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Sea Lamprey

The sea lamprey has 7 gill openings and a distinctive disk-shaped mouth. Photo credit: Lee Emery, US Fish and Wildlife Service,

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Common Name: Sea Lamprey
Scientific Name: Petromyzon marinus
Origin: Atlantic Ocean


The sea lamprey is an aggressive parasitic fish that resembles an eel. This species has two dorsal fins, no paired fins, seven gill openings, and a very distinctive disk-shaped mouth with sharp, curved teeth and a rasping tongue. Their scaleless body is a mottled gray to black color that fades to a silver-white coloration on the underside. Adult sea lampreys are generally 12-20 inches in length.


Juvenile sea lampreys live in streams and rivers, and then move to large freshwater lakes or the ocean. Breeding adults then return to freshwater streams and rivers.


This species will attach to a fish and drain its bodily fluids resulting in a 40-60% mortality rate from blood loss, infections or stress. Sea lampreys feed on salmon, various species of trout, walleye, sturgeon and other fish species that are important to sports fishing industries, cultural practices and the ecosystem.


The primary method in the control of sea lamprey populations is the use of a lampricide known as TFM in the freshwater tributaries where they spawn. TFM kills the lamprey larvae before they are able to attach to a host fish and has been demonstrated as a successful method of control. Other methods of management include traps, sterilization, and both physical and electric barriers.


A large, round wound or scar can be found on fish that have had a sea lamprey attached to them.

Regional Distribution


WNY PRISM Priority

Tier 2 – Eradication

Invasive Species Priorities – Tier Chart


Sea lampreys were historically found in Lake Ontario as it is connected to the Atlantic Ocean via the St. Lawrence River. Sea lampreys were found in Lake Erie for the first time in 1921, likely the result of the Welland Canal that created a trade corridor between Lake Ontario and the remaining Great Lakes.

The sea lamprey is a prohibited species in New York State – for more information on Prohibited and Regulated Species, visit

Additional Resources

Great Lakes Fishery Commission
NYS Department of Environmental Conservation