LANSING, MI (AP)-- As moderating temperatures melt snow and ice on Michigan lakes, officials are warning people to be prepared for the unpleasant sight of dead fish and other aquatic animals.
Fisheries habitat specialist Chris Freiburger of the Department of Natural Resources says it's common for many fish, turtles, frogs, toads and crayfish to die over the winter — especially when there's been heavy ice and snow cover.
So-called "winter kill" is particularly common in shallow lakes, streams and ponds. The culprit is lack of oxygen in the water.
Aquatic plants often stop producing oxygen as ice and snow reduce daylight. As the plants die, bacteria that decompose them use up what little oxygen is left.
That can cause fish and other animals to suffocate. As the ice recedes, their carcasses become visible.