Chlorinated hydrocarbons in livers of american mink (Mustela vison) and river otter (Lutra canadensis) from the Columbia and Fraser River basins, 1990-1992

We investigated chlorinated hydrocarbon contaminants in aquatic mustelid sp ecies on the Fraser and Columbia Rivers of northwestern North America. Carc asses of river otter (Lutra canadensis) (N=24) and mink (Mustela vison) (N= 34) were obtained from commercial trappers during the winters of 1990-91 an d 1991-92. Pooled liver samples were analyzed for organochlorine pesticides , polychlorinated biphenyls (PCBs), including non-ortho congeners, polychlo rinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs). Most samples c ontained detectable concentrations of DDE, PCBs, although there was substan tial variability in patterns and trends among neighboring samples. Concentr ations of DDE were in some mink and several otter samples from the lower Co lumbia River elevated (to 4700 mu g/kg wet weight); excluding one mink samp le from the Wenatchee area, mean DDE levels generally decreased between 197 8-79 and 1990-92. PCBs were present in all samples. PCB concentrations in o tter livers collected from the lower Columbia were ten-fold lower than meas ured a decade previously; nevertheless, a sample taken near Portland had a mean concentration of 1500 mu g/kg, within a range of concentrations associ ated with reproductive effects in captive mink. Concentrations of 2,3,7,8-T CDD and TCDF were generally below detection limits, except for one otter co llected near a pulp mill at Castlegar, on the upper Columbia, with 11 ng TC DD/kg in liver. Elevated concentrations of higher chlorinated PCDD/Fs, prob ably resulting from use of chlorophenolic wood preservatives, were found in both species; one otter sample from the lower Columbia had 2200 ng OCDD/kg . International TCDD toxic equivalent levels in mink (31 ng/kg) and otter ( 93 ng/kg) from the lower Columbia River approached toxicity thresholds for effects on reproduction in ranch mink.