Summer’s Rising Heat Brings Fish Kills to Light

Posted on 11 June, 2014

Have you been noticing some not-so-pleasant smells around the lake shores? Don’t be alarmed! As strange as it sounds, the increase in temperature and the appearance of dead fish and decomposing plants around Minneapolis lakes have a direct correlation.

“Every spring, the rise in water temperatures and ensuing decrease in oxygen available for the fish, combined with the stress from spawning, can lead to fish kills,” said Deb Pilger, Director of Environmental Management for the Minneapolis Park and Recreation Board. “They will just die off and it does get a little smelly. There is also plant life in the lake that will decompose when it gets warm, and people may notice those smells.”

According to the Minnesota DNR, oxygen depletion can be a factor contributing to fish kills in lakes all across Minnesota. Heavy rains during early summer can cause unusual high runoff from fertilized lawns, athletic fields, golf courses and farm fields. The runoff carries nutrients into the lakes, which combined with hot weather, can accelerate the growth of algae and other plants.

“Typically, only those who own a home or cabin and have lakeshore access are aware of the fish kill odor,” said Pilger. “But because the paths and trails around Minneapolis lakes offers users such great access, more people notice it.”

Species affected are usually sunfish, crappies and bullheads and occasionally, largemouth bass and northern pike.

“We really try to keep an eye out for the spring and summer fish kills to make sure we get the fish cleaned up in a timely manner,” added Pilger.

A Few Things to Remember About Summer Fish Kills:

  1. Fish kills and plant decomposition happen yearly
  2. Fish kills occur not just in Minneapolis lakes but in many lakes in Minnesota
  3. Seasonal fish kills have no effect on the quality of the lake’s water for swimming or boating, the quality of the other fish in the lake or the ability to eat or consume fish from the lake

Contact

Questions from the media:
Robin Smothers 
Minneapolis Park and Recreation Board
612-230-6410
rsmothers@minneapolisparks.org