Winterkill affecting some area lakes
Something fishy is going on at North Center Lake in Center City — dead fishy, to be more precise.
North Center is one of the area lakes affected by winterkill.
Chisago County Administrator Bruce Messelt said the county has collected about 12.5 tons of dead fish, mostly carp, out of the lake and transported them to a landfill in Mora.
Roger Hugill, area fisheries manager with the Minnesota Department of Natural Resources, said this is the first recorded winterkill in North Center since the 1960s.
He explained that a number of factors combine to result in a winterkill.
“The depth of the lake makes a difference,” he said. “The critical thing is you get early ice, and heavy snow cover that shades the phytoplankton and algae, so they die, and they aren’t producing oxygen anymore.”
He added that lakes that are very nutrient rich are at a higher risk for winterkill because biological activity, or respiration, uses up oxygen.
“You might say, ‘Why carp?’” Hugill said in relation to the majority of the fish that died in North Center. “It could have been the location they were staying in, or maybe they were weak because of a virus or something.”
Carp aren’t game fish like walleye, bass or bluegill, so some people might see the winterkill as a good because it cleared out a population of fish people don’t want to catch, but reducing the amount of one fish species in a lake can have repercussions.
“When you create a void, sometimes other fish fill in the void, like black bullhead, because they’re very winterkill resistant,” Hugill said. “Sometimes we see a spike in the bullhead population after a winterkill.”
However, he said the DNR is introducing more game fish into North Center to try and avoid an increase in black bullhead.
He noted fish populations in Minnesota lakes are often quite resilient, and they tend to reproduce quickly when reintroduced.
“The ones that survive will get big real fast,” he said. “In the next couple of years, you’ll see some large crappies and bluegills because they grow fast.”
Hugill added that some other area lakes, such as Little Lake and Spider Lake, also had occurrences of winterkill, and the DNR is testing other lakes to find out if it will have to restock the lakes.
“We cover Pine, Kanabec, Isanti and Chisago counties,” Hugill said. “This year was a pretty tough winter. We had winterkill in lakes in all four counties.”