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A crayfish with brown and white splotches and narrow claws with deep red tips
Information icon Slenderclaw crayfish (Cambarus cracens). Photo © Guenter Schuster.

Slenderclaw crayfish

Cambarus cracens

The slenderclaw crayfish is a relatively small freshwater crustacean that is endemic to streams within the Tennessee River Basin in DeKalb and Marshall counties, Alabama. The U.S. Fish and Wildlife Service is proposing to list the slenderclaw crayfish as a threatened species throughout its range with a 4(d) rule. We also intend to propose designation of critical habitat.

Download the Species Status Assessment (SSA).


The slenderclaw crayfish is a relatively small crayfish, ranging from 1 to 1 ½ inches in size. The colors range from olive green to rusty brown.

A crayfish on a black background with one red-tipped claw noticibly larger than the other
Slenderclaw crayfish, dead specimen. Photo © Guenter A. Schuster, Department of Biological Sciences, Eastern Kentucky University.


The crayfish occurs in small to medium flowing streams with intact native vegetation on the stream banks and boulder and cobble substrates. In addition, the species needs abundant space within each habitat type for sheltering and adequate seasonal water flows to maintain connectivity of streams.


Based on the best available information from other crayfishes, slenderclaw crayfish likely eat aquatic macroinvertebrates in the juvenile stage and shift toward eating both plant and animals in the adult stage.

Historical range

The historical range of the slenderclaw crayfish included four small streams or tributaries within the two watersheds. Historically, it was known to be in five sites: one site in Short Creek, one site in Shoal Creek, two sites in Scarham Creek and one in Bengis Creek.

Current range

Currently, the slenderclaw crayfish is in five sites within two populations: Shoal Creek and Town Creek watersheds. The site on Short Creek is now occupied by the non-native virile crayfish, which has been identified as the primary future threat to the slenderclaw crayfish.

Conservation challenges

A map of northeastern Alabama showing streams critical to the survival of the slenderclaw crayfish
Documented presence of virile crayfish within the historical range and surrounding area of slenderclaw crayfish during 2009 – 2017. Black crosses are locations where virile crayfish were collected. Short Creek population is highlighted in blue; the Town Creek population is highlighted in yellow. Map by USFWS.

Non-native virile crayfish, low abundance, and water quality put the slenderclaw crayfish at risk of being in danger of extinction within the next 10 to 20 years. The invasive virile crayfish is the biggest threat against the species. It has been documented to occur in Guntersville Lake (a Tennessee Valley Authority reservoir constructed in 1939 on the Tennessee River mainstem). During our analysis, the Service estimated that once virile crayfish reaches a known slenderclaw crayfish site, the slenderclaw crayfish would be eliminated within 10 years.

Recovery plan

A recovery plan has not been developed at this time.

Partnerships, research and projects

There are currently multiple programs in place to help improve the stream habitat of the slenderclaw crayfish, including the Natural Resources Conservation Service’s National Water Quality Initiative, Total Maximum Daily Loads in Scarham and Town Creeks to limit pollutants in the water, and the Farm Service Agency’s Conservation Reserve Program.

The Service will partner with these groups to help conserve the slenderclaw crayfish and its habitat.

How you can help

  • Do not release any non-native species into the water. If live fishing bait is used from another location, do not release it into the water.
  • Don’t dump chemicals into streams, and do report spills to state environmental protection agencies. During projects that disturb the ground, use best management practices to keep the sediment out of the streams.
  • Plant trees and other native woody vegetation along stream banks to help restore and preserve water quality.
  • Conserve water to allow more water to remain in streams.
  • Use pesticides responsibly (especially around streams and lakes) to prevent runoff.
  • Help your family find ways to reduce the amount of chemicals that you pour down the drain in your home or use on your lawn or garden.
  • Support conservation efforts that protect these unique animals and the habitats they live in.
  • Support local and state initiatives for watershed and water quality protection and improvement.

Subject matter experts

Designated Critical Habitat

A map of northeastern Alabama showing streams critical to the survival of the slenderclaw crayfish
Critical habitat map for slenderclaw crayfish. Map by USFWS.

The proposed critical habitat designation for the slenderclaw crayfish consists of 52 river miles of occupied habitat and 26 river miles of unoccupied habitat, totaling 78 river miles. The two proposed units are privately owned except for the bridge crossings and road easements which are publicly owned by the state and counties.

Unit 1 includes stream habitat in Bengis and Town Creeks. Unit 2 includes stream habitat in Shoal, Scarham and Short Creeks.

Establishing critical habitat will raise awareness of the needs of the slenderclaw crayfish and other imperiled species, and focus the efforts of our conservation partners. It also alerts federal agencies that they are required to make special conservation efforts when they work, fund or permit activities in those areas. It does not set up a preserve or refuge, but may require special management considerations in the identified areas. Designating critical habitat under the ESA does not affect private landowners unless the action involves federal funds, permits, or other federally activities. The final decision to designate critical habitat will be based on the best scientific information available.

Federal Register notices

The following Federal Register documents were automatically gathered by searching the Federal Register Official API with this species’ scientific name ordered by relevance. You can conduct your own search on the Federal Register website.

  • We're sorry but an error occurred. Visit the Federal Register to conduct your own search.

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