Dead fish on Harsens Island might result from winter kill

Photos posted on a Facebook page show hundreds of dead fish floating in an area of Harsens Island, but state wildlife officials believe the fish died from winter kill.

The photos were posted on the Harsens Island Michigan Facebook page at https://www.facebook.com/harsens.island.mi/photos/pcb.920712391419638/920711911419686/?type=3&theater.

Todd Wills, Lake Huron-Lake Erie Area research manager at the Michigan Department of Natural Resources Lake St. Clair Fisheries Station in Harrison Township, said in an e-mail that station staff had not been aware of the photos.

"I talked to John Darling, DNR wildlife technician at the St. Clair Flats Wildlife Area on Harsens Island," he said in the email. "John advised that this isn’t Krispin Drain, but rather an area that is referred to as 'dump woods slough.' 

"He said winter kill happens in this location every year. I suspect that’s the case again this year; with the recent thaw these dead fish likely rose to the surface and then refroze after the cool down."

More:

Anglers enjoying early ice fishing

According to the DNR's web site, shallow lakes with excess amounts of aquatic vegetation and mucky bottoms are prone to winter kill. The fish suffocate from lack of dissolved oxygen.

According to information on the web site, during periods of prolonged ice cover, the lake is sealed off from the atmosphere and cannot be recharged with oxygenated air. Ice and snow further reduce the amount of sunlight reaching aquatic plants, thereby reducing photosynthesis and oxygen production. On-going consumption of oxygen depletes the supply of oxygen stored in the lake when the lake froze over.

Shallow, productive lakes are at a disadvantage because they have a low storage capacity and high rates of oxygen-consuming decomposition, according to the DNR.

Wills said Darling went out to check the area Friday morning and "provided photos of dead fish that are similar in number and species to those that were posted on Facebook.

"The fish are too old for us to reliably test for disease (we need live or 'fresh' dead fish), but we will keep an eye and ear out for other fish kill events in this area," he said in his email.

Fore more information about fish kills, go to http://www.michigan.gov/dnr/0,4570,7-153-10364_52259-119822--,00.html.

Contact Bob Gross at (810) 989-6263 or rgross@gannett.com. Follow him on Twitter @RobertGross477.