Lands, Resources and Heritage

TKC Lands Steward Justin Jacobs and Fish and Wildlife Monitor Jonathan Burdek will continue to support contaminants monitoring in Braeburn Lake, Fox Lake and Lewes Marsh in 2026. Total mercury levels of Lake Trout in the Yukon were found to be generally low; however, the sample size was considered too small to make a lot of conclusions and more sampling is needed to confirm. CLICK HERE FOR MORE INFO

PRESS RELEASE: Lake Trout from Watson Lake have High Levels of DDT

The Northern Contaminants Program has been monitoring contaminants in Lake Trout from Kusawa Lake and Lake Laberge since the early 1990s. More recently we have added an additional lake each year to get an idea of what contaminants are in Lake Trout from other lakes. In 2024, in collaboration with Yukon Environment, we sampled Lake Trout from Watson Lake. We recently received the results of the tissue analysis and found very high levels of DDT in the muscle of these trout. DDT is a pesticide that was widely used in the past and is now banned in Canada. It remains in the environment and can accumulate in fish and other animals. DDT has been identified by international and Canadian health authorities as a contaminant of concern.

The Chief Medical Officer of Health, who is also a member of the local Yukon Contaminants Committee, has been briefed on these data and has advised that an exposure assessment be conducted and coupled with representative fish sampling to make recommendations about fish consumption from Watson Lake. The Yukon Contaminants Committee has also been briefed on these data.

While, as a scientist, it is not my role to provide health advice, it is my role to draw attention to levels of contamination that might be of concern and I can provide the math that I use to determine whether this was the case. The World Health Organization uses a Provisional Tolerable Daily Intake of 0.01 mg/kg body weight/day. For a 70 kg person, for the Watson Lake Lake Trout from 2024, this translates into a maximum recommended intake of 0.41 g/day, or 150 g/year. This is about one meal/year.

DDT is a known contaminant in Watson Lake, since heavy aerial spraying of DDT in the area in the 1950’s and 1960s. A study of the sediments in the lake in 2000 showed that Watson Lake had about 100 times as much DDT as other Yukon lakes. A study of the fish in Watson Lake in 1994 showed DDT concentrations in the muscle of Lake Trout that were three times higher than our findings, so it looks like the levels are decreasing over time.

Our current data is based on only five fish (according to our NCP protocol for ‘extra’ lakes) and these were big, old fish, which would be expected to have higher concentrations of these contaminants than smaller younger fish. We are currently trying to secure funding to analyze an additional 15 lake trout that were sampled in 2024 to get a better idea of the range of contamination in a larger range of fish sizes.

If you have any questions about these data, please contact:

Mary Gamberg,  Research Scientist

Whitehorse YT

867-334-3360           mary.gamberg@gmail.com