The sea lamprey’s journey from the ocean into the Great Lakes

The “Vampire of the Great Lakes” has remained a dangerous invasive species for more than a century. Sea lamprey, are given their nickname for the way they feed. They latch onto a host fish with their suction cup like mouth and drain it.

Sea lamprey’s mouth

Sea lampreys originate from the Atlantic Ocean and began to enter the Great Lakes in the 1800s. Niagara Falls served as a natural barrier preventing the species from entering the upper Great Lakes besides Lake Ontario.

According to the Great Lakes Fishery Commission, they were first found in Lake Ontario in the 1830s. Then, after improvements were made in 1919 to the Welland Canal, they were found in Lake Erie. The improvements made to the Welland Canal made it possible for the sea lamprey to infiltrate the other lakes.

After reaching Lake Erie, sea lamprey began to quickly spread to the other Great Lakes; appearing in Lake Michigan in 1936, Lake Huron in 1937 and Lake Superior in 1938. Sea lampreys began to negatively effect the environment and other species in the late 1940s as their numbers rapidly spread across the lakes.

Sea lamprey thrive in the Great Lakes because of an abundance of host fish, which is how they feed, a lack of predators and their high reproductive rate.

The Great Lakes Fishery Commission reports that lampricide is primarily used to kill larval sea lamprey. A combination of barriers and traps are used to prevent adult sea lamprey from migrating and reproducing.

These techniques, although it has taken time, have decreased the population of sea lamprey throughout the Great Lakes. Lake Erie has faced the most difficulty with eradicating the invasive species but have still sharply decreased since they were first introduced.


In the 1950’s and 60’s, scientists began to work on lampricide. The main goal was to find a chemical to specifically kill larvae of sea lamprey without furthering damage to the environment or other species. Lampricide is used in tributaries, where sea lamprey larvae burrow for 3-10 years, before they migrate into the Great Lakes where they can do real harm to the ecosystem.

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