DISTRIBUTION OF HEAVY-METALS IN MUSCLE, LIVER AND KIDNEY OF NORTHERN FUR-SEAL (CALLORHINUS-URSINUS) CAUGHT OFF SANRIKU, JAPAN AND FROM THE PRIBILOF ISLANDS, ALASKA

The concentrations of iron, manganese, zinc, copper, cadmium, and merc ury were determined ii? muscle, liver and kidney of 67 northern fur se als (Callorhinus ursinus) collected off Sanriku, Japan, and from the P ribilof islands, Alaska. Almost all the elements except cadmium were h ighest in liver. Cadmium levels in kidney were higher than those in li ver and muscle for all animals analyzed. Concentrations of mercury inc reased significantly with age in muscle, fiver and kidney, as did iron levels in muscle and liver and cadmium levels in muscle, while mangan ese concentrations decreased with age in muscle and kidney. The kidney also showed decreased copper concentration with age. Cadmium concentr ations of the northern fur seals in this study were higher than the ot her otariids, reflecting a predominantly squid diet. Concentrations of manganese and mercury were found to be higher in the fur seals caught off Sanriku than in animals from the Pribilof islands, while those of zinc and;cadmium were found to be lower. Variable concentrations of c admium might have been attributed to those in seawaters. Discriminant analysis of heavy metal concentrations was used to identify habitat. S ixty-three of 67 animals (94%) were correctly classified using this te chnique. Heavy-metal concentrations in tissues may provide a useful me thod to elucidate the primary feeding grounds of fur seals.