MADISON, Wis. (WSAU) -- The long, cold winter means more than just more ice on lakes and rivers. Wisconsin Department of Natural Resources officials say the extended period of ice cover has led to less oxygen in the water because the sunlight cannot penetrate the ice and snow to reach the underwater plants.
Paul Cunningham is a Department of Natural Resources fisheries ecologist. He says, "Shallow lakes with large amounts of aquatic vegetation and mucky bottoms are prone to this problem. They have much lower oxygen capacity to begin with, and that oxygen is consumed as the plants decay, leaving little for fish and other aquatic life as the ice cover prevents oxygen from the atmosphere from reaching the water.”
The ice was over three feet thick in many areas this winter, so DNR officials say there is a good chance people will see a larger number of dead fish along the shorelines this spring. DNR rangers say this is a fairly normal process, but they encourage people to report any large numbers of dead fish in case there are other causes that need investigation.