Invasive Species: Sea Lamprey

By Evan Kreager
Great Lakes Echo
The sea lamprey, an eel-like creature that feeds on host-fish, has been named by The Nature Conservancy as one of the five "usual suspects" doing damage in the Great Lakes basin. (Image: The Nature Conservancy)

The sea lamprey, an eel-like creature that feeds on host-fish, has been named by The Nature Conservancy as one of the five “usual suspects” doing damage in the Great Lakes basin. (Image: The Nature Conservancy)

The Nature Conservancy has named sea lampreys one of the five “usual suspects” invading the Great Lakes basin.

These eel-looking parasites find a host and suck the life out of it. During the length of one life cycle, a sea lamprey can kill up to 40 pounds worth of fish and can grow up to 3 feet long.

Sea lampreys are native to the Atlantic Ocean, Lake Ontario and the St. Lawrence River. Though they are present throughout the Great Lakes region, control efforts have successfully reduced 90 percent of the sea lamprey population.

3 thoughts on “Invasive Species: Sea Lamprey

  1. A couple of links from this great site (; for more information on eels.

    http://greatlakesecho.org/2011/08/11/great-lakes-eels-are-a-conservation-challenge/

    http://greatlakesecho.org/2009/06/09/eels-edging-toward-extinction-in-lake-ontario/

    American eel
    “The fish lives most of its life in freshwater.

    Opportunistic feeders, it eats frogs, crayfish, insects, snails, earthworms, larval lamprey and fish like the invasive round goby.

    The eels then migrate to the Sargasso Sea – a section of the Atlantic Ocean near Bermuda where all American eels spawn. That’s more than 1500 miles from the mouth of the St. Lawrence River through which all Lake Ontario eels must pass.

    Young transparent eels, known as glass eels, then make their way back to rivers and streams along the Atlantic coast, including the St. Lawrence River.

    Unlike other migratory fish, they don’t have a homing signal, Taylor said. They come back to rivers and streams, where they mature, at random.

    But the number of eels returning to Lake Ontario and the St. Lawrence River has declined drastically.” more in the first link

  2. Hi Steve,

    The sea lamprey you see are actually native in your location. They return upriver to spawn every year and the larvae live embedded in sediments for many years before going out to sea. I have heard they make excellent fishing bait. We don’t yet have a good handle on how natural populations fluctuate, but they likely go through high and low years, which you may be seeing. Sea lamprey in their native range are important members of their ecosystem. Just because they don’t look pretty does not mean they don’t have important functions. For instance salmon find sea lamprey nests the best place to build their own, and parr feed on the invertebrates lamprey kick up while building their nests.

    The Great Lakes sea lamprey are destructive to native fishes and have been heavily controlled for >50 years now. They still pose a major threat to native fish, and without continuing control efforts few large fish would be left in the Lakes.

    Hope this helps!

  3. hi we ice fish here in the kennebacasis river(bay) in new brunswick and “lampers” have shown up( very small so far) again …wondering if they return on a cycle as they are not around every year and have been found in streams very far inland(chipman nb) in the past.discusting creatures..useless and make swimminng leary for some..would appreciate any answer…
    steve.mulberry@gmail.com..thanks

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