Rusty Crayfish

Rusty crayfish are native to streams in Ohio, Kentucky, Illinois, Indiana, and Tennessee. They were probably introduced into Wisconsin waters by anglers who used them as live bait.

Rusty crayfish can usually be identified from our native species by their larger, more robust claws. The claws also have dark bands on the tips. They also display rusty spots on each side of their carapace. These spots are located on the body as though you picked up the crayfish with paint on your forefinger and thumb. The spots may not always be present or well developed on rusty crayfish from some waters.

Rusty crayfish are common in many of our county inland rivers and streams, as well as our neighboring counties. Rusty crayfish eat small fish, insects, and fish eggs. They are aggressive and can displace native crawfish and can reach higher densities. They also consume more food than our native crawfish, acting like little lawn mowers, destroying underwater habitat that is important for fish spawning, cover, and food. Rusty crayfish are prolific. The females lay from 80-575 eggs! To make it even worse, female crayfish actually store sperm until they are ready to release their eggs, so adding just one crawfish to a waterbody can start an infestation.

The rusty crayfish is not to be confused with the red swamp crayfish which was found in Germantown, WI in 2009. The red swamp crawfish are dark red with raised bright red spots covering the body and claws. They also pose a severe threat to our native lake and riverine ecosystems. For additional information on the red swamp crayfish, visit www.dnr.wi.gov/invasives/pdfs/redcrayfish.pdf

The damage and destruction these crawfish cause is the reason it is illegal to possess both live crayfish and angling equipment simultaneously on any inland Wisconsin water (except the Mississippi River). It is also illegal to release crayfish into a water of the state without a permit. A fishing license is required to harvest crayfish.

To prevent the spread of the rusty and red swamp crayfish, as well as other aquatic invasive species, never release any aquarium pets or plants in to the wild and always dispose of unwanted crayfish in the trash. Never release them alive.

Instead, catch them and cook them. For recipes, visit www.seagrant.umn.edu/fisheries/craving_for_crayfish
A free booklet "A Craving for Crayfish", with ten recipes can be ordered from www.seagrant.umn.edu/publications/c4