Common Name: TANBACK RAYFISH
Scientific Name: Cambarus (Hiaticambarus) girardianus Faxon
Rarity Ranks: G5/S4
State Legal Status: None
Federal Legal Status: None
Description: The Tanback Crayfish is distinctly patterned. There is a dark brown band on the head region in front of the areola and another dark brown band at the rear of the carapace which creates a saddled appearance. The areolar region is tan to brown. There is a broad, dark brown stripe down the center of the abdomen which narrows posteriorly. On each side of this dark stripe are pale stripes which are in turn flanked laterally by thinner dark stripes along the edges of the abdomen. The fingers of the claws have a gap between them when they are closed and there is typically a patch of hairlike setae at the base of the fixed finger of the claw. There is a single row of tubercles along the mesial margin of the palm and the areola is wide. The edges of the rostrum are orangish-red and the rostrum may or may not have marginal tubercles or spines. A single cervical spine or tubercle is usually present. This species reaches a maximum total body length of about 86 mm (3.4 in).
Similar Species: The combination of gaping fingers of the claws and the broad dark stripe down the center of the abdomen separates the Tanback Crayfish from all species with which it occurs in Georgia.
Habitat: The Tanback Crayfish is a stream dweller and can be found in small spring runs less than 1 m wide to the mainstem of medium sized rivers like West Chickamauga Creek. It can be found in swiftly flowing waters as well as quieter areas and is usually associated with rocks or other debris.
Diet: No studies of the Tanback Crayfish are known. Crayfishes are considered opportunistic omnivores and likely feed on live and decaying vegetation, aquatic insect larvae, small fishes, and dead animal matter.
Life History: Male Tanback Crayfish in reproductive condition have been collected in April, May, October, and November and seven females carrying eggs were found in April. The smallest male from Georgia is about 48 mm (1.9 in) and the smallest female with eggs is about 51 mm (2 in). Number of eggs ranged from 83 to 224 (Hobbs 1981).
Survey Recommendations: Since this species is usually found in flowing water, it is most easily collected by holding a net perpendicular to the current downstream of a large rock, then lifting the rock and disturbing the substrate beneath it. If a crayfish is hiding underneath the rock, it will likely move into the net. Shocking downstream into a seine net with a backpack electroshocker is also effective. In quieter areas of the stream, rocks can be turned gently, and after the water clears either pin the crayfish by hand or coax it into a dipnet.
Range: The Tanback Crayfish inhabits the upper-middle and upper Tennessee River system in Alabama, Georgia, Mississippi, and Tennessee. In Georgia it is known only from Tennessee River tributaries in the northwestern portion of the state (Hobbs 1981; 1989).
Threats: This species is apparently secure across its range.
Conservation and Management Recommendations: Conserving populations of the Tanback 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 where they will be fishing. Unused bait of any kind should not be released back into Georgia waters.
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.
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(8):372-389.
Date Compiled or Updated: August 2012