Colorado Parks and Wildlife announced the discovery of an invasive crayfish species in Lake Granby. The rusty crayfish, named for reddish spots on its shell, hasn’t been seen in the state in over a decade. The agency is on high alert because of Lake Granby’s proximity to the Colorado River, and is now focused on stopping the crayfish from spreading further. … Walters said the invaders eat small fish, insects and fish eggs, which disrupts the aquatic food web. They can also eat plants on the bottom of the reservoir, which serve as critical habitat for fish spawning and food for native wildlife.