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Spawning stress causes panfish kills in Iowa lakes

  • 6/11/2019 3:32:00 PM
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Iowa Department of Natural Resources (DNR) fisheries biologists are starting to receive phone calls about dead bluegill and crappies in lakes.

“Several dozen dead panfish were reported at Lake Iowa Park in Iowa County early last week,” said Paul Sleeper, fisheries management biologist.

These natural fish kills are a common occurrence at a number of lakes each spring during spawning season. The spawning season is very stressful.

“We see more spawning stress fish kills when we have a cool spring and then everything warms up quickly, like it did this year,” explained Sleeper.  “Everything comes in to spawn at once and any infection can spread quickly through the population.”

Spawning season is not the only time natural fish kills occur, it also happens during ice out and the heat of July-August.  Natural fish kills periodically occur when populations reach certain levels and it usually only affects the weaker fish of one species. 

If you see several species or sizes of dead fish or a pollutant present, call the DNR’s 24-hour spill line at 515-725-8694 as soon as possible. Quick reporting can help DNR staff identify the cause of a fish kill and potentially stop a fish kill in progress.