WUOMFM

Sex, death and sea lampreys

Aug 13, 2015

Sea lampreys attach themselves to a fish with this mouth in order to consume the fish's blood and body fluids.
Credit Flickr user PROUSFWSmidwest / Flickr

Each invasive sea lamprey can kill 40 pounds of fish a year in the Great Lakes.

We spend more than $28 million in federal money each year to control the lampreys (according to the Great Lakes Fishery Commission, $20.9 million goes to sea lamprey control measures and more than $3 million is spent on sea lamprey research).

Michael Wagner is an associate professor in the Department of Fisheries and Wildlife at Michigan State University.

He’s one of the researchers at MSU testing out ways to attract sea lampreys into traps.

“There’s an interesting pest management technique that’s been attempted with insects in the past called push-pull,” Wagner says.

Wagner says they used a repellant that lampreys release when they’re attacked, and a lamprey sex pheromone to try to attract them at the same time. They did these experiments in a river near Mackinac City, for their study recently published in the Canadian Journal of Fisheries and Aquatic Sciences.

“And the idea is if you can combine cues that sort of act in opposition to each other, you can more effectively guide animals into the area you want them to be,” Wagner says.

“If we understand how they use combinations of pheromones and alarm cues in environmental circumstances to make decisions about which stream to spawn in or what area of the river to move through, that’s where we can then more effectively target the placement of traps or the treatment — the application of pesticide — to remove subsequent reproduction,” he says.

And the repellant worked – lampreys went into the trap twice as fast as they would’ve otherwise, Wagner says. But in this study, the lampreys were not lured in any faster by the sex pheromone.

Sea lamprey wounds.
Credit Flickr user USFWSmidwest / Flickr

Wagner says they’re hoping the repellant and the pheromones can eventually be additional tools to control sea lampreys.

“I think the end game here, for this work, is not eradication of the species from the environment,” he says. “This is a large population in an open ecosystem and that type of thing just generally is not achievable with the level of technology that we have available to us now.”

But he says the goal is to more effectively target sea lamprey control efforts.

“In other words, we can kill the same number of animals without increasing things like the amount of pesticide that we release into the environment.”

Right now, sea lampreys are mainly controlled with a lampricide called TFM.

As the Great Lakes Fishery Commission explains on its website:

The primary method to control sea lampreys is the application of the lampricide TFM to target sea lamprey larvae in their nursery tributaries. In the concentrations used, TFM kills larvae before they develop lethal mouths and migrate to the lakes to feed on fish, while most other organisms are unaffected by TFM.