Once near extinction, lake trout are officially recovered in Lake Superior
An adult lake trout. Fishery managers have declared the fish species recovered in Lake Superior. (Photo by Katie Steiger-Meister/USFWS)
by Kelly House (BridgeMichigan)
Seven decades after overfishing and invasive species nearly wiped them off the map, Lake Superior’s lake trout population has finally recovered.
That’s the conclusion of a binational group of tribal, US and Canadian species managers, who announced the milestone Wednesday in light of data that shows the self-sustaining population today is roughly as big as it was in the 1930s, before overfishing and invasive sea lamprey devastated the fish.
The group, known as the Lake Superior Committee, celebrated the recovery as testament to the progress that can be achieved when competing interest groups set aside their differences to work toward a common goal.
The recovery announcement may not be all that surprising to Lake Superior anglers — the local lake trout have been doing well for quite some time.
“It’s probably been 20 years that we’ve been in a pretty decent place,” said Dave Caroffino, a fisheries biologist in the Michigan Department of Natural Resources and vice chair of the Lake Superior Committee.
The crisis led the governments of the US and Canada to form the Great Lakes Fishery Commission, a body tasked with reining in overfishing and finding a way to control sea lamprey.
The game-changer: A 1958 discovery that the chemical compound 3-trifluoromethyl-4′-nitrophenol, or TFM, was capable of killing lamprey without significantly affecting other species. For decades since, rivers throughout the Great Lakes have been regularly treated with the chemicals.
Stricter fishing regulations and a hatchery-raised fish stocking program also aided the recovery, eventually allowing naturally reproducing fish to repopulate the lake.
What happens now
Seven decades may seem like a long time, but to Mattes, the lake trout recovery has been remarkably swift. The average lake trout doesn’t begin reproducing until it’s about 9 years old and lives to age 40. That means it’s only been five generations since the collapse.
Today, there’s no need to regularly stock lake trout in Lake Superior. But regular lampricide treatments will remain necessary.
“We’ve been able to drive [lamprey] down to 10% of their non-controlled level, but that 10% still takes a significant number of fish,” Mattes said. “So we need to keep that control up.”
Today, fishery managers estimate Lake Superior’s self-sustaining trout population is at least as large as it was in 1938, before sea lamprey arrived. Populations in the other four Great Lakes are not so robust.
Lake Trout recovery efforts are still ongoing in lakes Michigan, Huron, Erie and Ontario, with some encouraging signs in parts of lakes Michigan and Huron. But those lakes also contend with invasive mussels and alewives that can’t gain a foothold in Lake Superior’s frigid waters.
It’s unclear whether lake trout can thrive despite the onslaught. But Mattes said there’s reason to hold out hope.
“Lake trout are very resilient species,” he said. “If given the chance, they can do well.”
This article is being republished through a syndication agreement with Bridge Michigan. Bridge Michigan is Michigan’s largest nonprofit news service and one of the nation’s leading and largest nonprofit civic news providers. Their coverage is nonpartisan, fact-based, and data-driven. Find them online at https://www.bridgemi.com/.
You must be logged in to post a comment Login