COOK COUNTY — A growing population of northern pike in three Cook County lakes is making it too difficult for stocked trout to thrive.
The Minnesota Department of Natural Resources announced Monday, Jan. 29, that it plans to remove these lakes from its list of 159 designated trout lakes. Mulligan Lake and Jap Lake, also known as Paulson, are both located in the Boundary Waters Canoe Area Wilderness. Lizz Lake is partially in the BWCAW.
The three lakes were all formerly stocked with rainbow, brown and brook trout. These types of trout do not naturally reproduce in lakes, requiring regular stocking and stricter fishing regulations.
But the DNR said these lakes have been infested with northern pike. Shannon Fisher, fisheries population monitoring and regulations manager, said it’s not that the pike don’t belong there; they are native to Northern Minnesota. But historically, the lakes haven’t had large pike populations.
"These hatchery-reared trout are tasty morsels for northern pike,” Fisher said. “Pike are very effective at feeding on these fish, and so therefore it really isn’t a very effective management approach to continue to stock these trout.”
Fisher’s not sure how the large population of pike got there. They may have moved in from an adjacent lake during high water, been illegally stocked or have always been present in low numbers.
“Because of climate change, some of these cold-water lakes are becoming warmer and that actually can make them more suitable for pike,” he said.
According to Fisher, northeastern Minnesota’s cold, deep lakes are better protected from the effects of climate change. But the change in lake ecology has been more pronounced in central Minnesota from Mille Lacs to Detroit Lake. There’s even been some shifts in larger lakes farther north like Lake Winnibigoshish and Red Lake.
It remains to be seen exactly how warmer temperatures will affect those lakes and how that will impact anglers, Fisher said. But the changes in some central Minnesota lakes are indicative of what may come. Lakes that have historically supported large pike and walleye numbers are more dominated by small and largemouth bass, bluegill and crappie.
“There’s going to continue to be fishing opportunities and angling opportunities,” Fisher said, “but people’s expectations might have to shift a little bit in terms of the species that they’re targeting.”