Cold Winter Could Lead to Fish Kills

Our extra-cold and snowy winter could cause an increase in dead fish and other aquatic animals this spring in inland lakes.

Michigan DNR Fisheries Division research manager Gary Whelan says winterkill is the most common type of fish kill. Thick ice with heavy snow cover decreases the amount of sunlight passing through to the water. That kills aquatic vegetation. As the vegetation decays, it takes dissolved oxygen out of the water, causing fish, turtles, frogs and other aquatic animals to die.

Such fishkill may not be noticed until a month after the ice has melted, as water turns over, and brings up the remains. Shallow lakes with excess vegetations and soft bottoms are most likely to be affected.

Fishkills involving 25 fish or more should be reported to the DNR.