Spatial Variation in Mercury Concentrations in Wild Mink and River Otter Carcasses from the James Bay Territory, Québec, Canada

Abstract

Mercury concentrations were analyzed in different organs/tissues of wild minks (Mustela vison) and river otters (Lutra canadensis) trapped during two seasons in the James Bay territory (49°N to 55°N, Québec, Canada). In 1993–94, mean total Hg concentration (μg/g, wet weight) in 39 wild mink and 12 river otter carcasses was greatest in fur/hair samples (30.1 and 20.7 μg/g, respectively) and least in brain samples (0.96 and 0.8 μg/g, respectively) with liver, kidney, and muscle samples showing intermediate values. Pooling data from the 1993–94 and 1994–95 trapping seasons revealed mean (SD) liver total Hg concentrations of 3.71 μg/g (3.91) in 316 wild mink carcasses and 4.05 μg/g (3.41) in 153 river otter carcasses. Log liver total Hg concentration increased with age in wild mink but not in river otter. Log liver total Hg concentration in each species was greatest in areas with moraine deposits and least in areas with rich clay deposits, but the effect of soil deposits could be confounded by uneven deposition of anthropogenic Hg. Controlling for type of soil deposits, log liver total Hg concentration decreased with increasing distance from local industrial centers in each species but varied little with changes in distance from hydroelectric reservoirs. In a subsample of carcasses from the moraine sector, log liver total Hg concentration was higher in wild mink than in river otter. Spatial variation in log liver total Hg concentration in relation to soil deposit type and proximity to industrial centers suggests that the two wild furbearer species could be useful indicators of environmental contamination.