Investigation into relatively high Walleye mercury concentrations in Tathlina Lake and Kakisa Lake, Northwest Territories

Recent research from 2013-2015 (Low, Branfireun, Swanson) showed that mercury levels in Walleye differ significantly between two connected lakes; Walleye from Tathlina Lake have substantially higher mercury levels (that often exceed Health Canada guideline) than Walleye from Kakisa Lake. Both lakes are fished (Kakisa is fished commercially) by members of the Ka'a gee Tu First Nation, and Northern Pike have similar mercury levels in the two lakes. The differences in mercury between lakes and species cannot be fully explained by existing data on fish ecology, age, growth rate, or water and sediment chemistry. In response to community questions regarding high mercury levels in Tathlina Lake Walleye, we are studying biotic and abiotic components of both Tathlina and Kakisa lakes.