What Exactly Is A Sea Lamprey?

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What Does A Sea Lamprey Really Mean?

The sea lamprey, an old Atlantic fish that caused a lot of damage in the Great Lakes, might be the first species to come into the United States without permission.

The sea lamprey is a parasitic fish that lives in the northern and western Atlantic Ocean. It is one of the oldest kinds of vertebrates. Lampreys are sometimes mistakenly called “lamprey eels” because their bodies look a lot alike.

Arctic Lamprey, Yukon River near Kaltag. Photo by Randy Brown, USFWS

There are no scales, fins, or gill covers on lampreys like there are on “bony” fish like trout, cod, and herring. Their bones are made of cartilage, just like sharks’. They breathe through seven sets of tiny gill holes behind their eyes and mouths.

The sea lamprey is good at killing lake trout and other bony fish because it has a disc-shaped, suction-cup mouth with sharp, sticky teeth that it uses to grab and hold on to the fish. The lamprey’s rough mouth then scrapes off the fish’s flesh, letting it feed on the blood and other bodily fluids of its host. One lamprey fish eats about 40 pounds of food every year.

Basic External Anatomy of the Parasitic Lamprey

Sea lampreys got into the Great Lakes through the Welland Canal in the 1830s. This canal joins Lakes Ontario and Erie and is a key part of the St. Lawrence Seaway. In just ten years, they were able to get into all five of the Great Lakes and started eating fish that were valuable for business, like trout, whitefish, perch, and sturgeon. The lamprey’s uncontrolled growth was a big reason why the trout fishery ended within a hundred years.

The Great Lakes Fishery Commission now makes sure that the US Fish and Wildlife Service and Fisheries and Oceans Canada do their jobs to control sea lamprey in the lakes. Field scientists put up barriers and traps in the streams that feed the lakes to stop lamprey larvae from moving upstream. They also use lampricides, which kill only lamprey larvae and don’t hurt other aquatic life.

Sea lampreys cling to and feed on a brown trout


People are always coming up with new ways to control sea lampreys. Scientists have made copies of the smells that sea lampreys use to communicate (called pheromones) so that present control methods work better.

Northern Brook Lamprey Mouth

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