Abstract
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.
References
Ainley D, Blight L (2009) Ecological repercussions of historical fish extraction from the Southern Ocean. Fish Fish 10:13–38
Ainley D, Boekelheide R (eds) (1990) Seabirds of the Farallon Islands: ecology, structure and dynamics of an upwelling system community. Stanford University Press, Palo Alto
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 118:69–79
Atkinson A, Siegel V, Pakhomov E, Rothery P (2004) Long-term decline in krill stock and increase in salps within the Southern Ocean. Nature 432:100–103
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 14:293–309
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 14:83–87
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 7:43–52
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 64:1675–1691
Burger A, Piatt J (1990) Flexible time budgets in breeding common murres: buffers against variable prey abundance. Stud Avian Biol 14:71–83
Cairns D (1987) Seabirds as indicators of marine food supplies. Biol Oceanogr 5:261–271
Casaux R (2003) On the accuracy of the pellet analysis method to estimate the food intake in the Antarctic shag, Phalacrocorax bransfieldensis. Folia Zool 52:167–176
Casaux R (2013) Does prey availability influence the foraging effort and breeding success in the Antarctic Shag Phalacrocorax bransfieldensis? Chin Birds 4:240–247
Casaux R, Barrera-Oro E (1993) The diet of the Blue-eyed Shag, Phalacrocorax atriceps bransfieldensis at the West Antarctic Peninsula. Antarct Sci 5:335–338
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, Australia
Casaux R, Barrera-Oro E (2002) Effect of a shore-based sampling programme on Notothenia coriiceps populations. Antarct Sci 14:221–224
Casaux R, Barrera-Oro E (2006) Shags in Antarctica: their feeding behaviour and ecological role in the marine food web. Antarct Sci 18:3–14
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 299:267–274
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 14:32–36
Casaux R, Barrera-Oro E, Baroni A, Ramón A (2003) Ecology of inshore notothenioid fish from the Danco Coast, Antarctic Peninsula. Polar Biol 26:157–165
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 21:457–462
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 25:427–440
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 279–331
Ducklow H, Baker K, Martinson D (2007) Marine pelagic ecosystems: the West Antarctic Peninsula. Philos Trans R Soc Lond Ser B 362:67–94
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 146:50–58
Emslie S, Patterson W (2007) Abrupt recent shift in δ13C and δ15N values in Adélie penguin eggshell in Antarctica. Proc Natl Acad Sci USA 104:1666–11669
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 93:488–496
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 224:501–517
Kock K (1992) Antarctic fish and fisheries. Cambridge University Press, Cambridge
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 125–126:206–213
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 136:214–222
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 217–266
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 362:113–148
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 36:323–334
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 326–353
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. 120:125
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, Cambridge
Acknowledgments
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.
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Casaux, R., Barrera-Oro, E. Linking population trends of Antarctic shag (Phalacrocorax bransfieldensis) and fish at Nelson Island, South Shetland Islands (Antarctica). Polar Biol 39, 1491–1497 (2016). https://doi.org/10.1007/s00300-015-1850-5
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DOI: https://doi.org/10.1007/s00300-015-1850-5