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Michigan DNR trying new approaches against invasive crayfish

Closeup of a hand holding a large, red crayfish with red bumps on its pincers.
Matthew Clara
Michigan Department of Natural Resources
Michigan Department of Natural Resources technicians collect red swamp crayfish from a retention pond in Novi in August 2022.

State researchers are exploring new techniques to remove an invasive crayfish from Michigan waters.

The Michigan Department of Natural Resources has been fighting an invasion of red swamp crayfish since they first appeared in the state in 2017. Aggressive attempts to trap and remove the crustacean haven’t worked.

Kathleen Quebedeaux, a fisheries biologist with the DNR, said eradicating the invader will require a variety of approaches.

“In order to have a more efficient means of achieving eradication, we need other tools in our toolbox,” she said. Those tools include pesticide treatments, introducing predatory fish and adding lights to traps.

The DNR has partnered with several agencies and organizations to maximize research and funding. New possible solutions to the crayfish problem come from the U.S. Geological Survey, Michigan State University, Auburn University and the Wisconsin Department of Natural Resources.

One tool that's not new: trying to increase public awareness.

“The initial introduction of these crayfish everywhere is tied to people,” she said. “So, if people are aware of the issue, we can stop the introduction in the first place.”

Possession of live red swamp crayfish is illegal in Michigan, but their popularity as teaching aids, aquarium pets and casual seafood fare means they still find their way north.

People have also been instrumental in minimizing its spread. Most early detections of the crayfish have come from the public, Quebedeaux said. Identification materials are available through Michigan State University Extension.

There are about 600 species of crayfish worldwide, over half of which reside in North America. The red swamp crayfish, a native of the Gulf Coast, threatens the eight species native to Michigan. The invader outcompetes native species for food, reproduces quickly and preys on less dominant crayfish.

“They’ll eat anything they can get their hands on,” Quebedeaux said. The crustacean also disturbs water quality and bank stability with its aggressive burrowing.

The invasive population is mostly confined to the Metro Detroit area, with a couple exceptions in Howell and west Michigan. It isn’t widespread — yet.

“That's part of why we've had such an aggressive response,” she said. “We believe that the invasion is still early enough in the process... that we believe eradication is possible.”

Elinor Epperson is an environment intern through the Great Lakes News Collaborative. She is wrapping up her master's degree in journalism at Michigan State University.