Predation on cephalopods by Antarctic fur seals, Arctocephalus gazella, at two localities of the Scotia Arc, Antarctica

Abstract

The cephalopod remains from 206 Antarctic fur seal (Arctocephalus gazella) scats collected at Mossman Peninsula, South Orkney Islands (n = 105) and at Stranger Point, South Shetland Islands (n = 101) contained 148 beaks (57 lower and 91 upper). The lower beaks were sorted and measured. Identification of 33 of the lower beaks that were collected at Mossman Peninsula revealed two squid species, Brachioteuthis ?picta (n = 26) and Psychroteuthisglacialis (n = 7), with lower rostral lengths (LRL) of 2.0–3.5 mm, and 1.0–2.5 mm, respectively. Identification of 15 of the lower beaks collected at Stranger Point revealed the same squid species, with the LRL of B. ?picta ranging from 3.0–3.4 mm (n = 9), and that of P. glacialis from 2.0 to 3.5 mm (n = 6). Estimated squid sizes and wet masses indicate that Antarctic fur seals feed on the small sub-adult squid which inhabit the surface layers. We have compared the squid diet estimated for the seals with that reported for its congeners in lower latitudes and other Antarctic seals, and conclude that cephalopods do not form an important food resource for Antarctic fur seals.