Steamboat Springs The invasion of rusty crayfish in the Yampa River has led the Division of Wildlife to issue an order that prohibits taking live crawfish from the Yampa and its tributaries.
Rusty crayfish, a nonnative species that biologists say are more aggressive than native crawfish, were found at several sites along the Yampa River last year and early this year.
The new regulation from the DOW went into effect Friday and prohibits any taking of live crawfish from any of the rivers or lakes that fall in the Yampa River basin that extends across almost all of Routt County.
Rusty crayfish are hard to distinguish from native species, so all crawfish taken from the waterways must either be immediately returned where they were found or killed by separating the tail from the body, the new regulation states.
Anglers often use the crawfish as live bait, and people who eat crawfish often keep them alive before eating them, but that is no longer allowed.
DOW state invasive species coordinator Elizabeth Brown said no crawfish are native to the Western Slope, but this species causes more problems than most.
“This is a particularly invasive species for a number of different reasons, mostly ecological reasons,” she said. “They’re highly aggressive with fish, they reproduce more rapidly, they outcompete the other species (and) they chew down the weed beds.”
One study shows that the rusty crayfish can eat up to twice as much as similarly sized northern crayfish, mostly eating fish, fish eggs, invertebrates and aquatic plants, according to the DOW.
Rusty crayfish were found in three locations on the Yampa River, all south of Steamboat Springs, Brown said.
Brown said as the rusty crayfish eat the weed beds, they also fragment the weeds, causing them to spread to areas.
“They just change the dynamics of the system,” she said. “When something is not supposed to be there and you introduce it, over time, it just changes the system,” and some species are more detrimental than others.
The ban is in effect until Dec. 31, and Brown said a more long-term solution, likely continuing the ban, will be crafted this year.