Concentrations of PCB (polychlorinated biphenyls, a class of industrial chemicals), DDE (the primary breakdown product of the pesticide DDT), and HCB (hexachlorobenzene, a fungicide) were determined in blubber samples from 45 harbor porpoises collected along the coasts of Washington, Oregon, and California. The primary purpose of this study was to test for regional patterns in the concentration of contaminants and their ratios in order to evaluate the feasibility of using contaminants to gain information about the degree of intermixing of harbor porpoises along the west coast of North America. Concentrations varied widely with averages of 14 ppm (mg/kg by we weight) PCBs, 31 ppm DDE, and 0.51 ppm HCB. Concentrations of contaminants were strongly associated with latitude (location), length of the animal, and sex. Distinct regional patterns were found in both the concentrations of DDE and the ratios of PCB to DDE and HCB to DDE. Contaminant ratios were far less variable than individual contaminant concentrations and were, therefore, more useful for examining regional patterns. Through discriminant analysis using a combination of pollutant rations, the state (California, Oregon, or Washington) in which harbor porpoises were collected could be correctly predicted for 86% of the samples. Pollutant ratios did not reveal specific boundaries for stocks but indicated that harbor porpoise movements may be restricted in some areas.
Citation:
Calambokidis, J., and J. Barlow. 1991. Chlorinated hydrocarbon concentrations and their use for describing population discreetness in harbor porpoises from Washington, Oregon, and California. In (J.E. Reynolds III and D.K. Odell (eds.). Marine mammal strandings in the United States: proceedings of the Second Marine Mammal Stranding Workshop; 3-5 December 1987, Miami, Florida. NOAA Technical Report NMFS 98:101-110.
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