MINNEAPOLIS (WCCO) — Warmer temperatures this week will be accompanied with ice melt, which can bring an unsightly and smelly situation to some Minnesota lakes.

Dozens of dead, floating fish lined the edges of Lake Minnetonka this week, but they’re not cause for concern. Fish kill, or winter kill, is natural, even if Brian Nerbonne with the Minnesota Department of Natural Resources says it’s a little early in the year to hear reports of it.

Nerbonne, a regional fisheries manager, says when lakes are covered in ice and snow in winter, that blocks out the sun. Without light, underwater plants die and decompose.

“The oxygen level gets lower and lower in the water, and certain fish species especially are much more sensitive to that lower oxygen level and they’ll start to die,” Nerbonne said. “That happens under the ice, and people don’t even know it’s happening.”

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He says fish kill is more typically seen in shallow lakes because there’s less oxygen to begin with. It stands to reason that fish kill would be bad news for anglers, but Todd Stauffer, the owner of Set the Hook Guide Service, says it can actually help.

“If there’s too many fish, then that stunts the growth of them,” Stauffer said.

Nerbonne says winter kill is like a natural reset for some lakes, including Anderson Lake in Eden Prairie.

“[Anderson is] actually more waterfowl habitat than it is fish habitat, and so when we have fish that are living in that lake, they’ll actually eat the insects and things that those waterfowl would otherwise be eating, so it’s not really very good for those ducks,” he said.

The DNR asks people to make a report when they see large numbers of dead fish.

David Schuman