Winter fish die-off, or winterkill, is a natural process that happens from time to time in our area. This year the watershed and the City of Prior Lake have received reports of winterkill at Pike Lake, Crystal Lake, and Jeffers Pond (see photo).
Winterkill can happen when there are low oxygen levels in the water caused by factors such as:
- Early snow and ice
- Snow on the ice reduces sunlight, stopping plants from producing oxygen
- Shallow water levels
- Fish using up the available oxygen
After a winterkill event, residents can expect dead fish washing up on shore, foul odor due to decomposition, and an increase in scavenging animals. The Minnesota Department of Natural Resources (DNR) recommends either leaving the fish to decompose naturally or removing and burying them.
There are some benefits to winterkill, including the removal of invasive species such as carp. Lakes that experience a complete winterkill, such as Pike Lake this winter, receive a fresh start for their fish populations and may see an increase in water quality due the absence of carp.
The Minnesota DNR tracks winterkill; to report a fish die-off, call the DNR at 651-649-5451. More information can be found on the DNR website: https://www.dnr.state.mn.us/fisheries/fishkills.html
This article was first published on the City of Prior Lake’s website here.