Yup, those were crawdad claws on Chicago beaches WBBM Newsradio 780 (12/22) Anybody walking along the lake near the Montrose Dog Beach a week ago could easily have seen dozens if not hundreds of crab claws in the sand. "I believe those are from a rusty crayfish, what has been an invasive species in the Great Lakes region," says George Parsons, director of fishes at the Shedd Aquarium.
Rusty not too trusty when it's in your lake South Bend Tribune (1/22) The rusty crayfish is native to the Ohio River Valley but it's raising havoc in the waters of the upper Midwest, where it's considered an invasive species.
Overview Rusty crayfish (Orconectes rusticus) dwell in areas where rocks, logs or other debris can be used as cover; they do not, however, dig burrows, as do other crayfish. Habitat requirements also include permanent lakes or streams that provide suitable water quality year round.
This invasive crustacean is native to the Ohio River basin and portions of the states of Ohio, Kentucky and Indiana. They have spread to areas outside of their native range and established reproducing populations in areas of all Great Lakes states and the province of Ontario. They have also spread to areas beyond the Great Lakes basin, including east to New England, west to Colorado, Wyoming, and Oregon, and south to North Carolina and Tennessee.
Rusty crayfish can be difficult to identify as they are easily confused with other, similar species found in the region. Distinguishing characteristics of the rusty crayfish are their large claws and brown-colored bodies. They also exhibit dark, rusty spots on each side of their carapace, as though picked up with paint on one's forefinger and thumb. The spots may not always be present or well developed on rusty crayfish from some waters. The rusty's claw is grayish-green to reddish-brown and is smooth, with black bands at the tips.
Environmental impact: Upon establishment, rusty crayfish cause a range of ecological impacts. These include displacing and/or hybridizing with native crayfish, decreasing the density and variety of invertebrates, and reducing the abundance and diversity of aquatic plants that native fish use for cover and food. Several characteristics of the rusty crayfish provide a competitive edge in the invasion process. They are non-discriminatory, opportunistic feeders, consuming aquatic vegetation, worms, snails, leeches, clams, insects, other crustaceans, detritus, fish eggs and small fish. Their high metabolic rate allows feeding at two times the level of similarly sized native crayfish. Also notable is their ability to reproduce without both sexes present. One female carrying viable sperm can begin a new population if released into a suitable environment.
Invasive Species Policy at the Regional Level: A multiple Weak Links Problem (2009) Fisheries, Volume 34, Issue 8 J.A. Peters and D.M. Lodge. This study examines the weaknesses in region-wide regulation of invasive species. Using the rusty crayfish as a model organism, the authors identified a continuum of inconsistent regulations throughout the Great Lakes region, hindering the successful prevention of rusty crayfish and other invasives throughout the basin.