Blood-sucking sea lampreys population decreasing in the Great Lakes

Updated: June 12, 2017

Sea lamprey population at 30-year low in Lake Huron and 20-year low in Lake Michigan.

Finally, some good news coming out of the Great Lakes: the blood-sucking, alien-resembling sea lamprey population is at a 30-year low in Lake Huron and a 20-year low in Lake Michigan.

The Great Lakes Fishery Commission, the chief organization in charge of controlling the lampreys, made the announcement last month.

In Lake Ontario, sea lampreys are also below target levels, a huge success for the organization.

“We still have work to do in Lakes Superior and Erie,” Robert Hecky, the commission’s chairman, said in a statement, “but sea lampreys are on a steady downward trend. We will always work aggressively to reach our targets in all lakes.”

According to the press release, sea lampreys are “one of the worst human-caused ecological disasters ever inflicted upon the Great Lakes.” They first infiltrated the Great Lakes through shipping canals and since 1939, have been feasting on local fish throughout the system.

Although lacking a jaw, sea lampreys have a suction mouth full of horn-shaped teeth and a razor-sharp tongue. They suction onto other fish, and then use their teeth and tongue to bore through the fish’s flesh. Once attached, the sea lamprey oozes an enzyme that prevents the blood from clotting.

Of the Great Lakes fish, sea lampreys target trout, whitefish, salmon, and sturgeon.

The Commission currently uses various techniques to control the population, including lampricides (a chemical that targets the larvae) and implementing traps and barricades.

“Before control, sea lampreys killed an estimated 103 million pounds of fish per year,” Hecky said. “Today, because of control, sea lampreys kill less than 10 million pounds of fish per year.”

“The control program provides fish a chance to survive long enough to spawn, be caught by humans, or live a natural life.”