Loading profile...

Loading profile. Please wait . . .

Photo by Chris Lukhaup. Image may be subject to copyright.
range map button NatureServe button About button

Cambarus strigosus Hobbs, 1981

Lean Crayfish

Federal Protection: No US federal protection

State Protection: Threatened

Global Rank: G2

State Rank: S2

SWAP High Priority Species (SGCN): Yes

Element Occurrences (EOs) in Georgia: 10

Habitat Summary for element in Georgia: Complex burrows in sandy clay soil, often among roots; Savannah River drainage


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 movable 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

Burrowing crayfishes inhabit a system of tunnels that may be very complex with several openings to the surface. Openings to the tunnels are often marked by piles of dirt or mud pellets (chimneys). Depending on the soil type and moisture content, these chimneys can reach heights of 15 cm (6 inches) or more. These crayfishes are typically confined to their burrows, but a male must leave its burrow to search for females during the reproductive season. As mentioned above, they may also forage near the opening of their burrow. Active burrows with fresh soil are seen from late spring to late fall, particularly after rain events. During the dry part of the summer, burrow openings may be plugged to help conserve moisture in the burrow. Reproduction probably occurs during the spring and fall, but males in reproductive condition may be found at any time during the year. It is very rare to find more than one adult crayfish in the same burrow. When a female crayfish releases her eggs, she 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. Multiple juveniles are occasionally found in a single burrow. 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. Although it is difficult to study burrowing crayfishes, some researchers believe they may live as long as 10 years. 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 to 39 eggs and their egg diameters ranged from 2.0 to 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) 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 2 feet of the surface of the ground.

Range

The Lean Crayfish is currently known from about 15 locations in the Broad River and Little River systems (Savannah River drainage) in northeastern Georgia (Skelton 2016). 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 that could destroy burrows and alter hydrology.

Georgia Conservation Status

This species is considered stable at this time.

Conservation 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.

References

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

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, 2008: original account

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

Photo by Chris Skelton. Image may be subject to copyright.
Photo by Georgia DNR – Wildlife Resources