Distocambarus

Abstract: Conservation status.—Endangered (Taylor et al., 2007), critically imperiled in South Carolina and globally (S1, G1; South Carolina Comprehensive Wildlife Conservation Strategy 2005-2010, [SC CWCS] 2005). Based on the species’ limited distribution (, 20,000 km) and its observed decline at population sites (Eversole, 1995a, b, unpublished data) D. youngineri has been classified as vulnerable, VU B1b (i, iv), following IUCN (2001).

Abstract: Distocambarus crockeri Hobbs and Carlson, 1983 (piedmont prairie burrowing crayfish) burrows were excavated monthly from April through July 2005 and September 2005 through June 2006 at a terrestrial site in South Carolina. Crayfish were counted, measured (carapace length in mm, CL), sexed, and life stage determined. Number, size and life stage of crayfish per burrow varied within and among months. Burrow excavation yielded ovigerous females in spring and a new cohort of young-of-the-year (YOY) crayfish in June 2005 and 2006. Burrows contained both sexes of adult (≥27 mm CL) and juvenile (<27 mm CL) crayfish, male reproductive forms, and YOY. The sex ratio of 394 adult and juvenile (0.80:1) crayfish favored females. Rarely were burrows observed with more than two adult or juvenile individuals and YOY crayfish with juveniles were not observed in the same burrow. Young-of-the-year crayfish were observed in 28.7% of excavated burrows ( n = 359 ) and these YOY accounted for 81% of the 2116 crayfish excavated. Mean burrow occupancy decreased from 14.9 crayfish/burrow in September 2005 to 1.2 in March 2006 before increasing to 6.3 crayfish/burrow in June 2006. The decrease in the 2005-year class YOY crayfish from parental burrows through mortality and emigration, instantaneous rate of loss ( Z ′ ), was estimated at 0.008. The von Bertalanffy growth model: CL = 36 . 62 ∗ ( 1 − 0 . 8236 6 ( − 0 . 2219 ∗ t ) ) derived from mark-recapture CL data provide an estimated first age of reproduction of 5.1 years for this D. crockeri population.