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Faxonius erichsonianus (Faxon, 1898)
Reticulate Crayfish

Reticulate Crayfish. Photo by Chris Lukhaup. Image may be subject to copyright.
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Federal Protection: No US federal protection

State Protection: No Georgia state protection

Global Rank: G5

State Rank: S4

Element Locations Tracked in Biotics: No

SWAP 2015 Species of Greatest Conservation Need (SGCN): No

SWAP 2025 Species of Greatest Conservation Need (SGCN): No

2025 SGCN Priority Tier: None

Element Occurrences (EOs) in Georgia: 0

Habitat Summary for element in Georgia: Associated with rocks or woody debris in flowing and quiet areas of small streams to medium-sized rivers


Description

The overall color of the Reticulate Crayfish is light brown to olive with darker mottling. There is a dark saddle in front of, and behind the areola. The abdomen is darker than the cephalothorax and there is a thin reddish band at the rear of each abdominal segment. The tips of the fingers of the claws are orangish and there is black pigment just behind the tips. There is an obvious black spot where the movable finger attaches to the palm and the outside edge of the claw is black as well. There are two rows of tubercles along the mesial margin of the palm. The areola is fairly wide and shaped much like an hourglass. The rostrum is long, parallel-sided, and has a long sharp acumen and marginal spines or tubercles. There is a single well-developed cervical spine. This species reaches a maximum total body length of about 88 mm (3.5 in). Note: Based on data presented by Crandall and De Grave (2017), this species was removed from the genus Orconectes and placed in Faxonius.

Similar Species

Based on the prominent black spot where the movable finger attaches to the palm, the only species that could be confused with Reticulate Crayfish is the Coosa Spiny River Crayfish, Orconectes spinosus. These two species have never been collected together in Georgia but have both been found in the Chattooga River system and Pine Log Creek which is a tributary to the Coosawattee River. Examination of the male first pleopod or the female annulus ventralis is required to separate these two species.

Habitat

The Reticulate Crayfish is a stream dweller and can be found beneath rocks or woody debris throughout the streams in which it inhabits.

Diet

No studies of the Reticulate 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 Reticulate Crayfish in reproductive condition have been collected in all months except March, April, August, September, and October. Five females carrying eggs were found in April and 1 with young in May. Egg counts of three of these were 99, 255, and 347. The smallest breeding male known is about 38 mm (1.5 in) and the smallest female carrying eggs is about 48 mm (1.9 in) in length (Hobbs 1981).

Survey Recommendations

Flipping larger rocks in just about any habitat in a stream should turn up this species. The animal can be pinned by hand or gently driven into a dipnet. Dipnetting through leaf packs or using a backpack electroshocker could yield specimens as well.

Range

Reticulate Crayfish ranges from southwestern Virginia to northeastern Alabama in the Tennessee River drainage. In Georgia, it is found in tributaries to the Tennessee River in the northwestern part of the state and also in the Coosa River system. In the Coosa, it is most common in the Chattooga River system, but there are collections from the lower Coosawattee, Armuchee Creek, and a tributary to the Coosa River (Hobbs 1981, 1989).

Threats

Heavy sedimentation resulting from poor development and land management practices may cover substrates and other daytime hiding places on which crayfishes rely to avoid predation. The introduction of non-native crayfishes is a threat to all native crayfishes.

Georgia Conservation Status

This species common and widespread and is apparently stable in Georgia.

Conservation Management Recommendations

Conserving populations of the Reticulate 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

Crandall, K.A., and S. De Grave. 2017. An updated classification of the freshwater crayfishes (Decapoda: Astacidea) of the world, with a complete species list. Journal of Crustacean Biology 2017:1-39.

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.

Authors of Account

Christopher E. Skelton

Date Compiled or Updated

C. Skelton, 2012: original account

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

D.Weiler, September 2019: photo added