The rusty is certainly built for takeover. If you go into a stream and as you are walking you see crayfish move, you’re walking in a stream that has been invaded by rusty crayfish.”

In the mainstem of the Susquehanna, Pennsylvania’s largest river, the rusty has completely booted out native crayfish that provide food for a variety of land and underwater predators, as well as creating tunnels that are needed by insects for habitat.Īdded Kilian, “They are so good at overtaking native crayfish because they can just swamp a system. In Maryland, which has nine native species of crayfish, the rusty is now the second-most prevalent crayfish, second only to virile crayfish, another invasive crayfish. In addition, most states have banned the sale and possession of rusty crayfish. That translates into educating the public about the problem with the aim of preventing new waterways from becoming infested. So fishery agencies have been forced to adopt a stop-the-spread fight. The focus is on preventing them from getting there,” said Jay Kilian, a biologist with the Maryland Department of Natural Resources. “Across the board, the idea is once they’re in, you’ve lost the battle. The use of chemicals would destroy any remaining native crayfish. The crayfish is only native to parts of Ohio, Kentucky and Indiana in the Ohio River drainage.įrustrating fishery managers, there is apparently no way to beat back the hordes. It has not been found in the portion of Delaware that drains into the Bay.įish species have declined in many spots in Midwest states where the invasion began about 20 years earlier, as the crayfish consume fish eggs and destroy habitat. Both the Susquehanna and Potomac rivers have major infestations. The rusty crayfish has been found in Maryland since 2007, Virginia since 2011, Pennsylvania since 1976, West Virginia since 1977, and New York since 1978. The presence of these large, abnormally aggressive crayfish with large pincers and an indiscriminating appetite continues to expand, crowding out native crayfish and destroying underwater vegetation. But the rusty crayfish has also reached the Bay watershed by way of aquarium lovers, aquaculture and even school classrooms. It has been introduced mainly by anglers who use the rusty crayfish for bait and dump extras into streams. No matter what you call the crustaceans, the rusty crayfish, an interloper from the Ohio River watershed, has become one of the most destructive invasive species in the streams and rivers of Chesapeake Bay states.

Rusty crayfish