Fish Biomonitoring study

Members of the Michipicoten First Nation (MFN) in northern Ontario were concerned with the current state of fish due to increasing levels of contaminants such as methylmercury.  Many aquatic habitats within MFN’s traditional territory had not been sampled since the 1980s. This gap meant current information on chemical substances in fish tissue was largely absent and fish consumption risk assessments in this area were incomplete or out-of-date. The objectives of this project were to document historical concentrations of mercury in fish, document current concentrations of fish contaminants  (including mercury) in traditional MRN fisheries, and update local fish consumption recommendations in these fisheries.

The project team conducted an extensive literature review of historical studies and testing of fish in the area. The project team collected samples of fish tissue from northern pike and lake trout which they analyzed for PCB's, dioxins, furans, mercury, and arsenic. The fish were harvested from a range of habitats associated with various land uses in MFN territory including metal and aggregate mine areas and an established electricity transformer station. The fish across habitats of concern for this project were: White Lake and Dog Lake, Goudreau Lake, Borden River watershed, Herman-Otto Lakes, Michipicoten Bay, Lake Superior, Eagle River watershed, and Anjigami Lake.

The results of the analysis of fish tissue confirmed mercury continued to be the primary contaminant of concern in fish harvested in the MFN territory as tissue samples consistently exceeded guidelines. Elevated mercury concentrations were observed in large predatory fish species such as northern pike and lake trout. Collectively, the information from this 2021 sample analysis, the literature reviews, recent Ontario sample results, and other information all indicate that methylmercury is a wide-scale regional problem. These results highlight the need to update consumption recommendations for all consumers of wild fish with easy-to-follow guidance to reduce the risk of mercury exposure from the consumption of locally harvested fish. The team recommended further study on the impacts to wildlife that consume fish with elevated mercury levels.