(Provided by Indiana DNR)

Owners of shallow ponds and lakes should watch for fish kills this spring.

Because ice cover measured 20 inches thick on some northern waters, Indiana fisheries biologists anticipate receiving fish kill reports once the bodies of water thaw.

Shallow, weedy ponds are susceptible to winter kills. The most common cause of fish kills in Indiana ponds is suffocation due to the lack of oxygen.

Aquatic plants can produce oxygen only when sunlight is available. While some sunlight can penetrate clear ice, snow and thick ice can often block sunlight, resulting in dangerously low oxygen levels. Then, as aquatic plants naturally die during winter, plant decomposition consumes oxygen that fish and other aquatic life need. Once a winter kill begins, little can be done to stop it.

Pond owners who experience a fish kill or need advice on other pond-related issues can refer to Indiana's Pond Management Booklet at dnr.IN.gov/fishwild/3356.htm.

Pond owners can try to reduce the likelihood of a winter kill by installing an aeration system and removing snow from the ice when safe. Building ponds with depths greater than 10 feet also reduces the likelihood of a fish kill.

Drilling holes in ice does not prevent a fish kill.

Biologists do not expect significant fish kills at deep natural lakes and man-made reservoirs. The exception could be gizzard shad, a species that is vulnerable to prolonged cold weather. But because shad can diminish a lake's panfish population, a shad kill may improve fishing.

On March 23, Tom Bacula, District 1 fisheries biologist, received the first report of a shad kill on Bruce Lake in Pulaski and Fulton counties.

Lake residents and anglers who observe significant fish kills on public waters should contact their district fisheries biologist. Contact information for each district is in the 2015 Fishing Regulation Guide or at dnr.IN.gov/fishwild/3590.htm.