Protecting Coldwater Fish from Climate Change: Building Resilience in Deep Lakes using a Landscape Approach

By protecting the water quality in 176 “refuge” lakes, coldwater fish such as cisco are expected to persist in Minnesota, even after climate warming. Coldwater fish such as cisco, lake whitefish, and lake trout have a requirement for cold, well-oxygenated water and primarily live in deep lakes in Minnesota that have good water quality. This requirement makes them especially vulnerable to two of the greatest threats for Minnesota lakes – eutrophication and climate warming.
Fortunately, many deep lakes with good water quality maintain adequate oxygen conditions below the thermocline all summer long, even in warm summers. The Minnesota DNR Fisheries Research Unit, in conjunction with the University of Minnesota, have identified 176 “refuge” lakes in Minnesota that are deep and clear enough to sustain cisco,  even after climate warming. Maintaining the water quality in these lakes is critical for them to function as refuges to climate change. The Minnesota Department of Natural Resources is starting to protect the water quality in these important lakes. Partnering with other state agencies such as the Minnesota Pollution Control Agency and Board of Water and Soil Resources, local units of government, and lake associations will be a key strategy for protecting water quality. These strategies will primarily focus on keeping the forested lands forested in the watersheds of these lakes (most are located in the forested portion of Minnesota).