Public Forum Set on Plan to Restore Lake Michigan Lake Trout

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Fish biologists hope stocking lake trout in two deep water areas of Lake Michigan can help restore that native species. Great gains have been made in restoring lake trout to Lake Superior, as surveys by DNR fish crews show.  - wdnr pHOTOCLEVELAND, Wis. – Efforts to restore native populations of lake trout in Lake Michigan would shift to intensive stocking of the fish in deep water areas of the lake that are less affected by non-native invasive species, under a draft management plan that will be the topic of an upcoming public information forum.

The forum will be held August 11 beginning at 6 p.m. in the Lakeshore Room of the Lake Shore Technical College in Cleveland.

Intensive stocking of lake trout in deep water off Sheboygan in an area known as the mid-lake reef complex, and in Michigan waters in the vicinity of Beaver Island, are key components of the draft plan that Wisconsin and other Great Lakes states fish biologists hope will restore this native species where previous attempts have not. All lake trout stocked in Lake Michigan are produced by the U.S. Fish and Wildlife Service and stocked pursuant to management strategies developed by state and tribal agencies that work on the lake.

These deep water areas typically are less affected by alewives, an invasive fish species that recent research suggests may harm lake trout reproduction, according to Bill Horns, Great Lakes fisheries biologist with the Wisconsin Department of Natural Resources. There is evidence that alewives eat lake trout fry. Alewives contain a thiamin-destroying enzyme, thiaminase, so when they are consumed by lake trout they may also contribute to thiamin-deficiency in the lake trout offspring.

“The plan complements research by Dr. John Janssen of the University of Wisconsin-Milwaukee’s WATER Institute. Janssen, using remotely operated underwater vehicles, found lake trout are spawning in the mid-lake reef area and that some eggs survive to hatch,” Horns says. “That’s good news because spawning by stocked lake trout has been documented over the past half-century in Lake Michigan, but we can’t say that any of those eggs have survived to adulthood to help starting to rebuild naturally reproducing populations.”

Concentrating stocking in these deep water areas, which are mostly already designated as refuges off limits to anglers, will give the stocked fish the best chance of surviving and reproducing, he says. Increased control of sea lamprey populations is also necessary to help achieve the population densities required for sustained natural reproduction.

Stocking those two deep water areas, however, also means there will be fewer fish for stocking in Lake Michigan near shore areas in Wisconsin, Illinois, Michigan and Indiana.

“Those areas will still be stocked, but not at the same level as in past years,” Horns says.

Overall, the plan calls for the U.S. Fish and Wildlife Service to raise and stock 3.31 million yearlings and 550,000 fingerlings. That total is somewhat higher than in the recent past, “but we will be able to cut back if the stability of the forage base appears to be threatened,” Horns says.

The plan also calls for stocking three different strains of lake trout in an effort to increase genetic diversity and ultimately, natural reproduction. The Seneca Lake strain is from a New York lake of the same name and is believed to be less vulnerable to die from sea lamprey attacks than other strains. The Lewis Lake strain is derived from Lake Michigan ancestors and now resides in a Wyoming lake of the same name. The Apostle Island strain is taken from that area of Lake Superior.

Lake trout was a mainstay of commercial fishing in the early 1900s but had declined in all of the Great Lakes by the 1930s, and by the 1950s, lake trout were extinct in Lake Michigan although some native lake trout survived in Lake Superior. Likely factors for the lake trout’s demise include the introduction and proliferation of sea lampreys and overfishing, Horns says.

Efforts to restore lake trout have been ongoing since the mid-1950s when stocking was initiated. Starting in the 1960s, the sea lamprey control program carried out by the Great Lakes Fishery Commission suppressed sea lamprey. But the stocked lake trout, which survived well, have been fully restored only in Lake Superior.

FOR MORE INFORMATION CONTACT: Bill Horns (608) 266-8783