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Cambarus conasaugaensisMountain Crayfish
Federal Protection: No US federal protection
State Protection: No Georgia state protection
Global Rank: G3
State Rank: S3
SWAP High Priority Species (SGCN): No
Element Occurrences (EOs) in Georgia: 26
Habitat Summary for element in Georgia: Rocky portions of medium sized rivers, cascading mountain streams, and seepage areas
The overall color of the Mountain Crayfish is reddish or orangish-brown to olive-green. This species has a single row of well-developed tubercles on the mesial margin of the palm with some obvious setae present on the fingers. The rostrum is relatively short, wide, and gradually tapering; areola wide. This species reaches a maximum total body length of about 70 mm (2.75 in).
The Mountain Crayfish has been collected with Variable Crayfish (Cambarus latimanus) and Ambiguous Crayfish (C. striatus), both of which have two rows of tubercles on the mesial margin of the palm. It has also been collected within the ranges of Etowah Crayfish (C. fasciatus), Coosawattee Crayfish (C. coosawattae), and Beautiful Crayfish (C. speciosus). All three of these species differ from Mountain Crayfish by having a gap between the fingers of the claw when the fingers are closed versus the fingers essentially touching when closed. It is most likely to be confused with the similar Common Crayfish (C. bartonii) which also has a single row of tubercles on the palm. The tubercles of C. bartonii are not as well-developed (they are flattened) on the palm and there are no obvious setae on the fingers of the claws.
The Mountain Crayfish can be found in a wide variety of habitats including rocky portions of medium sized rivers, cascading mountain streams, and seepage areas. It tunnels among rocks and may construct complex burrows at stream edges. Hobbs (1981) suggested it occurs only above an elevation of 400 m.
No studies of the Mountain Crayfish are known. Crayfishes are considered opportunistic omnivores and likely feed on live and decaying vegetation, aquatic insects, small fishes, and dead animal matter.
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. Male Mountain Crayfish in reproductive condition have been collected in April, June, September, and October. Females carrying eggs are known from April and June. Numbers of eggs for three specimens were 27, 33, and 53. The smallest breeding male known is about 60 mm (2.3 in) and the smallest female with eggs is about 56 mm (2.2 in) in length (Hobbs 1981).
This species can be difficult to find; it is typically not found beneath a single rock on the surface of the stream bed like many species. Rather, this species essentially tunnels among rocks and a surveyor must patiently remove rocks one at a time in the proper habitat and catch the crayfish by hand or coax it into a dipnet.
In Georgia, Mountain Crayfish are known from the Blue Ridge, upper Piedmont, and Ridge and Valley physiographic provinces in the upper portions of the Conasauga and Etowah rivers and the Coosawattee River system above Carters Lake. In Tennessee they have been collected from tributaries to the Ocoee River (Hiwassee River tributary) in Polk County.
There is increased development within some of the areas where this species lives. With more development comes an increase in impervious surfaces. This can lead to more frequent and severe stormwater flows that carry toxins and increase water temperatures these threats are harmful to all aquatic life. Heavy sedimentation resulting from poor development and land management practices may cover substrates and other daytime hiding places on which crayfishes rely to avoid predation. The introduction of non-native crayfishes is a threat to all native crayfishes.
This species is widespread and common and apparently stable in Georgia.
Conserving populations of the Mountain 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. 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.
Hobbs, H.H., Jr. 1981. The crayfishes of Georgia. Smithsonian Contributions to Zoology 318:1–549.
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.
Christopher E. Skelton
C. Skelton, 2012: original account
C. Skelton, January 2019: general update of account.
DW, August 2019: added Lukhaup photo