Probably caused by some dickhead trying to use them as bait or something. Archive: https://archive.today/yWg6R From the post: >>Rusty crayfish, an aquatic nuisance and an invasive species, has been discovered in a Larimer County river south of Estes Park, according to Colorado Parks and Wildlife. This is the first time the crayfish has been confirmed in the agency’s northeast region and the second time it’s been found east of the Continental Divide in Colorado, state officials said in a news release. Wildlife officials said the crayfish was reported on April 7 in Larimer County’s West Fork Little Thompson River by a user on iNaturalist, a species identification app. A team from Colorado Parks and Wildlife was able to confirm the aquatic nuisance’s presence with genetic testing later that month, according to the agency’s news release. The rusty crayfish is native to the Ohio River basin and is one of Colorado wildlife managers’ top invasive concerns in the state. It is larger and more aggressive than Colorado’s native crayfish species, often outcompeting them for food and resources, state wildlife officials said.