Lake Champlain began killing invasive sea lampreys in 1990; native lake trout survival rose 25%, and Atlantic salmon returns to the main lake fishery tripled

Picture a fish fit to star in a B-grade horror film, a slimy, eel-like creature with a round, tooth-ringed maw that attaches itself to bigger fish like a juice box straw and drains them of their lifeblood. It's the sea lamprey, and for much of the 20th century, the parasitic leech was doing a slow, thorough job of devastating one of America's oldest lakes.

Lake Champlain, the 120-mile-long waterway snaking between Vermont, New York, and Quebec, was once a premier fishing destination, until native lake trout and the anadromous Atlantic salmon were nearly wiped out by lampreys that had invaded the ecosystem from connected waterways, though, as the record shows further down, “invaded” is itself contested. According to a 2003 study titled “Sea Lamprey Control in Lake Champlain,” published in the Journal of Great Lakes Research, this rampant wounding of fish necessitated an aggressive, experimental lake-wide lamprey control program beginning in 1990 that actually worked, and continues to work three decades later.

The experiment that actually paid off


In 1990, the U.S. Fish and Wildlife Service launched an eight-year experimental control program with the help of New York and Vermont state agencies, one that involved treating tributaries with specialized lampricides and laying down barriers to impede lamprey spawning migrations. The same Journal of Great Lakes Research study on the experimental program reveals that between 1989 and 1997, spawning-phase lamprey captures in treated tributaries fell by an average of 80 to 90%, lake trout survival rates of three- to four-year-olds jumped 25% (statistically significant) over that same window. Atlantic salmon returns to the lake’s main sport fishery roughly tripled across that period. Put another way: A lake that had all but lost a signature species of fish saw them slowly return within a single decade.

It was more than just a pilot program

A lot of experimental programs quietly fade away after an initial round of grant funding, but not this one. Most recently published figures from Lake Champlain Basin Program (LCBP) shows a benefit-to-cost ratio of approximately 3.5:1, suggesting that every dollar spent on the lamprey control program ultimately provided a three-dollar benefit to the local economy through increased tourism, recreational fishing, and related expenditures. A ratio of that sort is likely to keep a program running long after the word "experimental" is removed from its tagline.

It also continued to reap dividends, both in the fish population and the regional budget. A recent U.S. Fish and Wildlife Service account of the program notes that lamprey wounding rates on lake trout fell from 99 per 100 in 2006 to just 23 per 100 by 2022, while the agency has since invested about $1.7 million a year in the effort, which it says generates close to $6 million in fueling a regional economic ecosystem. Lake trout, once entirely dependent on hatchery breeding, are now self-sustaining: stocking formally ended after a final release in spring 2025, when the Lake Champlain Fish and Wildlife Management Cooperative across New York, Vermont, and federal fisheries agencies, confirmed the wild population no longer needed hatchery augmentation.

A genuine caveat and why this should matter

None of this came without costs or compromises; that's for sure. The 2003 study reports that lampricide treatments took a toll on amphibian, mollusk, and indigenous lamprey populations as well. Sea lamprey nests saw their numbers fall less steeply than the drops observed in trap indices, suggesting that while the species suffered, its decline wasn't uniform or absolute. And the “invasive” framing itself is contested: the same body of research this article draws on documents an ongoing scientific debate over whether Lake Champlain’s sea lampreys are a 19th-century canal introduction or a landlocked population that has persisted since the last glaciation. Genetic studies since the mid-2000s have leaned toward a native, postglacial origin, even as fisheries agencies continue to manage and describe the population as invasive/nuisance. Either way, researchers agree the wounding impact on trout and salmon is real and severe. It's a mixed record of sorts, but one that continues to show dividends after decades of careful, costly chemical treatment, and not one that should be blindly applied to other invasive-species issues.

For a country currently fighting an uphill battle against invasive carp in the Mississippi, feral hog incursions across the South, and the spreading menace of the spotted lanternfly up and down the Eastern Seaboard, this example serves as one small reminder of what years' worth of committed funding and research can achieve. In an era where the news cycle seems to specialize in bleak environmentalism, a single parasitic insect getting outsmarted by human perseverance is a small victory worth celebrating.