Diet of northwest Atlantic harp seals (Phoca groenlandica) in offshore areas

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The offshore diet of harp seals (Phoca groenlandica) in the northwest Atlantic was determined by reconstructing the contents of prey-containing stomachs (399 of 724) recovered during 1980–1995. The importance of prey species varied seasonally and geographically. Pups (< 6 months old) usually consumed invertebrates, capelin (Mallotus villosus), and sand lance (Ammodytes dubius). Subadults (6 months to 4 years old) consumed capelin and Arctic cod (Boreogadus saida) in the northern part of their range but sand lance and capelin on the Grand Banks. Adults consumed invertebrates such as shrimp (Pandalus sp.) and Natantia (amphipods) when they were collected on the northern Labrador Shelf, but ate capelin, Greenland halibut (Reinhardtius hippoglossoides), and Atlantic cod (Gadus morhua) on the southern Labrador Shelf. On the Grand Banks they consumed pleuronectids, sand lance, and capelin. Atlantic cod were rarely eaten by seals not caught by commercial trawlers. In contrast to the seals' nearshore diet, capelin were the principal prey on the Grand Banks and Labrador Shelf. Sand lance and Greenland halibut were also important. The contrast between near- and off-shore diets illustrates the importance of geographical variation in the contribution of a single prey species to the diet, especially in attempts to extrapolate consumption of specific prey.