Sea Lamprey

What is a Sea Lamprey?

The sea lamprey is a eel-like fish native to the northern Atlantic Ocean and the Baltic, western Mediterranean and Adriatic seas. In their native range, lampreys live part of their lives in salt water, but they have adapted to living entirely in fresh water in the Great Lakes. As adults they spawn in rivers and streams.
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How Did They Get Here And What Do They Do?

Sea lampreys invaded the Great Lakes in the early 20th century through shipping canals. Their eggs hatch into larvae that live on organic matter in stream bottoms until they transform into parasites that migrate downstream to lakes. The adult lampreys spend 12 to 20 months feeding on the blood of other lake-dwelling fish, until they are ready to travel upstream to spawn. The complete life cycle usually lasts five to nine years.

How Do We Stop Them?!

The large impact of the sea lamprey on Great Lakes commercial, sport and Aboriginal fisheries in the 1940s and 50s made Canada and the U.S.A to form the Great Lakes Fishery Commission in 1955. Since then the commission has led a program to assess and control the species using measures that target different stages of its life cycle. These include chemicals that only kill lamprey larvae, and barriers and traps that prevent adult lampreys from moving upstream to spawn. These do not harm other fish

Although it is basically impossible to eliminate the sea lamprey from the Great Lakes, ongoing efforts to control the species have reduced populations by 90%!

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How Do I Know If What I Found Is A Sea Lamprey And What Do I Do?


  • Cylindrical bodies are 30 to 76 centimetres long, and have no scales.
  • Leathery skin is grey to dark brown with dark blotches and a lighter belly.
  • Sharp teeth radiate around a rasp-like tongue at the centre of a large sucker mouth.
  • The fish has large eyes, two dorsal fins, no pelvic or pectoral fins, a single, mid-dorsal nostril, and seven obvious gill openings on each side.


  • Larvae are up to 18 centimetres long, blind and wormlike, with a black to pale grey body and a light underside.
  • In larvae four centimetres or longer, the first and second dorsal fins are distinctly separate.

If caught while fishing or is on a fish you have caught, do not throw it back. Just kill it and throw it in garbage or call Hotline 1-800-563-7711

References For Pictures and Information

Sea Lamprey | Ontario’s Invading Species Awareness Program. (n.d.). Retrieved May 24, 2016, from http://www.invadingspecies.com/invaders/fish/sea-lamprey/

Nightmare Fuel: Sea Lamprey Caught In New Jersey River | Geekologie. (n.d.). Retrieved May 24, 2016, from http://geekologie.com/2013/02/nightmare-fuel-sea-lamprey-caught-in-new.php

Braun, D. M. (2008, August 20). Bloodsucking Fish Follows Chemical Trail to Breeding Grounds. Retrieved May 24, 2016, from http://voices.nationalgeographic.com/2008/08/20/bloodsucking_lamprey/

By Marcus.N