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Lamprey control aims at eradicating them in the larva stage (in hand) before they grow into toothy adults (inset) Photo: Sarah Harris
Lamprey control aims at eradicating them in the larva stage (in hand) before they grow into toothy adults (inset) Photo: Sarah Harris

Natural Selections: Lampreys

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Lampreys - are they fish or eel? Martha Foley and Dr. Curt Stager talk about this jawless fish with a head full of teeth and a sucking mouth.

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Martha Foley: We usually hear about lampreys when someone’s trying to eliminate them because they’re seen as a parasite on trout, salmon, at least in Lake Champlain where we are. Are they fish or eel?

Dr. Curt Stager: Well, lampreys are fish, but they’re not what you think of a normal fish maybe. Like for example an eel looks like a snake, but it really is what you call a normal fish because it’s got kind of normal looking gill slits. It's got jaws that’ll open and close like a fish would. It's got paired fins in the front, like we’ve got front limbs. And it’s got a skeleton made out of bone and stuff. Lampreys are different. They look like an eel, but there are some really major differences that date back to the early days of fish evolution.

MF: So they’re kind of an early kind of fish, would you say?

CS: They’re kind of like copies of an early version of fish. The skeleton is there but it’s not made out of bone, it’s made out of cartilage, just the stuff that stiffens your nose and ears and stuff. So it looks like bones, but it’s not. They don’t have jaws. So instead of—

MF: They have a lot of teeth.

CS: They’ve got a mouth and they’ve got teeth, but they’re not stuck on jaws, they’ve got a big sucker-disc with hook teeth on it to hang on, and a tongue that’s kind of raspy like a file to kind of rasp into the side of a prey fish.

MF: Well that’s what we know about them, that sucker-hole and how they suck the life out of the fish that they’re on, right?

CS: Yeah, it’s kind of gross in a lot of ways. A lot of people are kind of horrified when they see that, but if you start looking at other aspects of them, they’re really fascinating. Actually, one last thing about that sucker-disc is I always wondered “How do they hold on?” it’s this round thing with teeth on it, sure, but how do they do it. It turns out there’s a hole running from their forehead, or the top of their head kind of like a nostril, down into the sucker. So, they can make a suction to kind of pull the mouth onto the fish first and then of clamp shut and hold it on there kind of like a toilet plunger almost.

MF: I think that’s more creepy- even more creepy than I had thought.

CS: Yeah, but there are some other neat things about the sucker, 'cause they do other things with it. So, a lot of their life cycle is kind of like salmon, which we like hearing about how they swim up the river, make a nest, and spawn and die. The Lampreys do that too.

MF: You mean they go up those same rivers that the salmon go up.

CS: Which sort of makes sense cause a lot of times they’re parasitic on salmon and lake trout and stuff like that, so they can do this kind of thing. It turns out most of the years of their lives, which could be like 20 years, they’re living as these larvae that are blind, just filter feeders, and they live in the sediment and don’t both anybody.

But when they’re ready to breed, as adults, they come out totally transformed what they look like. Their organs change, they develop eyes, and they get a sucker-disc. And then they’ll latch onto a fish and be a parasite for a while, but to breed they go up the rivers just like salmon do. The males will then make a place to live in the gravel, a little nest, and they use their sucker to pick up stones and gravel and move it away and make a little depression.

MF: No kidding.

CS: And they’ll do it around a bigger boulder that sort of acts like this breeding platform. A gal shows up, and if she likes him and his nest, she’ll latch on with her sucker onto that big rock in the middle of the nest and start to lay her eggs in the nest.

MF: And then there he is—

CS: That’s where he is, and he’ll fertilize the eggs in the nest. So it’s kind of neat they use their sucker for all kinds of things, not just the nasty, creepy stuff.

MF: So, when we hear about lampricide being applied to waters where wildlife biologists are trying to eliminate lampreys, do all the lampreys get wiped out by that? Different kinds of lampreys? You say you didn't know there were so many.

CS: Well yeah that was my biggest surprise. I just sort of thought there was “The” Sea Lamprey or something, but there are 40 species, at least, in the world. And in Lake Champlain, near my home, where I hear about this problem a lot, there are four species in there.

MF: And they all get wiped out by the lampricide?

CS: They would all get wiped out by the lampricide. There are two species of brook lamprey that basically don’t act like parasites. So these other kinds of lampreys can be like collateral damage when you’re trying to get rid of the sea lampreys that you don’t want for fisheries management purposes.

And I was also surprised to find out that there are a lot of species of lampreys in the world. Some of them are rare and some of them are even unique to a specific river, and that means some of them are endangered. So ironically, in some watersheds, fisheries biologists are trying to get rid of Sea Lampreys, let's say, but in other watersheds they’re trying to protect the native Lampreys of other types.

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