A Comparison of Organochlorine Contaminant Levels, on a Lipid Basis, in Sea Lamprey Larvae from Mad River, Lake Huron Basin and Michipicoten River, Lake Superior Basin (1960-1976)

Organochlorine concentrations, on a lipid basis, were determined for formalin-preserved sea lamprey larvae, collected between 1960 and 1976 in the Mad River, Lake Huron basin, and compared with previously published data from Michipicoten River, Lake Superior basin. Although the ages of the lamprey specimens between the two lake basins were different, their lipid content, expressed as a percentage of dry body weight, was comparable. Despite the fact that the samples came from areas separated by about 550 km and with different land use (heavily forested area with mining activities but little agriculture for Lake Superior versus poultry farming, agricultural, urban and military uses for Lake Huron), no statistically significant differences were found for most organochlorine residue concentrations (Σaldrin, ΣCB, Σchlordane, ΣDDT, £ endosulfan and ΣPCB) between the two lake basins. The exception was ΣHCH, which was significantly lower in Lake Huron due to the absence of a high-level period observed in 1970 to 1975 in Lake Superior samples. Additionally, no differences were found between the relative concentrations of the various DDT metabolites between the two basins, but significantly higher relative concentrations of higher chlorinated PCBs (hexa to decachloro congeners) were found in Lake Huron samples. This study demonstrates the usefulness of formalin-preserved museum material to conduct retrospective contaminant analyses. However, given that certain amounts of contaminants were also found in the preservative solution, consideration of these levels is important to properly interpret the results.