The usual food source for individuals in the Atlantic Region is Antarctic krill ("Euphausia superba"); while in the Indian Ocean the diet is mostly based on fish and squid. The fish prey are principally myctophids, icefish, and Notothenids, although skates and rays are also consumed. Penguins are occasionally taken by Antarctic fur seal males. Seasonal differences in diet have been recorded across colonies, seasons and years. Studies have showed that female Antarctic fur seals can undertake wide-ranging foraging migrations during winter. Interannual differences appear to be related to differences in local oceanographic conditions.