Feeding ecology of phocid seals and some walrus in the Alaskan and Canadian Arctic as determined by stomach contents and stable isotope analysis

Feeding habits of ringed (Phoca hispida), bearded (Erignathus barbatus), spotted (Phoca largha) and ribbon (Phoca fasciata) seals and walrus (Odobenus rosmarus) were studied using stomach contents and stable carbon and nitrogen isotopes. Bearded seals fed benthically, primarily crustaceans and mollusks. Both zooplankton and fish were significant prey for ringed seals, while fish was principal spotted seal prey. Few gastric contents were available from ribbon seals. delta N-15 was positively correlated with age in ribbon seals and delta(13)Cwas positively correlated with age in ringed and ribbon seals. delta(15)Nwas highest in spotted seals, in agreement with their fish-dominated diet. delta N-15 was not different between Alaskan-harvested ringed and bearded seals, while delta N-15 was lowest in ribbon seals and walrus. Carbon-13 was most enriched in bearded seals and walrus reflecting benthic ecosystem use. Canadian ringed seals were depleted in C-13 compared to Alaskan pinnipeds, likely because of Beaufort Sea versus Chukchi and Bering seas influence.