An eel-like parasitic fish known as the sea lamprey, native to the Northern Hemisphere but invasive to the Great Lakes, has seen fluctuating populations in recent years. While a surge occurred during the COVID-19 pandemic, authorities are working to manage the situation.
Left: Close up view of an open sea lamprey mouth with teeth with sharp teeth visible. Right: Satellite image of the American Great Lakes – Lake Superior, Lake Michigan, Lake Huron, Lake Erie and Lake Ontario. (iStock/Planet Observer/Universal Images Group via Getty Images)
The Great Lakes Fishery Commission, a joint effort between the U.S. and Canada, is tackling this issue. They employ a lampricide, a targeted pesticide, to control lamprey larvae in streams. Logistical hurdles during the pandemic hampered these efforts, leading to a population increase. The commission observed a rise in lamprey numbers in 2022 and anticipates a similar trend in 2023.
A lake trout caught from Lake Superior was bitten by sea lamprey. Researchers analyze the attacked fish during an annual spring population survey on May 8, 2018, in Duluth, Minnesota. Sea lamprey kill trout, sturgeon, whitefish ciscoes, burbot, walleye, catfish, salmon and more. (Jerry Holt/Star Tribune via Getty Images)
Despite control measures, anglers continue to encounter these parasitic fish and observe their impact on other species. While their appearance is alarming, sea lampreys are not known to be harmful to humans, and fish bearing lamprey wounds remain safe to eat. Historically, sea lampreys have been a food source in some cultures.
Sea lamprey, also known as Petromyzon marinus, resemble eels with the species slim build. The parasitic fish has two close dorsal fins, seven gill openings, a large round mouth with sharp teeth and a rasping tongue. (iStock)
These ancient creatures, with their distinctive features like rows of sharp teeth and a rasping tongue, can significantly impact fish populations, potentially killing over 40 pounds of fish throughout their lifespan. Having entered the Great Lakes through shipping canals in the 1920s, they remain a persistent challenge. The Great Lakes Fishery Commission's control program has achieved significant success, reducing lamprey numbers by 90-95% and safeguarding the valuable Great Lakes fishery. While complete eradication is unlikely, ongoing control efforts are crucial to maintaining the health and balance of this ecosystem.
