Rusty Crayfish (Orconectes rusticus)
Rusty crayfish 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, rusy 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. Femails 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 help detecting and reporting new infestations is vital to preventing their spread.
Identify Rusty Crayfish
General Characteristics
- Adults generally are 3-5 inches (7-13 cm) long
- 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 aquatic plants and animals from boat, motor, and trailer
- Drain lake or river water from livewell and bilge before leaving access
- Dispose of unwanted live bait and study specimens in the trash
- Never dump live fish or crayfish from one body of water into another
- Report new sightings - record exact location; store specimens in rubbing alcohol; if in Minnesota, call the MN Department of Natural Resources Invasive Species Program in St. Paul, 1-888-MINNDNR, or Doug Jensen of Minnesota Sea Grant.
Know the rules!
Specimens are needed to confirm sightings, but some jurisdictions prohibit or discourage possession and transport of rusty crayfish and other invasive aquatic plants and animals. Contact your local natural resource management agency for instructions. Unauthorized introduction of plants or fish into the wild is illegal. Protect your property and our waters.
Doug Jensen
