Common Name: LEAN CRAYFISH
Scientific Name: Cambarus (Depressicambarus) strigosus Hobbs
Rarity Ranks: G2/S2
State Legal Status: Threatened
Federal Legal Status: None
Description: The overall color of the Lean Crayfish is orangish-olive to bluish-olive with the margins of the rostrum orange to creamy orange. There are two rows of orangish tubercles on the mesial margin of the palm. The areola is very narrow to non-existent and the abdomen appears much narrower than the cephalothorax. The claws may be robust. This species reaches a maximum total body length of about 75 mm (3 in).
Similar Species: The Variable Crayfish (Cambarus latimanus) may occur in close proximity to this species, but it is a dull brownish color and there is space within the areola. The Broad River Burrowing Crayfish occurs with the Lean Crayfish as well, but it is a plain brownish color and the claw shape is much different. On Lean Crayfish, the moveable finger is longer than the mesial margin of the palm, while those lengths are similar on the Broad River Burrowing Crayfish.
Habitat: Complex burrows adjacent to streams or in low areas where the water table is near the surface of the ground.
Diet: No studies of the Lean Crayfish are known and the diet of burrowing crayfishes in general is poorly understood. Crayfishes are considered opportunistic omnivores and likely feed on a variety of items, both plant and animal, living or dead. Burrowing crayfishes may forage around the mouths of their burrows, eat organisms that crawl or fall into the burrow, or eat worms that inadvertently tunnel through a burrow wall.
Life History: Male Lean Crayfish in reproductive condition have been collected in May and October and females with eggs have been collected in April. Clutch sizes for these females ranged from 31-39 eggs and their egg diameters ranged from 2.0-2.1 mm. The smallest first form male known is about 60 mm (2.4 in) and the smallest female with eggs about 54 mm (2.1) in length (Hobbs 1981).
Survey Recommendations: Burrowing crayfishes may be collected by direct excavation of their burrows, by trapping, and during night surveys. Excavating burrows is time consuming and can be very difficult. It also results in destruction of the animals’ burrow. Traps made with PVC pipes or mist nets can be effective. Burrowing crayfishes are sometimes captured around the openings of their burrows on damp nights. Active burrows are found from about mid-March to mid-November if the water table is within about two feet of the surface of the ground.
Range: The Lean Crayfish is currently known from about 10 locations in the Broad River and Little River systems (Savannah River drainage) in northeastern Georgia. It is known from Wilkes, Oglethorpe, and Elbert counties, all of which are part of the Piedmont physiographic province.
Threats: The small range of this species makes it vulnerable to land disturbing activities around streams and wetlands.
Conservation and Management Recommendations: Areas with burrows should be protected from land disturbing activities. Additional surveys and life history studies are needed to better define the range of the Lean Crayfish and help predict its response to environmental change. Environmental education programs should include information about burrowing crayfishes and encourage protection of burrows.
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(8):372-389.
Date Compiled or Updated: September 2012