Rusty crayfish (Orconectes rusticus) is a non-native invasive species that may have been intentionally introduced from a bait bucket release, a mercy release, or from an unintentional release such as a boat transfer. Rusty crayfish are commonly found in lakes, rivers, ponds and streams with clay, silt and gravel bottoms that contain rocks, logs or debris.
Rusty crayfish are prolific spawners, and can reduce lake and stream vegetation, depriving native fish of cover, spawning habitat and food. Female crayfish have the ability to carry fertilized eggs under their tail; this feature has allowed them to spread rapidly. They also reduce native crayfish populations.
Rusty crayfish are native to streams in Ohio (United States) and were introduced to the Great Lakes region of Canada by anglers who use them for bait. They have spread west via inter-connecting waterways and bait bucket transfers. Past experience in other North America watersheds indicate that once rusty crayfish are established they can not be eradicated. The best method of control is reducing the risk of accidental introduction from one waterbody to another.
Rusty crayfish can be identified by their larger size—adults can reach 7.5 to 13 cm from rostrum (part of shell in front of eyes) to tail, brown body and rusty colored patches on each side and claws with black bands near tips.