Michigan Lakes Hit by Fish Die-Off. What’s the Cause?

Why are residents finding so many dead fish in Michigan's inland lakes?

More importantly, when do we start to worry? The Michigan DNR has some insight as to what's happening across our lakes and ponds and why it's not necessarily cause for concern. However, we can all agree on one thing:

Get our free mobile app

This stinks!

If you haven't been on your local community's Facebook group lately here's what you're missing: residents ranging from Hamilton to Howell are finding large amounts of dead fish in nearby bodies of water and they can't seem to get to the bottom of it. In fact, in some cases its downright alarming!

One West Michigan mom shared her recent experience on social media and included a photo of a pile of dead fish on the shoreline:

Does anyone know what happened to the wildlife in Sink Lake here in Hamilton, MI? [My daughter's] dad brought her up by the lake to try and show her how to skip rocks and we came across this...my daughter was almost in tears...This is scary and hope to find answers

I definitely can understand how that might be traumatizing for anyone, child or adult, but the Michigan DNR claims there's a completely logical reason for this:

Winter kill

In an interview with The Detroit Free Press  Aaron Switzer, DNR fish production program manager says,

The fish actually suffocated from a lack of dissolved oxygen from decaying plants and dead aquatic animals under the ice.

"Winter kill" is a natural phenomenon and occurs each year as snowpack and frozen waters reduce the amount of dissolved oxygen in lakes and ponds over the winter. Because there is not enough sunlight to reach vegetation at the bottom of the water there is less oxygen supply for fish, frogs, and crayfish who may perish during winter. Adds the DNR,

A good midwinter thaw... often recharges the lake's oxygen supply by means of photosynthesis and melt water. Conversely, a prolonged winter, with continuous snow cover and late ice-out, increases the chance of winter kill

Winter kill is just a natural part of the ecosystem and occurs each winter, but we don't typically notice until the first thaw of spring; only then can we asses the true severity of winterkill. DNR officials say if residents are noticing an uptick in dead fish this year it is simply due to the harsh winter we had. No cause for concern here!