Concentrations of PCB, DDE, HCB were examined in 51 blubber samples collected from 36 harbor porpoise collected along the coasts of Washington, Oregon, and California. The primary purpose of the study was to test for regional patterns in the concentration of contaminants and their ratios and to evaluate the feasibility of using contaminants to gain information about the degree of intermixing of harbor porpoise along the west coast of North America. Strong regional patterns were found in both the concentrations of DDE and the ratios of various contaminants. Contaminant ratios were far less variable then individual contaminant concentrations and were therefore more useful for examining regional patterns. The ratios of DDE/PCB and HCB/DDE showed the most dramatic differences by location with highly significant differences by state (ANOVA, p<0.001) and a strong correlation (p<0.001) between the ratio and latitude that the samples were collected. Within California samples from 3 subregions showed significant differences in contaminant ratios, though sample size was limited. The use of contaminant ratios to gain information on geographic interchange of harbor porpoise appears promising, especially in areas like California where the presence of pollutants in the marine environment varies widely by location.
Significant patterns were also found in contaminant concentrations by year collected, animals length, and blubber thickness. Replicate samples of the blubber taken from different locations on the bodies of two harbor porpoise showed minimal variation. Only samples from the dorsal peduncle area of the porpoise deviated from values obtained from other parts of the body.
Citation:
Calambokidis, J. 1986. Chlorinated hydrocarbons in harbor porpoise from Washington, Oregon, and California: Regional differences in pollutant ratios. Final report for Contract No. 40ABNF5 3875 from Southwest Fisheries Center, La Jolla, California. 29pp.