Intraspecific differences in the diet of Antarctic fur seals at Nyrøysa, Bouvetøya

• Published in: Polar Biology
• Main Authors: Hofmeyr, G.J. Greg (Gordon John Gregory), Bester, Marthan Nieuwoudt, Kirkman, Steve P. (Stephen Patrick), Lydersen, Christian, Kovacs, Kit M., 1956-
• Format: Article in Journal/Newspaper
• Language: English
• Published: Springer 2010
• Subjects: Antarctic fur seal (Arctocephalus gazella); Southern fur seals > Antarctica > Feeding and feeds; Predation (Biology) > Antarctica > Sex differences; Competition (Biology) > Antarctica; Nutrition surveys > Antarctica > Sex differences; Pinnipedia > Antarctica > Feeding and feeds; Seals (Animals) > Food > Antarctica; Antarctic; Southern Ocean; The Antarctic; Bjørn; Bouvetøya; Nyrøysa; Antarc*; Antarctic Fur Seal; Antarctic Fur Seals; Antarctic Krill; Antarctica; Arctocephalus gazella; Euphausia superba; Norwegian Polar Institute; Polar Biology; Southern Fur Seals
• Online Access: http://hdl.handle.net/2263/16113; https://doi.org/10.1007/s00300-010-0805-0

Intraspecific differences in the diets of many species of pinnipeds are to be expected in view of the great differences in morphology, life history and foraging behaviour between the sexes of many species. We examined the diet of the Antarctic fur seal population at Bouvetøya, Southern Ocean to assess intersexual differences. This was made possible by the analysis of prey remains extracted from scats and regurgitations collected in areas used primarily by one or the other sex. The results indicate that both males and females feed primarily on Antarctic krill Euphausia superba with several species of fish and squid being taken, likely opportunistically given their prevalence. Significant differences were identified in the frequency of occurrence of otoliths in scats and the percentage numerical abundance of the major fish prey species in the diet. Adult males ate a smaller quantity of fish overall, but ate significantly more of the larger fish species. The greater diving capabilities of males and the fact that they are not limited in the extent of their foraging area by having to return regularly to feed dependant offspring may play a role in the differences found in the diets of males and females. Additionally, females might be more selective, favouring myctophids because they are richer in energy than krill. The absence of major differences in the diet between the sexes at this location is likely due to the high overall abundance of prey at Bouvetøya. This study was financed by the Norwegian Polar Institute (NPI) and the Norwegian Agency for Development Co-operation (NORAD). Further support was provided by the Mammal Research Institute of the University of Pretoria. We thank Bjørn Krafft, Ludvig Krag and Brian Flascas for their valuable assistance in the field. We are grateful to Bjørn Krafft, Iain Staniland and one anonymous reviewer for their comments and suggestions on the manuscript.