Gray seal (Halichoerus grypus) diet composition in Nantucket Sound, US as inferred from fecal remains

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Considered extinct in U.S. waters prior to 1960, today there are more than 7,000 gray seals in the waters of Maine and Massachusetts alone. The diet and foraging habits of these seals in U.S. waters are not well studied. To help address this deficiency we inspected 114 gray seal scats for otoliths and other hard remains. We collected fecal material each season from 2004-2006 at two haulout sites in Nantucket Sound, Massachusetts. We identified otoliths and other diagnostic hard parts to the lowest practicable taxon, calculated the frequency of occurrence (FO) of prey taxa in scats, and the minimum number of prey individuals (MNI) consumed for each taxon. Sandlance (Ammodytes spp.) and red/white hake (Urophycis spp.) together accounted for 65% of prey individuals recovered. Skate (family Rajidae) was recovered most frequently, in 38% of samples. Cod (Gadus morhua) was recovered infrequently and comprised fewer than 2% of total individuals. Significantly more skate was recovered in fall than in other seasons.