Sea Lamprey

Sea Lamprey

Sea lamprey 

(Petromyzon marinus)


Sea Lampreys have significantly reduced the number of sportfish in the Great Lakes, as only one in seven fish survive an attack. Their predation on valuable fish stocks was so high in the 1940s it became a key factor in the collapse of the Great Lakes ecosystem and economy that it supported. Sea lampreys killed more than 100 million pounds of Great Lakes fish annually, five times the commercial harvest in the upper Great Lakes. These parasitic fish have long slender bodies somewhat resembling an eel, with a very distinctive mouthpiece that has rows of teeth in a circular pattern. They latch onto other fish and use their teeth to scrape away scales and gain access to blood, they then feed on the blood and then leave the host. The host will die the majority of the time after a sea lamprey attack. These invasive fish has no scales but rather a cartilage outer body, like a shark.


They are found in most of the great lakes and in parts of the St Lawrence. While they are native to the Atlantic Ocean and Mediterranean/Adriatic seas they were introduced in the early 1900s through constructed shipping routes.

Impacts & Control

These invasive fish do cause economic issues as they kill fish that could otherwise be caught and sold. Not to mention the ecosystem damage of losing large populations of native fish. However, the greatest impact of the Sea Lamprey is its role in reducing Sturgeon populations. Over the last few hundred years, Sturgeon populations were decimated via overfishing and “Pest control”, now we are trying to bring these gentle giants back to stable population levels but the Sea Lamprey is making the situation worse.

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