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Little Tennessee Crayfish3 April 2008. Photo by Chris Skelton. Image may be subject to copyright.
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Cambarus georgiae Hobbs, 1981

Little Tennessee Crayfish

Federal Protection: No US federal protection

State Protection: Endangered

Global Rank: G2G3

State Rank: S1

SWAP High Priority Species (SGCN): Yes

Element Occurrences (EOs) in Georgia: 3

Habitat Summary for element in Georgia: Flowing or quieter areas of large streams to medium-sized rivers under rocks or in leaf packs


Description

The background color of the Little Tennessee Crayfish is greenish-gray and the animal appears somewhat mottled. The abdomen has paired, slanted dark marks down each side of center. The rostrum is fairly long, narrow, and pointed with marginal spines. The areola is wide and nearly parallel-sided and cervical spines are present. This species reaches a maximum total body length of about 63 mm (2.5 in).

Similar Species

The Common Crayfish (Cambarus bartonii) occurs with the Little Tennessee Crayfish and at a glance looks very similar. However, the Common Crayfish has a short, wide rostrum and lacks cervical spines.

Habitat

The Little Tennessee Crayfish is a stream dwelling species and can be found in leaf litter or other debris in moderately flowing water as well as under rocks in quieter parts of streams.

Diet

No studies of the Little Tennessee Crayfish are known. Crayfishes are considered opportunistic omnivores and are likely to feed on live and decaying vegetation, aquatic insect larvae, small fishes, and dead animal matter.

Life History

Stream dwelling crayfishes typically hide during the day and come out at night to feed. Reproduction usually occurs during the spring and fall, but males in reproductive condition may be found at any time during the year. When female crayfish are ready to lay eggs, they usually find a secure hiding place and hence are rarely encountered. When the eggs are released, the female attaches them to her swimmerets and is said to be “in berry.” Upon hatching, the juvenile crayfish are attached to the mother by a thread. After the juveniles molt for the second time, they are free of the mother, but stay close and will hold on to her for some time. Eventually they move off on their own. Crayfishes molt 6 or 7 times during their first year of life and most are probably able to reproduce by the end of that year. They molt once or twice a year for the remainder of their lives and live about 3 years. Very little is known concerning the life history of the Little Tennessee Crayfish. Males in reproductive condition have been collected in March, April, and May and a female carrying eggs was found in April. The smallest breeding male known is about 55 mm (2.2 in) and the female with eggs is about 50 mm (1.9 in) in length.

Survey Recommendations

Since this species is usually found in slow to moderately flowing water is it best to slowly remove rocks and coax the crayfish into a dipnet. Baited minnow traps set overnight may work as well.

Range

The Little Tennessee Crayfish is known primarily from the upper Little Tennessee River system in Macon County, North Carolina and Rabun County, Georgia. The Georgia range lies within the Blue Ridge physiographic province. In Georgia, the species appears to be restricted to the Little Tennessee River and Betty’s Creek.

Threats

The small range of this species increases the likelihood that it will be extirpated from Georgia. Agriculture in the Georgia section of the Little Tennessee River drainage is heavy and negatively impacting the watershed. Heavy algal growth (presumably caused by fertilizer runoff from fields) is present on rocks near the Georgia/North Carolina border and larger substrates are imbedded because of sedimentation. Imbedded substrates offer no daytime hiding places thus reducing available habitat. Residential and commercial growth in the region will likely increase the amount of impervious surface in the watershed which will lead to increased stormwater runoff. This runoff may contain toxins and increase stream temperatures which are harmful to all aquatic life. The introduction of non-native crayfishes is a threat to all native crayfishes.

Georgia Conservation Status

Much of the upper Little Tennessee River system in Georgia is surrounded by intensive agriculture and urban development and is in very poor condition. The population in Betty Creek (large Tennessee River tributary) is somewhat protected as the creek has excellent habitat quality and has a conservation easement in place in its headwaters.

Conservation Management Recommendations

Conserving populations of the Little Tennessee Crayfish will require general watershed level protection measures, including the protection of riparian zones, control of sediment and nutrient runoff from farms and construction sites, and limiting the amount of impervious cover (e.g., pavement) within occupied watersheds. Efforts should be made to work with landowers to implement best management practices for agriculture and to increase riparian buffers along the Little Tennessee River and its tributaries. Non-native crayfishes should never be used for bait. Instead, anglers should use crayfishes collected from the river system they will be fishing in and should never release unused bait crayfish back into Georgia waters.

References

Hobbs, H.H., Jr. 1981. The crayfishes of Georgia. Smithsonian Contributions to Zoology 318:1–549.

Hobbs, H.H., Jr. 1989. An illustrated checklist of the American crayfishes (Decapoda: Astacidae, Cambaridae, and Parastacidae). Smithsonian Contributions to Zoology 480:1–236.

Simmons, J.W., and S.J. Fraley. 2010. Distribution, status, and life-history observations of crayfishes in western North Carolina. Southeastern Naturalist 9 (Special Issue 3):79–126.

Skelton, C.E. 2016. Status Assessment for 14 Crayfish Petitioned for Listing. Final Report. United States Fish and Wildlife Service, Athens, GA. 71 pp.

Taylor, C.A., G.A. Schuster, J.E. Cooper, R.J. DiStefano, A.G. Eversole, P. Hamr, H.H. Hobbs III, H.W. Robison, C.E. Skelton, and R.F. Thoma. 2007. A reassessment of the conservation status of crayfishes of the United States and Canada after 10+ years of increased awareness. Fisheries 32:372–389.

Authors of Account

Christopher E. Skelton

Date Compiled or Updated

C. Skelton, June 2008: original account

C. Skelton, January 2019: general update of account.

Photo by Georgia DNR – Wildlife Resources