| Summary: | The harbor seal population on Svalbard, the northernmost breeding site for this species, appears to have a truncatedage distribution with older animals being largely absent.PCBs and pesticides were measured in harbor seal males,females, milk and pups from Svalbard to explore whether contaminant exposure or accumulation is a possible causeof premature death for these animals.The levels and patterns of these contaminants were assessed. In addition,transfer of these compounds from females to their pups during lactation was assessed.Both PCB and pesticide levelswere low compared to more southern harbor seal populations.Animals from Svalbard contained 5–10 times lowercontaminant levels, compared to seals from the Norwegian mainland, and 30 times lower concentrations than thoseof harbor seals from the Gulf of St.Lawr ence in eastern Canada. Ringed seals from Svalbard have contaminant levelsthat are comparable to the harbor seals, probably because the diet, as well as the metabolic capacity, of the twospecies is similar at this location.The findings of this study indicate that the early mortality observed for harbor sealson Svalbard, is not likely to be due to contaminant exposure.Female harbor seals transfer a modified contaminantmixture to their pups compared to that found within their own tissues; compounds with higher log Kow, such as somepenta-chlorinated PCBs, were selectively transferred into milk.As a result, the contaminant pattern between malesand females differed, with penta-chlorinated PCBs more abundant in males than in females.In addition, pups receivea relatively high amount of the less lipophylic compounds and a low amount of the more lipophylic compounds.Thesimilar contaminant pattern in milk and pups suggested that they are probably unable to metabolize contaminants andconsequently, accumulate all ingested chemicals.
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