The battle against invasive species is rarely won, but in the Great Lakes, officials are declaring an unprecedented triumph. After decades of destruction caused by the predatory sea lamprey, a new selective lampricide has successfully reduced their population by 90-95%, according to National Geographic.

The sea lamprey, a parasitic fish resembling an eel, arrived in the Great Lakes more than a century ago, wreaking havoc on native fish species and the ecosystem. Known for their voracious appetite, sea lampreys consumed over 100 million pounds of fish annually, outcompeting both humans and other predators.

“This is an unprecedented victory anywhere on the planet,” said Marc Gaden, executive secretary of the Great Lakes Fishery Commission. “You have a species this destructive, this geographically widespread, and yet still able to be controlled using a selective technique. It saved the Great Lakes fishery.”

A Targeted Solution That Worked

The key to this success lies in a highly selective lampricide, developed by scientists from the University of Michigan and the Hammond Bay Biological Station. This chemical targets sea lampreys without harming native fish or other wildlife.

Unlike broader eradication methods, which often disrupt entire ecosystems, this lampricide specifically eliminates sea lampreys at critical stages in their life cycle. It took researchers seven years to perfect the formula, which has now proven to be the most effective tool in managing the invasive species.

“It’s not rocket science to kill fish. Fishery managers actually do it all the time,” Gaden explained. “What’s really hard is killing just what you’re after and leaving everything else intact.”

Why Sea Lampreys Were So Destructive

Sea lampreys are parasitic creatures that latch onto other fish, draining their blood and body fluids. Their impact on the Great Lakes ecosystem was catastrophic, rivaling some of the most destructive invasive species in history.

“At their height, sea lampreys were consuming over 100 million pounds of fish,” said Greg McClinchey, legislative affairs and policy director for the Great Lakes Fishery Commission. “To put that into perspective, they were outcompeting humans for that resource. They were more damaging to the natural ecosystem than people, and that’s pretty hard to do.”

Attempts to control sea lamprey populations included releasing sterile males to disrupt reproduction and setting up barriers to limit their movement. While these methods offered some success, the lampricide has emerged as the definitive solution to the problem.

A Model for Future Efforts

The near-eradication of sea lampreys in the Great Lakes is a rare example of an invasive species being brought under control without collateral damage to native ecosystems. For other invasive species, such as lionfish and snakeheads, eradication often feels impossible, with officials instead aiming to control populations.

The success of this program offers hope and a potential blueprint for managing other invasive species around the world. As Gaden emphasized, the ability to selectively target a destructive invader while preserving the natural ecosystem is a groundbreaking achievement.

This victory not only restores balance to the Great Lakes but also highlights the importance of innovative science in addressing the challenges posed by invasive species.