Rusty Crayfish – Oneida County Aquatic Invasive Species Program

Identification: Tan brown body with rusty-colored spots on both sides of the carapace. They have robust claws with black bands on the tips. They reach a maximum of 10 cm long.

Ecology and Natural History: Rusty crayfish are native to the Ohio River basin. They species was introduced by being used as fish bait. They are also commonly sold to schools for biology classes. Rusty crayfish inhabit lakes, ponds, and streams. They must have well-oxygenated water to survive. Females lay between 80 to 575 eggs! Adult males molt their exoskeleton twice per year while females molt once per year. They can live up to five years. Rusty crayfish are opportunistic consumers that feed on plants, invertebrates, detritus, algae, fish eggs, and small fish.

Impact of Introduction: Native crayfish are at risk of being displaced because rusty crayfish are more aggressive. They have the ability to cause a reduction in many native fish populations. Rusty are also more likely to compete with juvenile game fish for food than are native crayfish. They also serve as lower quality food due to the low ratio of soft tissue to hard exoskeleton.

Oneida County Waterbodies with Rusty Crayfish: Bearskin Creek, Bearskin Lake, Big Carr Lake, Big Fork Lake, Big Lake, Big Stone Lake, Birch Lake, Booth Lake, Bridge Lake, Carrol Lake, Chain Lake, Cranberry Lake, Crescent Creek, Crescent Lake, Crystal Lake, Dam Lake, Deer Lake, Dog Lake, Echo Lake, Fourmile Lake, Fourth Lake, George Lake, Green Bass Lake, Hancock Lake, Hasbrook Lake, Island Lake, Julia Lake, Kaubashine Creek, Kawaguesaga Lake, Lake Nokomis, Lake Thompson, Laurel Lake, Little Bearskin Lake, Little Fork Lake, Little Tomahawk Lake, Long Lake, Lower Kaubashine Lake, Mercer Lake, Mid Lake, Minocqua Lake, Minocqua Thoroughfare, Moen Lake, Oneida Lake, Pelican Lake, Planting Ground Lake, Rainbow Flowage, Range Line Lake, Rhinelander Flowage, Rive River Flowage, Round Lake, Sand Lake, Scott Creek, Sevenmile Lake, Squash Lake, Squaw Lake, Squirrel Lake, Squirrel River, Stone Lake, Tomahawk Lake, Tomahawk River, Tomahawk Thoroughfare, Townline Lake, Two Sisters Lake, Upper Kaubashine Lake, Upper Post Lake, Venus Lake, Virgin Lake, Whitefish Lake, Willow Flowage, Willow Lake, and the Willow River.