What are rusty crayfish? ‘Aggressive’ invasive species has been found in Kansas lake

An invasive species known to attack the feet of unsuspecting swimmers was just discovered in a Kansas lake, officials said.

The Kansas Department of Wildlife and Parks found rusty crayfish in McPherson State Fishing Lake, an invasive species never before documented living in the wild in the state.

Researchers captured male and female crayfish of various ages, a sign an established population is thriving.

“The most likely cause of the rusty crayfish making its way into Kansas is through its use as fishing bait,” Kansas Department of Wildlife and Parks Aquatic Nuisance Species coordinator Chris Steffen said in a news release.

This species is regarded as a “large, aggressive crayfish” that’s “known to attack the feet of unsuspecting humans and animals standing in freshwater.” It also beats out native fish and crayfish for forage used by certain predator species for cover, officials said.

Rusty crayfish have “large, black-tipped claws” and rust-colored spots on their upper shell. The species is native to the Ohio River drainage basin and first was discovered outside its native range in Wisconsin in the 1960s, according to the U.S. Department of Agriculture.


Now rusty crayfish are found most frequently in the Great Lakes region, New England and the eastern U.S., officials said.

“This species is a prime example of the importance of always draining water from your boat, livewell, and bilge before leaving a waterbody, and of never moving bait from one waterbody to another,” Steffen said. “You just never know what could be hitchhiking a ride.”

The McPherson State Fishing Lake in south central Kansas is among several small bodies of water that will be inspected to determine whether long-term monitoring of native and invasive crayfish is necessary.


“To the surprise of staff and researchers, the need for such protocols would be validated almost as quickly as the research project began,” the news release said.

The Kansas Department of Wildlife and Parks asked anyone who spots a rusty crayfish to freeze them and note the date and location of the capture to report to the agency.

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