Iowa Experiencing Winter Fish Kills

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The Iowa Department of Natural Resources has received numerous reports of dead fish in lakes and ponds across Iowa as the ice cover disappears for another year.

Winter fish kills have been reported at Swan Lake (Carroll), Badger Creek Lake (Madison), Clark Lake (Cerro Gordo), Kuhn Wildlife Pond (Cerro Gordo), Pilot Knob Pond (Winnebago), Alice Wyth Lake (Black Hawk), Middle Sabula and Green Island lakes (Jackson), Credit Island Lagoon (Scott), and a storm water retention pond in Guttenberg.

Fisheries staff are also watching lakes and ponds with low oxygen levels that are at risk of having a winter fish kill. Many north Iowa lakes and ponds are still under ice, so additional winter kills are likely.

Winter kills happen when a combination of ice and snow blocks sunlight from reaching aquatic plants, which in turn, stop producing oxygen. The longer the snow and ice cover lasts, the less oxygen is in the water.

Winter kills are visible shortly after ice out when fish that died during the winter float and are blown to shore. In certain lakes, like Rathbun, Black Hawk, Storm and Coralville, these dead fish are often a source of food for channel catfish that will go on a feeding spree. Many anglers see this as an early season fishing opportunity for trophy sized channel catfish.

“Channel catfish are attracted to food that gives off a strong odor and these dead fish put off an odor that will bring in catfish from across the lake. We tell anglers to fish on the windblown shore this time of year because the dead fish will be there, followed closely by the catfish. This can be some of the best fishing of the year,” Larscheid said.

source: Iowa Department of Natural Resources