Fish Contaminant Assessment in the First Nation Communities of Sachigo Lake and Slate Falls

Communities of the Windigo First Nations Council in Sioux Lookout, Ontario were concerned  about the rise in levels of metal seen in fish during the past 20 years. Residents wanted to determine if fish required restrictions on consumption to protect their health. Sources of contamination included mining sites, acid rain, waste disposal sites, and airborne dispersal. The objective of the study was to assess metals in fish tissue within the waters surrounding the First Nation communities of Sachigo Lake and Slate Falls as a basis for consumption guidelines.

The project team collected fish samples (walleye and whitefish) from each member community of the Windigo First Nations Council and analyzed the samples for arsenic, chromium, cadmium, copper, manganese, nickel, lead, selenium, total mercury, iron, and zinc. They compared this data with data from other First Nation communities in the region.

The project team concluded that the elevated levels of chromium detected in the fish samples likely came from the sampling equipment (filet knife) rather than the fish itself. The presence of chromium, manganese and nickel suggested a potential source of metals from knife sharpening and fish processing.

The metal concentrations in fish at Bearskin Lake were generally low except for chromium and mercury in larger walleye. Due to the mercury levels in larger walleye, the team recommended children, pregnant women, and women of childbearing age avoid eating more than four meals per month of large walleye. Arsenic was also found to be a concern for all walleye sampled from Slate Falls and Lingman Lake. Therefore, the study authors recommended residents limit their consumption of walleye from these locations to one meal per week.