Harsh winter threatens fish population

Thick ice, snow expected to cause higher winter kill
Harsh winter threatens fish population

At the Madison Fishing Expo, you’d never know it was still the middle of February.

“It’s been a grueling winter. We’re all ready for spring.” said fisherman Jim Gasaway.

The brutal winter weather and freezing conditions have made for a better than average ice fishing season. Thick ice, as thick as 3 feet in some places, on many Wisconsin lakes has allowed anglers to venture out farther onto lakes than in previous years, but the weather has made things tough.

“This year more than previous, I’ve heard many ice fishermen say it’s just been too cold to fish,” Gasaway said.

But the frigid temperatures and thick ice has Department of Natural Resources officials on high alert for a condition called winter kill.

Winter kill affects shallow, fertile lakes. Those conditions apply to many in the southern portion of the state. It occurs when sunlight is prevented from reaching underwater plants by thick ice and dense snow cover.

“It’s a combination of that thickness of ice and depth of snow and it’s essentially shutting the lights off on the plants that are under the water,” said DNR Fisheries Ecologist, Paul Cunningham.  

Without light, the plants are unable to produce the oxygen that fish need to survive during the winter months which could end up killing fish and depleting the population come spring.

“It’s been an unusually long winter and we may be surprised by a few more winter kills this spring,” Cunningham said.

Winter kill is not an uncommon occurrence. In 2013, the DNR said 14 lakes statewide reported winter kill.

DNR crews aerate lakes to prevent winter kill, but Cunningham said the department can’t get to all the lakes at once. He added they won’t know the extent of the kill until the ice melts.