Posted at: 05/16/2014 10:09 AM
Updated at: 05/16/2014 5:10 PM
Last winter's heavy snowfall is partly to blame for a fish kill that took out tens of thousands of walleye, bass, northern pike and other species on Grand Lake near Duluth.
Dan Wilfond is a Department of Natural Resources fisheries specialist. He says the kill was fairly severe, and he estimates 35,000 fish were affected. He said the 1600-acre lake is susceptible to winter kills, but that it hasn't happened there since the 1950s.
According to Anna Varian, the assistant area supervisor with the Duluth Area Fisheries Office, "the fish kill is caused by low dissolved oxygen levels in the water."
Varian said "during the winter with the ice cover and a lot of snow, not a lot of sunlight gets through to the lake...the aquatic vegetation in the lake isn't producing any oxygen. What's happening is they're dying off and that actually uses oxygen."
Because of the kill, Varian said the DNR is going to stock walleye in Grand Lake over the next three years - 750,000 walleye fry each year.
Varian said the DNR regularly monitors oxygen levels in the lake, as well as catch rates and the size and age of fish.
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