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 species on
the Fraser and Columbia Rivers of northwestern North America. Carcasses of river otter (Lutra
canadensis) (N=24) and mink (Mustela vison) (N=34) were obtained from commercial trappers
during the winters of 1990-91 and 1991a??92. Pooled liver samples were analyzed for organochlorine
pesticides, polychlorinated biphenyls (PCBs), including non-ortho congeners, polychlorinated
dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs). Most samples contained detectable concentrations
of DDE, PCBs, although there was substantial variability in patterns and trends among
neighboring samples. Concentrations of DDE were in some mink and several otter samples from the
lower Columbia River elevated (to 4700 g/kg wet weight); excluding one mink sample from the
Wenatchee area, mean DDE levels generally decreased between 1978a??79 and 1990a??92. PCBs were
present in all samples. PCB concentrations in otter livers collected from the lower Columbia were
ten-fold lower than measured a decade previously; nevertheless, a sample taken near Portland had
a mean concentration of 1500 g/kg, within a range of concentrations associated with reproductive
effects in captive mink. Concentrations of 2,3,7,8-TCDD and TCDF were generally below detection
limits, except for one otter collected near a pulp mill at Castlegar, on the upper Columbia, with 11
ng TCDD/kg in liver. Elevated concentrations of higher chlorinated PCDD/Fs, probably 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.