DNR Expert Talks About Spring Fish Kills

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The Michigan Department of Natural Resources is advising everyone fish kills are not an uncommon sight this time of year. DNR Fisheries Division program manager Gary Whelan tells WSJM News these spring fish kills typically occur in more shallow bodies of water.

“Under the ice, when you have deep ice cover and snow cover, the vegetation under the ice ultimately dies because it’s cut off from the light and doesn’t photosynthesize any further,” Whelan said. “So, once it dies, it starts to use oxygen and if indeed it uses enough oxygen or if you have a lot of vegetation under there that dies, it uses up all the oxygen and, ultimately, it kills fish. That’s what you’re seeing as the ice comes off this time of the year.”

Whelan says the DNR each spring will get reports from people about large numbers of dead fish floating in the water of lakes. He says in almost every case, it’s just a natural spring fish kill, and not the result of contamination or disease. He notes people can help reduce fish kills by regulating the nutrients they allow into bodies of water. Excessive plant growth in lakes can be caused by the runoff of fertilizer into the watershed.