Thunder Bay's New Weapon Against the 'Vampire Fish': A Triumph for Great Lakes Ecology

A silent, ancient predator, often dubbed the "vampire fish," has long haunted the depths of the Great Lakes, preying on native fish populations and threatening the region's delicate ecosystem. But in Thunder Bay, Ontario, a new sentinel stands guard: a state-of-the-art sea lamprey trap on the Current River, marking a significant stride in the ongoing battle against this formidable invasive species.

For decades, the sea lamprey (Petromyzon marinus) has been a devastating force.

These eel-like creatures, native to the Atlantic Ocean, invaded the Great Lakes through shipping canals in the early 20th century, finding a vast, unprotected larder of native trout, salmon, whitefish, and other species. Latching onto their hosts with a suction-cup mouth filled with razor-sharp teeth and a rasping tongue, they drain their victims of blood and bodily fluids, often leaving them dead or severely weakened.

The economic and ecological impact was catastrophic, nearly wiping out commercial fisheries in the mid-1900s.

Now, thanks to the collaborative efforts of Fisheries and Oceans Canada, the Great Lakes Fishery Commission, and the Ontario Ministry of Natural Resources and Forestry, Thunder Bay is home to an advanced control measure.

The new trap, strategically located to intercept migrating lampreys, represents a leap forward from previous methods. Unlike traditional barriers or widespread application of lampricides – chemicals that target lamprey larvae – this trap offers a more precise and environmentally friendly approach.

The design of the Current River trap is ingenious.

It allows for the safe passage of native fish species upstream and downstream, while effectively capturing the migrating adult sea lampreys. Once trapped, these "vampire fish" can be counted, studied, and then humanely removed from the ecosystem, providing invaluable data for researchers and reducing the reliance on chemical treatments.

It’s a win-win, ensuring the health of the river while precisely targeting the invasive threat.

The Thunder Bay Historical Museum Society has even played a role in educating the public, offering rare glimpses of captured sea lampreys. This public engagement is crucial, transforming an abstract ecological threat into a tangible experience and fostering a deeper understanding of the conservation efforts underway.

The fight against the sea lamprey is a testament to persistent, multi-generational dedication.

Control programs, which began in the 1950s, have already achieved remarkable success, reducing sea lamprey populations by an estimated 85 to 90 percent. This new trap in Thunder Bay builds upon that legacy, bolstering defenses and enhancing the precision of these critical management strategies.

As the "vampire fish" continue their ancient migration, the new Current River trap stands as a beacon of hope, safeguarding the future of the Great Lakes' vibrant aquatic life.

It's more than just a trap; it's a symbol of human ingenuity and unwavering commitment to preserving one of North America's most precious natural treasures.