The Iowa Department of Natural Resources (DNR) is announcing restrictions on crayfish harvesting at Storm Lake in an effort to help reduce the spread of rusty crayfish to other waterbodies. Licensed bait dealers can no longer harvest any species from Storm Lake. Those collected for personal use may still be used, but only in Storm Lake. Rusty crayfish are listed as a prohibited aquatic invasive species in Iowa and they are spreading to lakes, rivers and streams in the Midwest. The DNR believes this is most likely happening in a combination of ways: when anglers release them from bait buckets, hobbyists dump them out of aquariums and from commercial harvesting activities. This is a more aggressive form of crayfish and can displace the native species, harm the fish population by eating their eggs and young and can graze and eliminate aquatic plant life. The Storm Lake infestation was confirmed earlier this year, but prior to that, the key locations identified with an abundance of rusty crayfish were mainly found in sections of Maquoketa and the Middle Iowa, Upper Cedar and Upper Wapsipinicon rivers in eastern Iowa.