Ice melt leads to dead fish surfacing on numerous area lakes

REGIONAL — As the ice melted off many of southwest Minnesota's shallow lakes last week under summer-like temperatures, the impact of a harsh winter with deep snowpack became even more evident.

Nearly two months ago, Minnesota Department of Natural Resources Windom Area Fisheries Superintendent Ryan Doorenbos speculated there could be significant winter kill to fish species on numerous lakes in his district. The speculation was based on low oxygen levels measured from water bodies. Once the oxygen level gets below 2 parts per million, the likelihood of fish having enough oxygen to survive is minimal.

"Winter kill is on the spectrum from a few fish to windrows of dead fish," Doorenbos reported to The Globe on Tuesday morning. "(Lake) Shetek had windrows of dead fish. Both north and south Fulda Lake were hit pretty hard. Fox Lake, also in Murray County, similar deal — they were hit pretty hard with winter kill."

If there could be a positive in the amount of dead fish, Doorenbos said on both Fox Lake and Lake Shetek, the largest percentages of dead fish were common carp and bigmouth buffalo fish. Still, there were some walleye, northern pike and catfish among the species found dead in the water.

"About 14 different lakes in my Windom area had some partial winter kill," Doorenbos said. "The degree to the kill is unknown at this point."

While the DNR Fisheries unit will inspect area lakes more thoroughly through fish netting and electrofishing to gauge the severity of the fish kill, they won't be able to get out for a while.

"We’re starting our spring work with northern pike and setting nets for walleye egg take," Doorenbos shared. "There are other priorities at the forefront."

Related to that work, he said northern pike will be restocked in lakes this fall, and the walleye egg take planned to take place during the next week should result in walleye fry stocking in lakes throughout the area around the time of the 2023 Minnesota fishing opener.

With the lakes that suffered winter fish kills, Doorenbos said it creates an opportunity to reset the biomass in a lake and create a more desirable fishery for anglers.

"The fish restocking goes better when you have a winter kill," he noted.

In Nobles County, Okabena-Ocheda Watershed District Administrator Dan Livdahl said both Lake Ocheda and Lake Bella have had significant numbers of dead fish this spring.

Lake Bella had extremely low dissolved oxygen levels from January through February, and Lake Ocheda had three consecutive weeks of dissolved oxygen levels below 1 ppm.

Livdahl had anticipated a lake-wide fish kill on Bella, and from what he's seen along the shoreline, the dead fish are primarily common carp and bigmouth buffalo. Yet, when he was out at the Ocheda dam late last week, he saw both carp and buffalo species trying to get into Lake Ocheda from the Ocheyedan River. That tells him Lake Bella didn't have a total fish kill.

"It wasn't like hundreds or even thousands like you have some years — just a bunch of fish," he said.

In Lake Ocheda, Livdahl said he thinks there is a significant fish kill, but it's hard to say. The lake experienced a severe fish kill two years ago with windrows of dead fish washing ashore. It's possible this past winter took care of what fish species remained in the lake.

Still, he noted that pelicans have been on Lake Ocheda and appear to be actively fishing, which tells him some fish survived.

Two years ago, during the significant winter kill, Livdahl said dead fish continued to wash toward shore for about a month after the ice-out. He intends to keep an eye on the shorelines for the next several weeks to see how many more dead fish will surface.