps] melanogenis at Marion Island, 1994/95 to 2002/03. Afr J Mar Sci 25:427–440CrossRefGoogle Scholar
  22. DeWitt H, Heemstra P, Gon O (1990) Nototheniidae. In: Gon O, Heemstra P (eds) Fishes of the Southern Ocean. JLB Smith Institute of Ichthyology, Grahamstown, pp 279–331Google Scholar
  23. Ducklow H, Baker K, Martinson D (2007) Marine pelagic ecosystems: the West Antarctic Peninsula. Philos Trans R Soc Lond Ser B 362:67–94CrossRefGoogle Scholar
  24. Elliott M, Bradley R, Robinette D, Jahncke J (2015) Changes in forage fish community indicated by the diet of the Brandt’s cormorant (Phalacrocorax penicillatus) in the central California current. J Mar Syst 146:50–58CrossRefGoogle Scholar
  25. Emslie S, Patterson W (2007) Abrupt recent shift in δ13C and δ15N values in Adélie penguin eggshell in Antarctica. Proc Natl Acad Sci USA 104:1666–11669CrossRefGoogle Scholar
  26. Fritz H, Durant D, Guillemain M (2001) Shape and sources of variations of the functional response of wildfowl: an experiment with mallards, Anas platyrhynchos. Oikos 93:488–496CrossRefGoogle Scholar
  27. Hislop J, Harris M, Smith J (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
  28. Kock K (1992) Antarctic fish and fisheries. Cambridge University Press, CambridgeGoogle Scholar
  29. Marschoff E, Barrera-Oro E, Alescio N, Ainley D (2012) Slow recovery of previously depleted demersal fish at the South Shetland Islands, 1983–2010. Fish Res 125–126:206–213CrossRefGoogle Scholar
  30. Monaghan P, Walton P, Wanless S, Uttley J, Burns M (1994) Effects of prey abundance on the foraging behaviour, diving efficiency and time allocation of breeding Guillemots Uria aalge. Ibis 136:214–222CrossRefGoogle Scholar
  31. Montevecchi W (1993) Birds as indicators of change in marine prey stocks. In: Furness R, Greenwood J (eds) Birds as monitors of environmental change. Chapman and Hall, London, pp 217–266CrossRefGoogle Scholar
  32. Murphy E, Watkins J, Trathan P (2007) Spatial and temporal operation of the Scotia Sea ecosystem: a review of large-scale links in a krill centered food web. Philos Trans R Soc Lond B Biol Sci 362:113–148CrossRefPubMedGoogle Scholar
  33. Naveen R, Forrest S, Dagit R, Blight L, Trivelpiece W, Trivelpiece S (2000) Censuses of penguin, blue-eyed shag, and southern giant petrel populations in the Antarctic Peninsula region, 1994–2000. Polar Rec 36:323–334CrossRefGoogle Scholar
  34. Orta J (1992) Family Phalacrocoracidae (Cormorants). In: del Hoyo J, Elliot A, Sargatal J (eds) Handbook of the birds of the world, vol 1. Lynx Editions, Barcelona, pp 326–353Google Scholar
  35. Suarez J (1927) Rapport au Conseil de la Société des Nations. Exploitation des Richesses de la Mer. Publications de la Société des Nations V. Questions Juridiques. V.1. 120:125Google Scholar
  36. Woehler E, Cooper J, Croxall J, Fraser W, Kooyman G, Miller G, Nel D, Patterson D, Petter H, Ribic C, Salwicka K, Trivelpiece W, Weimerskirch H (2001) A statistical assessment of the status and trends of Antarctic and Subantarctic seabirds. SCAR, CambridgeGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2015

Authors and Affiliations

  1. 1.CIEMEP (CONICET-UNPSJB)EsquelArgentina
  2. 2.Instituto Antártico ArgentinoBuenos AiresArgentina
  3. 3.Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)Buenos AiresArgentina
  4. 4.Museo Argentino de Ciencias Naturales Bernardino RivadaviaBuenos AiresArgentina

Personalised recommendations