The summer diet of hooded (Cystophora cristata) and harp (Pagophilus groenlandicus) seals in the West Ice

摘要

The harp (Pagophilus groenlandicus) and hooded (Cystophora cristata) seals both inhabit the drift ice areas in the West Ice during certain times of the year, and the present study is part of the Institute of Marine Research’s management studies of these seals.Contents of gastrointestinal tracts from hooded and harp seals from June-July 2008 and 2010 and harp seal faeces samples were identified to the nearest possible taxon, and the prey importance was estimated both qualitatively and quantitatively. The diet composition of the seals differed much; polar cod dominated the hooded seal diet, whilst amphipods dominated the harp seal diet. The occurrence of polar cod, Themisto sp., krill and Gonatus fabricii in the diets of the two seal species coincides well with the distribution of these prey items, as well as the recorded dive depths of the seals. The inclusion of sculpins and snailfish in the diet of some of the hooded seals was likely because of temporal availability rather than changes in prey preference. Both seal species showed a rather narrow niche breadth. The total prey consumption during summer for the hooded seal population was estimated to 42,000 tonnes, and 300,000 tonnes for the harp seals.