Investigation into Relatively High Walleye Mercury Concentrations in Tathlina Lake


PROJECT LEAD: Deborah MacLatchy (Laurier)
PROJECT TEAM MEMBERS: Andrea Lister (Laurier)

Heidi Swanson (University of Waterloo)

PROJECT LOCATION: Kakisa Lake, Tathlina Lake

Food fishes from Tathlina and Kakisa lakes in the Northwest Territories are of significant commercial and subsistence importance to the Ka’a’gee Tu First Nation (KTFN). Recent research from 2013-2015 (Low, Branfireun, Swanson) has shown that mercury levels in walleye differ significantly between the two lakes; walleye from Tathlina Lake have substantially higher mercury levels (that often exceed Health Canada guideline) than walleye from Kakisa Lake. In contrast, northern pike have similar mercury levels in the two lakes. These differences 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 propose to initiate a two year study on Tathlina and Kakisa lakes. We will build on our existing dataset by increasing fish sample sizes in both lakes, augmenting our sampling and understanding of mercury accumulation in lower trophic levels in

the food web (e.g., algae and plankton), sampling water and sediment in multiple seasons, and determining the amount of mercury in sediment that is available for uptake into the food web. Sampling will be done in collaboration with KTFN fishers and the environmental research coordinator, and continue to foster the two-way knowledge exchange that has been built during the last four years of collaborative research on these lakes.



The Environmental Coordinator (Melaine Simba) and the Chief of KTFN (Lloyd Chicot) has been consulted regarding our intent to continue our work with the community in generating data that addresses their concerns over the health of fish at Tathlina and Kakisa lakes.  Consultations of a more formal manner with the community will take place prior to the KTFN signing off on the project. Specifically, we will involve a minimum of the following people: Melaine Simba (Environmental Coordinator, KTFN), Lloyd Chicot (Chief, KTFN), and Fred Simba and Chris Chicot (fishers, KTFN).

Northern Capacity Building and Training

Members of the community that are hired to assist with the logistics of the field trips, collect biotic and abiotic samples, and assist on-site at the remote camp on Tathlina Lake will benefit from working directly with researchers from Wilfrid Laurier University and the University of Waterloo.  New training on field sampling techniques for the characterization of food webs at the lakes will be demonstrated, along with the opportunity for the community members to continue to sample fish according to the standardized sampling methods that have already been taught.  Some of our community partners have received their Aurora Collage certification through the five week environmental training course. As we have done in previous projects, Dehcho Youth will be engaged during the field season to learn about mercury and long-range transport pathways as well as the benefits and risks involved with eating country food. This work will continue to provide opportunities for community members and youth to participate in western science methods.


This project was explained at the annual AAROM meeting in March 2017, and via phone conversations this winter/spring. Swanson travelled to Kakisa in November 2016 to explain results of the previous phase of the research, and gather information on current community research interests (which this proposal was developed around). The involved First Nation Chief and Environmental Coordinator for KTFN will sign off on the NCP “Approval of Consultation” form during/after the AAROM meeting, and signed forms will be forwarded to the NCP Secretariat. Through existing relationships, the research team will work on a first-hand basis with the KTFN community during the study.