Diet of ringed seals (Phoca hispida) on the east and west sides of the North Water Polynya, northern Baffin Bay

In conjunction with the International North Water Polynya Study (NOW) in no rthern Baffin Bay, we examined the diets of ringed seals (Phoca hispida)(1) on the west (Grise Fiord, Nunavut) and east (Qaanaaq, Greenland) sides of the polynya, using conventional stomach content analysis, as well as infere nces from stable isotope ratios in seal muscle. Between May and July 1998, stomach and muscle tissue samples were collected from 99 ringed seals taken near Grise Fiord and 100 taken near Qaanaaq. The amphipod Themisto libellu la was the dominant prey type in the diet of immature ringed seals from Gri se Fiord, whereas arctic cod (Boreogadus saida) and polar cod (Arctogadus g lacialis) predominated in the diet of adults. Both immature and adult seals collected near Qaanaaq fed predominantly on arctic cod. Overall, seals col lected near Grise Fiord had significantly higher delta C-13 values than tho se collected near Qaanaaq (P < 0.001), but there was no statistical separat ion in delta N-15 values between the two samples (P = 0.06). Differences in diets of ringed seals from the east and west sides of the North Water Poly nya may be due to differences in prey distribution and/or differences in bi ological productivity and fish biomass within the polynya.