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Steamboat Springs — Local wildlife experts are keeping a wary eye on a new species of crayfish that was found in the Yampa River last year and plan to remove the invasive species once spring arrives.

Several rusty crayfish were found in the Yampa River and Catamount Reservoir last year, and because the species is more aggressive than other crayfish in the region, Colorado Division of Wildlife aquatic biologists said the crayfish might pose a risk to the health of other species.

“This is, right now, the only location in the western states where they’ve turned up,” said aquatic biologist Bill Atkinson.

There are no native species of crayfish in the region, but several other types of crayfish have been introduced in the past. The most common way for species to be introduced is by fishers who use the crayfish as bait and throw into the water the crayfish they did not use, or by people who stock private waterways with the crayfish as food for sport fish.

“This is another example of how we have created problems for our native species (by) people moving things around,” Colorado Division of Wildlife area wildlife manager Jim Haskins said.

The crayfish get to be about 4 inches long. So far, only four of the rusty crayfish were found in the Yampa River, downriver of the Catamount Reservoir, Atkinson said, but DOW workers will start trapping the crayfish in Lake Catamount in April and in the river after the high water mark in June.

“We’re looking to get on top of it before the population in the river takes hold,” he said.

There are several possible threats from the rusty crayfish, including the possibility that they become effective predators that displace species already in the river.

“If, say, they were to respond to the environmental conditions in the Yampa River better than the existing crayfish species … they may increase,” Atkinson said.

That may alter the health of other species in the river as those species compete for limited resources, he said, although the final impacts are not yet clear.

“There’s a lot we don’t know,” Atkinson said.

— To reach Zach Fridell, call 871-4208 or e-mail zfridell@steamboatpilot.com