DNR to change trout stocking in Lake Superior
To protect Lake Superior’s naturalized rainbow trout population, genetically screened steelhead-strain fish, originating from wild runs in the big lake itself, will replace the hatchery-raised Kamloops trout strain the Minnesota DNR now stocks to bolster fishing opportunities near Duluth, the DNR said in a news release Thursday, March 15.
New advances in genetic testing confirm Kamloops interbreed with wild rainbow trout. When that happens, fewer young survive and the overall steelhead population is reduced.
The change from Kamloops to stocking wild-sourced steelhead lets fisheries managers improve fishing opportunities on area streams while continuing the rehabilitation of the wild fish population, the DNR said.
Since 1976, the DNR has stocked the Kamloops strain of rainbow trout in Lake Superior’s waters near Duluth. Stocking increased angler opportunity and reduced harvest pressure on wild steelhead. The action helped Lake Superior’s wild rainbow trout recover from the detrimental effects of invasive sea lampreys and overfishing.
Despite only localized stocking, the stocked Kamloops genetics have shown up in samples taken from many North Shore streams, the Wisconsin Bois Brule River and Michigan waters of Lake Superior.
Numerous genetic studies on the North Shore all point toward the negative impacts of interbreeding on wild steelhead populations, but DNR researchers were never able to confirm genetic interbreeding in the wild even with genetics work done as recently as the 1990s.
The steelhead the DNR stocks will have an adipose fin clipped off, just like Kamloops did. That process, which doesn’t harm the fish, allows anglers to easily determine what can be harvested. Unclipped, wild steelhead will continue to remain catch-and-release only – as they have been since 1997. Because of this, the stocking change means anglers will see the same harvest regulations.
More information about the Lake Superior fishery, including the 2016 Fisheries Management Plan for the Minnesota Waters of Lake Superior, can be found on the DNR website at mndnr.gov/areas/fisheries/lakesuperior.