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Cambarus hiwasseensis Hobbs, 1981

Hiwassee Crayfish

Federal Protection: No US federal protection

State Protection: No Georgia state protection

Global Rank: G3G4

State Rank: S3

SWAP High Priority Species (SGCN): No

Element Occurrences (EOs) in Georgia: 16

Habitat Summary for element in Georgia: Clear streams with swift flow and rocky substrate


Description

The overall color of the Hiwassee Crayfish is light brown with darker mottling. On the abdomen, there is a series of darker scalloped markings on each segment creating a slightly striped appearance. The claws are olive-brown. There are two rows of tubercles along the mesial margin of the palm and the areola is wide. The rostrum essentially tapers throughout its length and never has marginal tubercles. A single small cervical tubercle is usually present. This species reaches a maximum total body length of about 80 mm (3.1 in).

Similar Species

The Hiwassee Crayfish is very similar to the Hiwassee Headwater Crayfish, Cambarus parrishi. Although they both occur in the upper Hiwassee River system in Georgia and North Carolina they have never been collected at the same site in Georgia and have been collected together only once in North Carolina (Simmons and Fraley 2010). The only reliable difference separating the two is the Hiwassee Headwater Crayfish has marginal spines or tubercles on the rostrum, while the Hiwassee Crayfish does not. It may take magnification to discern the tubercles on the Hiwassee Headwater Crayfish. The Hiwassee Crayfish has been collected with the similar looking Common Crayfish, Cambarus bartonii. The claws of the Hiwassee Crayfish have two rows of tubercles along the mesial margin of the palm, while those of Common Crayfish have a single row.

Habitat

The Hiwassee Crayfish is a stream dweller and is found in flowing areas among rocks and debris trapped among rocks.

Diet

No studies of the Hiwassee 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

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. Male Hiwassee Crayfish in reproductive condition have been collected in all months except January, February, July, September, and December. Coincidentally, these are the months in which no collections have been made so it seems possible that reproductive males may be found at any time of the year. One female carrying eggs and young was collected in June and had 13 eggs and 51 young attached; she was about 60 mm (2.4 in) total length. The smallest breeding male known is about 50 mm (2 in) in length (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 slowly and coaxing the crayfish into the dipnet. Shocking downstream into a seine net with a backpack electroshocker and setting baited minnow traps overnight can also be effective.

Range

The Hiwassee Crayfish is known from the upper Hiwassee River system in Georgia and North Carolina. In Georgia it can be found in the Hiwassee and Nottely rivers and Brasstown Creek (Hobbs 1981, Simmons and Fraley 2010).

Threats

This species is apparently secure across its range although increased residential development in the North Carolina portion of its range (Simmons and Fraley 2010) and in northern Georgia warrants monitoring of this species.

Georgia Conservation Status

The species is considered stable in Georgia. Some Georgia populations occur on US Forest Service property which are somewhat protected.

Conservation Management Recommendations

Conserving populations of the Hiwassee 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.

References

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

Simmons, J.W. and S.J. Fraley. 2010. Distribution, status, and life-history observations of crayfishes in western North Carolina. Southeastern Naturalist 9 (Special Issue 3):79–126.

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, August 2012: original account

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