Digestive tracts of 61 ribbon seals (Phoca fasciata) collected in the seasonal pack ice of the Bering Sea during March to June 1976–1979 were examined. Very little fresh food was found in stomachs; however, hard parts of prey, particularly fish otoliths, were found in stomachs and (or) intestines of 28 seals. Based on counts of otoliths, the main prey were pollock in south-central and central Bering Sea, and arctic cod in northern Bering Sea. Weights and lengths of fishes consumed by seals were estimated from measurements of otoliths. On the basis of estimated whole weight of prey consumed, eelpout were a major food of these seals in south-central and central Bering Sea. Comparison of the species composition of fishes caught in trawls and eaten by seals suggests that seals in central and northern Bering Sea select for pollock and arctic cod, and against sculpins and capelin. In contrast, in south-central Bering Sea pollock was the most abundant fish in both seals and trawls. Seals were nonselective with regard to size of pollock consumed but appeared to select for large arctic cod. Our data suggest feeding conditions may be more favorable for ribbon seals in south-central Bering Sea than in more northern areas.
Diet and body condition of spectacled eiders wintering in pack ice of the Bering Sea