Scientific investigations of the National Marine Mammal Laboratory, 1990

Abstract

Field research was carried out on Seal Island (60°59.5'S, 55°24.5'W), South Shetland Islands from 14 December 1989 to 27 February 1990. The main focus ofstudy was the ecology and population biology of Antarctic fur seals Arctocephalusgazella (Bengtson and others 1990a, b)and chinstrap Pygoscelis antarctica and macaroni Eudyptes chrysolophus penguins (Bengtson and others 1990a; Croll and others 1990). Analysis of stomach and fecal contents of live adult and sub-adult animals showed that krill were predominate in the diets of all three species, especially the penguins. Prey fed to penguin chicks by their parents contained 99% krill by weight. Thedietof fur seals varied from principally krill (62%), to fish (13%), to mixed krill and fish (25%). Traces of squid beaks were found in 15% of the fur seal stomach samples. Time-depth recorders and radio transm itters were attached to 14 fur seals, 10 macaroni penguins and 40 chinstrap penguins, to assess foraging behavior. Fur seals foraged at depths averaging 20—30 m, and the penguins 35–50 m. All three species swam to areas 11—100 km north of Seal Island to feed (water depths varied from 200 m to greater than 3000 m). These results are consistent with data collected in 1988 and 1989.