As snow and ice cover recede from Michigan lakes, officials say people should be prepared to see dead fish or other aquatic creatures in the water.
The Department of Natural Resources says winter conditions often cause die-offs of fish, turtles, frogs, toads and crayfish.
Martha Wolgamood of the Fisheries Division says "winter kill" is common, particularly in shallow lakes with excess vegetation and soft bottoms. It also happens in ponds, streams and canals.
She says the deaths don't affect the overall health of fish populations in the waterways.
Fish can become stressed in winter because of low energy reserves, with feeding at a minimum. They also can be affected by rapid changes in water temperatures.
Low oxygen levels are another factor, caused by decomposition of dead plants and animals.