The Decline of Lake Michigan Whitefish

State regulators say the commercial harvest of lake whitefish in Lake Michigan has reached its lowest level since 1990, and some fisheries biologists fear the species might largely disappear in parts of the lake.

In Wisconsin, the commercial harvest of lake whitefish has dropped from a peak of about 1.7 million pounds in 1999 to less than 200,000 pounds last year in all of Lake Michigan — a decline of nearly 90 percent.

The drop in harvest follows a declining trend of lake whitefish over the past two decades due to reduced survival of young fish, said Scott Hansen, fisheries biologist with the Wisconsin Department of Natural Resources. Hansen said federal, state and tribal agencies are meeting to discuss the issue this week.

“Without that replenishment of young fish into the population, we are seeing a pretty steep decline, and a continuous decline, in the abundance of lake whitefish in Lake Michigan,” Hansen said.

The most recent estimates show the spawning population had dropped to about 10 million pounds in 2021 — less than half the peak of 25 million pounds in the early- to mid-2000s.

While the fish face multiple challenges, Hansen said biologists believe invasive mussels are the greatest driver of their decline. The filter-feeding zebra and quagga mussels have disrupted the food chain by gobbling up food that larval whitefish rely on to survive.

Jason Smith, a Great Lakes fisheries biologist with Bay Mills Indian Community in Michigan, said he fears lake whitefish could disappear from parts of Lake Michigan within the next five to 10 years.

“The decline is incredibly steep, incredibly fast, and there is really no end in sight,” Smith said.

The decline has prompted state and tribal regulators in Michigan to set its most conservative limits for commercial harvest on record this year in central Lake Michigan, according to Bridge Michigan. In Wisconsin, Hansen said the DNR is updating its population estimates this year to inform harvest levels for the 2026 season.

As whitefish decline, commercial fishers adapt

Charlie Henriksen co-owns Henriksen Fisheries in Door County. When the fish reached peak levels in Lake Michigan and northern Green Bay, he said they harvested about 300,000 pounds of whitefish. Now, Henriksen said they catch about 150,000 to 200,000 pounds.

“Lake Michigan and northern Green Bay, there’s less fish up there, and they’re not there all the time like they used to be,” Henriksen said.

The decline has prompted the business to shift more to processing fish for sale at local restaurants. It’s also changed when and where they harvest fish. As numbers have declined in Lake Michigan, Henriksen said they primarily fish now in southern Green Bay due to a resurgence of the fish there beginning around the early 2000s.

By 2021, Hansen said the spawning population of lake whitefish in Green Bay was nearly double that of Lake Michigan, at roughly 19 million pounds. After being wiped out there in the late 1800s, the revival of the fish in the bay was due in part to more whitefish spawning in the Menominee, Oconto, Peshtigo and Fox rivers.

Hansen said the self-sustaining population might have been driven by remnant fish populations in Green Bay or a spillover of whitefish from Lake Michigan when fish were at their peak. He added that efforts to clean up historical pollution from paper mills following the passage of the Clean Water Act in 1972 also played a role in providing good spawning conditions.

Michigan tribes, agencies seek to replicate success in Green Bay

In Michigan, tribes are working with the Nature Conservancy and Michigan Department of Natural Resources to replicate those results by stocking whitefish in rivers that flow into Lakes Michigan and Huron. But Smith said he doesn’t expect it to save whitefish. He noted most whitefish in the lake are more than 20 years old, and they live about 30 years.

“It’s going to add a handful of young fish back to the population to kind of keep that bridge going, so that we might get to a time when the lake is a better fit for whitefish,” Smith said. “It’s just the right thing to do to bring back these river-spawning life histories. We were the cause of them disappearing.”

Lake whitefish have declined up to 80 percent in Lakes Michigan and Huron due largely to invasive mussels introduced through the ballast water of ships on the Great Lakes. The fish also face threats from habitat loss, pollution and warming winters due to the use of fossil fuels that contribute to climate change.

Henriksen noted that researchers at the University of Wisconsin-Milwaukee and others are experimenting with removal of quagga mussels near Milwaukee, Sleeping Bear Dunes National Lakeshore and Muskegon, Michigan. Early results show that mussels don’t come back right away.

Meanwhile, Hansen said the DNR plans to present updated harvest levels to the Natural Resources Board for approval by the end of the year. Both Henriksen and Smith say overfishing is not the issue.

“This is not an over-harvest problem,” Smith said. “This is an ecosystem problem.”

Listen to the WPR report

Decline of whitefish in Lake Michigan sparks fears that the fish might disappear was originally published by Wisconsin Public Radio.