Seasonal variation in the diet of Antarctic fur seals, Arctocephalus gazella, at 25 de Mayo/King George Island, South Shetland Islands, Antarctica

Abstract

Assessing the trophic ecology of fur seals is essential for defining their roles as a top predator in Antarctic marine ecosystems. To this end, we examined the diet of Antarctic fur seals, Arctocephalus gazella, in the South Shetlands. While previous studies have considered the diet of this species at this location in summer, to the best of our knowledge, this is the first study to report on the diet of this population in winter, thus adding essential information on the extent of seasonal variation. A total of 224 scats were collected in the winter 2004 (n = 118) and summer 2004/2005 (n = 106) on the coasts of Stranger Point, Isla 25 de Mayo/King George. For the total study period krill (Euphausia superba) was the main prey taxon, followed by fish, cephalopods and penguins. During winter Pleuragramma antarcticum was dominant, while myctophids were almost absent. Conversely, in summer Electrona antarctica and Gymnoscopelus nicholsi, followed by P. antarcticum, dominated the fish diet. It is concluded that fur seals centred their foraging activity on a krill community and fish associated with krill aggregations.