Is that an alien!? (The guide to whether you’ve found a sea lamprey or not.)

So, say you’re fishing in one of the waterways of Ohio. Perhaps you’re angling in Lake Erie itself! You feel a tug on your line, and reel it in. But… what’s this? On the side of the otherwise large and pristine-looking fish is a large, long eel-like thing.

It’s just hanging there, attached by what seems to be its mouth. We’ve said it before in blog posts about sea lampreys, but it does look alien! We know by now, though, that it’s just one of the invasive species that has made Lake Erie its home — the sea lamprey.

In this case, since the fish in question is actually hanging off of the side of the fish you were trying to catch, it’s pretty obvious that we have found a sea lamprey. After all, they do look very distinctive, don’t they? Well, believe it or not, there are some other fish in the area who can be mistaken for the dreaded sea lamprey. There are, according to the Ohio Department of Natural Resources, six native lamprey species in the state. (Including one, which is endangered, that is actually called the Ohio Lamprey.)  Seven all together are found here, including the sea lamprey.

And it’s not just sea lampreys that are easy to misidentify. Rich Carter, of the ODNR, reports that there are other invasives in Ohio that look similar to their native counterparts.

“We get reports on, on that site of other potential fish that turn out to be native if you will,” Carter says. “But a lot of times we get a reports of snakehead, which is another invasive fish that we are very concerned about. We’ve not seen any in the state of Ohio they’re over on the east coast, but we get reports from from anglers and… to date, it always turns out to be a native fish, which is called a bowfin, and the bowfin and the snakehead are very similar in their appearance.”

So when you find an invasive species and report it to an organization such as the ODNR, (Carter says this does help inform where the species are popping up) how are you to know if the fish you’ve found is a sea lamprey or something more innocent? Check out the handy guide below for more help.


Is this a sea lamprey? A helpful chart informed by the Ohio Department of Natural Resources Website

Parasitic native lamprey  (Ohio Lamprey)

  • The native lamprey, like the sea lamprey, has a long, eel-like body.
  • The native Ohio lamprey is parasitic, but rarely kills its host fish.
  • 53-62 muscle segments, known as “myomeres” on the body.
  • Can reach up to 15 inches in length.
  • Adults are “light tan or silvery tan” in color, and turn blue-black in coloration during spawning.
  • Two dorsal fins.
  • Endangered.


Sea lamprey (Invasive to Ohio)

  • Like the native lamprey, the sea lamprey has a long body.
  • The sea lamprey is parasitic, and often destroys its host fish.
  • 63-80 muscle segments, known as “myomeres” on the body.
  • Can reach up to 25 inches in length.
  • Adults are “dark tan above and lighter below with many darker speckles or blotches,” and turn blue-black during spawning.
  • Two distinct dorsal fins.
  • Invasive.


Non-parasitic native lamprey (American Brook Lamprey)

  • This native lamprey also has a long, eel-like body, though it is shorter than the sea lamprey and other native lampreys.
  • This lamprey is not parasitic.
  • 63-73 muscle segments, known as “myomeres” on the body.
  • Can reach up to 8 inches in length.
  • Adults are “dark tan above and lighter below” and turn  blue-black during spawning.
  • Two distinct dorsal fins.
  • Native.

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