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Cambarus striatus Hay, 1902
Ambiguous Crayfish
Federal Protection: No US federal protection
State Protection: No Georgia state protection
Global Rank: G5
State Rank: S5
Element Locations Tracked in Biotics: No
SWAP High Priority Species (SGCN): No
Element Occurrences (EOs) in Georgia: 0
Habitat Summary for element in Georgia: Complex burrows in low wet areas, or associated with rocks in flowing areas of small streams to medium-sized rivers in northern portions of range
Depending on the population encountered, the Ambiguous Crayfish may exhibit a striped or non-striped color pattern; occasionally both patterns will be present in the same population. The overall color ranges from olive or light brown to orangish brown. Striped individuals have paired dark longitudinal stripes on the abdomen which may carry forward onto the carapace. The areola is very narrow, almost obliterated. The rostrum is wide, relatively short, and does not have marginal spines or tubercles. There are two rows of tubercles along the mesial margin of the palm. A small, single cervical tubercle is rarely present. This species reaches a maximum total body length of about 120 mm (4.7 in).
Across most of its range, the Ambiguous Crayfish is most similar to the Variable Crayfish, Cambarus latimanus. According to Hobbs (1981) the two are sometimes impossible to separate. The areola on the Variable Crayfish is typically not as narrow and the rostrum is longer and narrower than Ambiguous Crayfish. Careful study will be required for positive identification where the two species overlap. In the Conasauga basin, Ambiguous Crayfish closely resembles the Cocoa Crayfish (Cambarus stockeri); however, the latter has more than two rows of tubercles on the palm.
In some parts of its range in Georgia, the Ambiguous Crayfish is a secondary burrower and can often be found in flowing streams (e.g. Conasauga River system) and streamside burrows. When in streams, it is usually found beneath rocks or within woody debris. Farther south the species is rarely found in open water and acts more like a primary burrower.
No studies of the Ambiguous 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.
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 Ambiguous Crayfish in reproductive condition have been collected in all months except February, July, and August. Three females carrying eggs were found in April (Bouchard 1978). The smallest breeding male known is about 48 mm (2.5 in) in length (Camp et al. 2011) and no females with eggs have been collected. The largest female specimen collected is about 90 mm (3.5 in) in length (Bouchard 1978).
In the Conasauga River system, flipping rocks within streams should reveal this species. In other portions of the range, the species is apparently restricted to burrows which will have to be excavated or trapped.
The Ambiguous Crayfish is a widespread species found from Mississippi to western South Carolina and north to Kentucky. In Georgia it is most commonly found in the northwestern portion of the state with scattered populations south and east. It is found all the way to the Florida state line in the Chattahoochee and Flint river systems but has not been found farther south than the Altamaha in river systems that flow to the Atlantic Ocean (Hobbs 1981, 1989).
Activities that destroy burrows or alter hydrology in the vicinity of burrows threaten this and other burrowing species.
This species is widespread and common and considered stable in Georgia.
General watershed level protection measures will help secure the continued existence of the Ambiguous Crayfish in Georgia. These include 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. If possible areas with burrows should be protected from land disturbing activities and activities that could alter groundwater resources. Environmental education programs should include information about burrowing crayfishes and encourage protection of burrows.
Bouchard, R.W. 1978. Taxonomy, ecology, and phylogeny of the subgenus Depressicambarus, with the description of a new species from Florida and redescriptions of Cambarus graysoni, Cambarus latimanus, and Cambarus striatus (Decapoda: Cambaridae). Alabama Museum of Natural History Bulletin 3:26-60.
Camp, M.A., C.E. Skelton, and C.B. Zehnder. 2011. Population dynamics and life history of the Ambiguous Crayfish (Cambarus striatus). Freshwater Crayfish 18:75-81.
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 32:372–389.
Christopher E. Skelton
C. Skelton, 2012: original account
C. Skelton, February 2019: general update of account.