Record Heat, Warm Water Lead to Fish Kills

Record Heat, Warm Water Lead to Fish Kills Click to Enlarge Photo:

Jul 13, 2012 at 8:25 am

WATERVILLE, MN (KNSI) – Last week's record-setting heat took a toll across the board in Minnesota, but in the southern part of the state, the fish population felt a big blow from the high temperatures.

Heat is being blamed by the Minnesota Department of Natural Resources for a number of fish kills in some state lakes over the past few weeks.

"Southern Minnesota has been affected more than the northern half of the state," Waterville area fisheries supervisor T.J. Debates said. "Generally our lakes down here are a little shallower, a little warmer...we really don't have a lot of in flow, fresh water coming into our lakes."

The warmer water has been especially difficult on northern pike throughout the state.

"Northern are more of a cool water fish species and the heat of last week really stressed them out," DeBates said. "They couldn't find any kind of refuge, therefore they get stressed out, then they die."

Another factor contributing to the fish kills is a low amount of oxygen in some waters thanks to both heat and blue-green algae.

"When blue green algae comes on it creates a lot of oxygen, but it also sucks up a lot of oxygen when it dies," DeBates said. "You know warm water holds less oxygen than cold water and therefore these fish...just couldn't find cool water refuge."

With plenty of warm temperatures still to be had this summer DeBates said if you come across a large fish kill, notify the DNR.

"Generally if they wash up on shore, what we tell people is that they can call us to let us know and we can figure out the next step depending on the severity of the kill," DeBates said.

While the region's most popular fishing lakes have been spared, officials warn that additional die-offs are possible as the summer progresses.

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