In a powerful sign of ongoing environmental recovery, a 35-inch, 16-pound lake trout caught near Sheboygan, Wisconsin, in May 2023 has been traced back nearly four decades to a conservation effort that began in the 1980s.
The trout, which turned out to be an astonishing 39 years old, was originally stocked in Lake Michigan in July 1985 after being hatched at the Iron River National Fish Hatchery in 1984. It now holds the title of the oldest lake trout ever recorded by the Great Lakes Mass Marking Program, according to the U.S. Fish and Wildlife Service (USFWS).
A Survivor of a Lost Era
This exceptional fish is one of only 39 lake trout documented to be over 30 years old since the marking program began in 2012. Most tracked lake trout are typically 20 years of age or younger. The fact that this individual not only survived but thrived for nearly four decades is a testament to the slow but steady success of lake trout recovery across the Great Lakes.
Once nearly wiped out from four of the five Great Lakes—Michigan, Huron, Erie, and Ontario—lake trout have faced a steep road to recovery due to overfishing and the devastating impact of invasive sea lampreys. The fish were once apex predators in these ecosystems, but by the 1960s, their numbers had collapsed, leaving only fragmented populations in parts of Lake Superior and Lake Huron.
Turning the Tide: Restoration Strategies
The recovery process began with the 1958 introduction of TFM, a chemical used to kill lamprey larvae. Sea lamprey levels have since been reduced by 90% in most Great Lakes regions, the USFWS reports. Alongside chemical control, hatchery stocking became central to repopulating the lakes with native lake trout.
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In recent years, efforts have expanded with more efficient breeding, tagging, and stocking strategies. Hatcheries like the Genoa National Fish Hatchery in Wisconsin and the Jordan River National Fish Hatchery in Michigan play a key role in producing millions of juvenile trout every year. These fish are then marked with coded wire tags and fin clips to monitor their survival and movement across the lakes.
In 2025 alone, Jordan River Hatchery raised over 2 million lake trout and cisco, despite weather-related challenges. Staff even ran the facility on backup generators during a massive power outage in April, ensuring fish received proper oxygenation and care.
Signs of a Sustainable Comeback
While Lake Superior’s lake trout population is considered fully restored, encouraging signs of natural reproduction have been recorded in Lake Michigan and Lake Huron. In fact, Lake Huron has seen such a strong return of young trout that stocking levels have been cut by 60% in the last five years.
These developments are not just biological milestones — they reflect decades of interagency collaboration and funding. The Great Lakes Fishery Commission, tribal authorities, and state and federal agencies all contribute to the lake trout recovery strategy. Funding from the Great Lakes Restoration Initiative supports critical components like hatchery modernization and mass marking systems capable of tagging up to 8,500 fish per hour.
What Makes Lake Trout Special?
Lake trout are native cold-water fish that can live incredibly long lives—some even reaching 70 years. They are known to grow large, with Michigan’s record catch weighing 61 pounds, 8 ounces. These fish are top predators and play a key ecological role by feeding on smaller fish like cisco, gobies, and smelt, as well as crustaceans and occasionally other small animals.
They prefer cold, deep waters, often diving beyond 200 feet during warmer months. In spring and fall, they migrate to shallower areas and reefs to spawn, often returning to the same sites year after year.
The Path Ahead: From Stocking to Sustainability
Restoring lake trout to self-sustaining levels remains the ultimate goal. According to the USFWS, success will be declared when artificial stocking is no longer needed. For now, the seasonal release of millions of juveniles continues.
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Each tagged fish offers insights into reproduction rates, migration patterns, and survival — all key data for measuring progress. The hope is that, like the 39-year-old trout caught off Sheboygan, many more will grow and thrive in a recovering Great Lakes ecosystem.
As conservation efforts continue, and hatchery innovations evolve, the story of lake trout in the Great Lakes stands as one of the most promising examples of species recovery in North America. Who knows — the next legendary fish may already be swimming beneath the surface, waiting to be discovered decades from now.
