ORGANOCHLORINE RESIDUES IN HARP SEALS, PHOCA-GROENLANDICA, FROM THE GULF OF ST-LAWRENCE AND HUDSON STRAIT - AN EVALUATION OF CONTAMINANT CONCENTRATIONS AND BURDENS

We evaluated organochlorine contaminant concentrations and burdens in blubber samples from 50 harp seals (Phoca groenlandica) obtained from the estuary and northern Gulf of St. Lawrence and Hudson Strait, Canad a, between December 1988 and December 1989. The concentration and burd en of PCBs increased significantly during the winter months for males occupying the St. Lawrence estuary. The potential for rapid accumulati on of contaminants in the estuary was also observed among females: nin e postpartum females (1 month after weaning) had higher organochlorine levels than prepartum females from the same location. The lowest obse rved contaminant concentrations and burdens were in seals from Hudson Strait in autumn. In winter specimens, males had DDT and PCB concentra tions about 4 and 2 times as great, respectively, as females of simila r age distribution and collection date. Congeners with IUPAC Nos. 138 and 153 accounted for more than 50% of total identifiable PCBs, which is consistent with their prevalence in other marine biota. The concent ration of PCBs has declined and the percent p,p'-DDE of total DDT has increased between 1982 and the present study. Unlike the beluga whale (Delphinapterus leucas), harp seals occupy the more polluted waters of the estuary only seasonally, and this may account for their lower res idue concentrations.