Rusty Crayfish

A rusty crayfish.


(The Center Square) — An invasive species of crayfish has been discovered in the Laramie River after being illegally introduced.

The rusty crayfish has been found near Tunnel Road and the Laramie Wildlife Habitat Management Area, according to Wyoming Game and Fish Department’s (WGFD) Laramie Region Fishery Supervisor Bobby Compton.

Although the first discovery of the invasive aquatic critters was made only in September, Compton said the crayfish were likely introduced between 15 and 20 years ago.

“They were likely brought in with other sport fish, which were stocked legally,” he told The Center Square.

A fish hatchery likely brought the crayfish in as they provide good forage for larger fish like trout, he said. 

“We think it was purposeful but we’ll never know,” Compton said.

The rusty crayfish is on Wyoming’s list of aquatic invasive species as well as several other states. The species is endemic to the Ohio River Basin.

“We’re still sampling and learning a lot about this,” he said.

The University of Wyoming found them during a survey of crayfish statewide to find out which species were present in different waters. Once notified, WGFD picked up the research. Compton said the department is still determining how far the unwelcome crustaceans have spread.

As a non-native species, the rusty crayfish poses serious problems to native aquatic fauna. 

“We know based on other states and literature that they’re really destructive and they could have lasting ecological consequences,” Compton said.

He pointed to the classic case of non-native animals often being better suited to the environment and, as a result, winning the competition for food and habitat with native species. Compton added there are native crayfish in Wyoming’s waters that could be threatened.

They can also be hard on aquatic vegetation with their digging habits, he said — vegetation that native animals rely on.

“They could also prey on fish eggs and small fish, too — so they could eat them as well,” Compton said.

It is illegal to possess an invasive aquatic species so if anyone finds one, they should report it to WGFD. Compton added it would be great if they took a photo for research purposes and then killed it, but understands not everyone has the heart to do that.