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Cambarus howardiChattahoochee Crayfish
Federal Protection: No US federal protection
State Protection: Threatened
Global Rank: G3Q
State Rank: S2
SWAP High Priority Species (SGCN): Yes
Element Occurrences (EOs) in Georgia: 44
Habitat Summary for element in Georgia: riffle areas of streams; in rocks with swift-flowing water
The dorsal surface of the Chattahoochee Crayfish has bronze and bluish-green coloration on the claws, carapace, and on the abdomen. The areola is lavender-brown with hints of green. Thin orange-brown bands mark the separation of the abdominal segments and the joints of appendages. The center of the tail fades from green to yellow-brown posteriorly, and the sutures are a darker orange-brown. The areola is 3–5 times as long as broad and comprises 35–39 percent of the total length of the carapace. Not counting the tail, mature males range in length from 20–33 mm (0.8 to 1.3 in) and mature females range from 20–36 mm (0.8 to 1.4 in). Maximum total length of the species is about 77 mm (3 in).
The Common Crayfish (Cambarus bartonii) and the Variable Crayfish (C. latimanus) are the two most similar species that may occur with the Chattahoochee Crayfish. Neither of these species displays the distinctive bluish-green coloration seen on the Chattahoochee Crayfish.
The Chattahoochee Crayfish has been found in clear, free-flowing waters, often in riffle habitat. It has been collected in a range of stream sizes, from smaller tributary streams to the mainstem Chattahoochee River. During daylight, specimens are usually found sheltered under rocks. Individuals are typically found in shallow waters, but this may be a result of sampling bias.
No studies of the Chattahoochee Crayfish diet are known. Crayfishes are considered opportunistic omnivores and likely feed on live and decaying vegetation, aquatic insect larvae, 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. The only life history information published for Chattahoochee Crayfish were notes by Hobbs (1981). Males in reproductive condition have been collected from January to October. Females carry eggs in the late spring, which hatch in early summer. Two females had 20–42 eggs, which ranged in size from 2.2–2.3 mm.
Since this species is usually found in swift 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. Disturbing submerged collections of leaves and twigs upstream from a net may also productive as well as shocking downstream into a seine net with a backpack electroshocker. Because crayfish are typically more active at night, trapping may also be effective.
The Chattahoochee Crayfish is distributed within the Chattahoochee River system in Cobb, DeKalb, Douglas, Forsyth, Fulton, Hall, Harris, and Lumpkin counties in Georgia. Additional drainage records have been discovered in the past few years including locations in the upper Flint River system in Coweta County, and the upper and middle Oconee River system in Barrow and Newton counties.
Chattahoochee Crayfish is threatened throughout most of its range by residential development and a corresponding degradation of water quality. Much of the suitable habitat within the range of the Chattahoochee Crayfish has been inundated by Lake Lanier and other, smaller impoundments. Other habitat has been paved over by highways and replaced by underground culverts. Other urbanization impacts include removal of riparian zone vegetation, hydrological alteration, and runoff of pollutants. Observations made during a recent field study suggest that the Chattahoochee Crayfish has been lost from streams impacted by forest clearing, sedimentation, urbanization, and impoundment. The introduction of non-native crayfishes is a threat to all native crayfishes.
This species is considered to be stable at this time.
Conserving populations of the Chattahoochee Crayfish will require general watershed-level conservation and restoration practices. These efforts should be targeted in watersheds where healthy populations remain and would include restoration and enhancement of stream buffers, preservation of uplands, and better stormwater management practices.
Bouchard, R.W. 1976. Crayfishes and Shrimps. In: Herbert Boschung, editor, Endangered and Threatened Plants and Animals of Alabama. Alabama Museum of Natural History Bulletin 2:13–20.
Hobbs, H.H., Jr. 1981. The crayfishes of Georgia. Smithsonian Contributions to Zoology 318:1–549.
Hobbs, H.H., Jr., and E.T. Hall, Jr. 1969. New crayfishes from Georgia (Decapoda, Astacidae). Proceedings of the Biological Society of Washington 82:281–294.
Stanton, G.E. 2006. Evaluation of conservation status of six West Georgia, Chattahoochee-Flint River crayfish species. Final Report. Georgia Department of Natural Resources, Social Circle, GA. 60 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.
Yarbrough, J.E. 1973. An ecological and taxonomic survey of the crayfish of the Tallapoosa and Chattahoochee River drainages in Lee County, Alabama. Master’s Thesis. Auburn University, Auburn, AL. 96 pp.
George E. Stanton
G. Stanton, June 2008: original account
C. Skelton, January 2019: general update of account.