Mercury levels in tissues of otters from Ontario, Canada: Variation with age, sex and location.

G. Mierle* (Dorset Environmental Science Centre, Ontario Ministry of the Environment, Dorset, Ont. P0A 1E0, Canada), E. M. Addison, K. S. MacDonald, D. G. Joachim (Trent University Science Complex, Ontario Ministry of Natural Resources, P. O. Box 4840,Peterborough, Ont. K9J 8N8)

Concentrations of mercury in hair, brain and liver tissues of river otter (Lutra canadensis) from several townships in Ontario, Canada were determined. Levels of Hg in these tissues were highly intercorrelated, but differed from tissue to tissue. The highest concentration was in hair followed by liver and brain. The high correlation between Hg in hair and brain, as well as the ease and precision of Hg determinations on hair, demonstrate that Hg in hair holds considerable promise for monitoring the Hg in otters. Within the sampled otters Hg varied with respect to age. The Hg concentrations increased over the first 2 to 3 years of age, remained stabile over the next 2 to 3 years of age and then declined in the remaining age groups. Mean age of otters in townships with high Hg concentrations was about half the mean age of otters in low Hg townships. In areas where mercury levels are high, otters may have reduce survivorship due to Hg-induced stress on their health.