Species and Origin: It is an eel-like fish that attaches with its suction-cup-like mouth to fishes, and feeds on their blood. Adults are tubular, mottled brown or black with a grayish belly, scaleless, and usually 12-20 inches long. Their mouth has teeth in concentric circles. Sea lampreys are native to the Atlantic Ocean, Lake Ontario, and the St. Lawrence River.
Impacts: It is historically the most devastating invader in the Great Lakes. A single sea lamprey can kill 40 lbs. of fish during its adult lifetime. Before control efforts, lake trout populations were drastically reduced or extirpated. Anglers might see wounds or scars on sport fish they catch.
Status: Present throughout the Great Lakes and many tributaries. A U.S. and Canadian control program has successfully reduced sea lamprey populations by 90%. Control costs average $16 million annually, and protect Great Lakes fisheries valued at $4.5 billion per year.
Means of spread: They spread into the other Great Lakes via canals that bypassed natural barriers.
Where to look: Each spring, adults migrate upstream in tributaries of the Great Lakes where spawning pairs may be observed making nests.
Regulatory Classification: It is a prohibited invasive species (DNR), which means import, possession, transport, and introduction into the wild is prohibited.
How can you help?
More on lamprey control from Minnesota Sea Grant