On Superior National Forest, where prescribed fire is being used to manage the threat of wildfire, Forest Service scientists found that light to moderate severity fires do not lead to increased mercury in fish.

After a historic blowdown event involving almost 500,000 acres on the Superior National Forest in northeast Minnesota, the possible implications of both wildfire and prescribed fire on the cycling of mercury and subsequent accumulation in fish became a significant concern for National Forest managers. The effect of fire on mercury accumulation in fish is particularly important to the Superior National Forest because much of the blowdown and subsequent fires occurred in the Boundary Waters Canoe Area Wilderness, the most visited Wilderness Area in the United States. Mercury is a pollutant that bioaccumulates in the food chain and can lead to deleterious health issues when ingested. Mercury is the main reason there are fish consumption advisories in every state in the United States and Canadian provinces. After a decade of research comparing fish from lakes in burned and unburned watersheds, Northern Research Station scientists’ main finding indicates that light to moderate severity fires do not lead to increased mercury in fish. This result is great news for the Superior National Forest managers as they continue to use prescribed fire to manage the threat of a large wildfire in blowdown area.