MERCURY LEVELS IN MICHIGAN RIVER OTTERS, LUTRA-CANADENSIS

Mercury (Hg) concentrations were examined in kidney and/or liver tissu es of 43 river otters collected from the upper and northern lower peni nsulas of Michigan from 1987-1989. In general, Hg concentrations in Mi chigan's otters were lower than reported for other localities in the U nited States but higher than concentrations reported in Michigan fish species. Concentrations were significantly higher in liver tissue rela tive to kidney tissue, averaging 2.18 mg Hg kg-1 dry weight +/- 0.25 ( S.E.) in the liver and 1.50 mg Hg kg-1 dry weight +/- 0.22 in the kidn ey. Hg concentrations in liver and kidney tissues were significantly c orrelated (r = 0.41, p < 0.05). When the data were pooled for all year s, Hg concentrations in liver tissue were statistically (94%) higher i n males than females. Additionally, Hg concentrations in kidney tissue were 18.5% higher in males than females, but this difference was not statistically significant. No statistically verifiable relationships w ere noted between Hg concentrations and age, weight, sampling region, or the interaction of these variables.