Wildlife Watch: The science behind eradicating sea lamprey

Published: Oct. 1, 2019 at 2:27 PM EDT
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Species of fish that have been part of the Lake Champlain basin ecosystem for thousands of year are being threatened by the sea lamprey, but experts say efforts to eradicate the parasitic fish are paying off.

New York wildlife officials say a single sea lamprey can kill as much as 40 pounds of fish during its lifetime. Our Ike Bendavid spoke with Bradley Young with the U.S. Fish and Wildlife Service to find out these efforts are considered so important.

Yellow water is noticeable at the Lewis Creek Falls in Ferrisburgh. The lampricide chemical is carefully monitored by crews to kill parasitic sea lamprey that infest the waters in our region.

Reporter Ike Bendavid: What is a sea lamprey?

Bradley Young: Sea lamprey is a parasitic fish that lives in Lake Champlain. It's a parasite and its life cycle is such that it grows for four years in the rivers and it migrates out to the lake where it spends a year and a half as a parasite attached to host species, mostly lake trout, salmon but also lake sturgeon, walleye bass as well. Once it becomes large enough it comes back in to complete its life cycle as an adult and spawns and starts all over again

Reporter Ike Bendavid: You called it a parasite. Should I ever be concerned if I am in a creek or in lake Champlain?

Bradley Young: In the rivers and creeks you will never see a parasitic sea lamprey. They do live in there, they spawn in there and the young larva grow in there; however, they are not in their parasitic form while they are in the rivers. The only time the lamprey are parasitic is while they are in Lake Champlain and at that time if you are on the beach or somewhere nearby, you are not going to see a parasitic sea lamprey. They are out in the deepest, coldest part of the lake, feeding on hosts out in that area.

It's unclear where the lamprey come from . Young says there is debate whether they are native or invasive. "It's really not known for sure. There is some genetic evidence that suggests that they have been here since the last glaciation event. But actually the other information we have shows us that demographically they haven't been recorded till about 1922," Young said.

Federal and state crews take samples on lake shores and in their mobile command center, testing the concentration of the chemical they're putting in the water..

"Today we are applying a chemical to the river. It's called a lampricide and it's an aquatic pesticide. The nice thing about it is that it's unlike most pesticides which are considered broad spectrum, meaning they kill about everything they come in contact with. This is a selective lampricide and it only kills sea lamprey. It has some effect on other species to varying degrees but it's specific for sea lamprey. And that's because sea lamprey are a very primitive organism evolutionarily. They haven't developed the same physiology as other fish so they can't detoxify and can't process the chemical the way other fish like a bass or a minnow or a trout can. So the chemical builds up in their body, they can't process it, it's toxic and it kills them, whereas other organisms in the river are able to process that and survive just fine.

Reporter Ike Bendavid: This isn't affecting any other wildlife?

Bradley Young: It affects them. We definitely have other organisms -- some salamanders are sensitive to it, some fish species are sensitive -- but as long as we are very careful with the concentration that we use, we can apply it and monitor it and meter it very carefully so that the concentration doesn't get high enough to kill the other organisms but it is high enough to kill sea lamprey.

Reporter Ike Bendavid: You can literally see the chemical right here. Why are you putting it at the end of a waterfall?

Bradley Young: At the end of the waterfall the flow coming down -- it's a big churning effect going on, so it's like a giant mixer for us. It's very important for us to get the chemical mixed as soon as possible.

Reporter Ike Bendavid: How are you monitoring it?

Bradley Young: We put the chemical in at our application point with medical grade pumps. These are the ones used for chemotherapy so they are very high tech, very high grade. The amount we put in is very closely measured and monitored. Then we have a laboratory downstream where we are monitoring and measuring the concentration in the river every half hour. And depending on what the concentration on what the river reads, we send back the information to the application point to increase or decrease the amount of chemical to make sure we are maintaining the right amount of concentration.

Reporter Ike Bendavid: When does this chemical wear off?

Bradley Young: So the chemical is being applied for 12 hours. We started at 6 a.m. and will go to 6 p.m. and it more or less just follows the flow of the river. So the river will flush itself out and go to the lake. It naturally breaks down through photolysis, meaning that sunlight breaks it down. And after a day or two, even in the lake, just natural sunlight breaks the bonds of the chemical. It's still there in different forms but the molecular structure that's toxic becomes non-toxic and it dissipates to a concentration that's no longer detectable.

Each river that flows into Lake Champlain gets treated every four years. Fish and Wildlife wants the people who use Vermont's waterways to know there's science behind what they're doing. "We don't do this willy-nilly. We don't dump chemicals. A lot of time we get offended when we hear the word 'dump chemicals.' There is nothing dumping about this. As you can see with our pumps, this is extremely carefully monitored and measured. The amount of science behind this is tremendous," Young said.

Today's treatment, if done properly, could result in the death of tens of thousands of lamprey. Lamprey that will never become parasites in Lake Champlain.