Rusty Crayfish (Orconectes rusticus)
Rusty crayfish (Orconectes rusticus) are invasive crustaceans spreading to lakes, rivers, and streams in several areas of North America. They are more aggressive than other native crayfish, better able to avoid fish predation, and can harm native fish populations by eating their eggs and young. They can displace native crayfish, hybridize with them, and graze on and eliminate aquatic plants.
Native to the Ohio River drainage, rusty crayfish have spread to several U.S. states and Ontario. They have likely spread through bait bucket release by anglers, aquarium release by hobbyists, activities of commercial harvesters, and live study specimen release by teachers and students who buy them from biological supply houses. Females can carry fertilized eggs or a male's sperm so even the release of a single female could establish a new population. Eradicating established infestations is impossible. Your actions and your help in reporting new infestations are vital for preventing their spread.
Identify Rusty Crayfish
- Adults generally 3-5 inches (7.5-13 cm) long (nose to tail)
- Claws larger and smoother than many other crayfish; usually without wart-like white bumps
- Claws with oval gap when closed; no distinct thin slit or notch present
What You Can Do
- Learn to identify rusty crayfish.
- Inspect and remove visible aquatic plants, animals, and mud from boat, motor, and trailer before transport.
- Drain lake or river water from bilge, livewell, and motor before leaving access.
- Dispose of unwanted live bait, worms, and study specimens in the trash.
- Rinse boat and equipment with high pressure, hot water, AND/OR
- Dry everything for five days or more before reuse.
- Never dump live fish or crayfish from one body of water into another.
- Report new sightings - note exact location; freeze specimen in a sealed plastic bag; and call the Minnesota Sea Grant Program in Duluth, (218) 726-8712; or a Minnesota DNR Invasive Species Specialist (see www.mndnr.gov/invasives/contacts.html), 1-888-MINNDNR or (651) 259-5100.
Know the rules!
Specimens are needed to confirm sightings, but some jurisdictions prohibit possession and transport of invasive aquatic plants and animals. Contact your local natural resource management agency for instructions. Unauthorized introduction of plants, fish, or invertebrates into the wild is illegal. Protect your property and our waters.
- Species Profile: Rusty Crayfish
- Rusty Crayfish: A Nasty Invader; Biology, Identification, and Impacts
- Craving for Crayfish: Minnesota Discovers a Louisiana Tradition
- Rusty Crayfish Images
- Invasive Crayfish Discovered in St. Louis Bay (Seiche, Sept. 1999)
- Publication: Rusty Crayfish WATCH Card
- Publication: Aquatic Invasive Species WATCH Cards (Full Deck)