Population Densities of Two Rare Crayfishes, Cambarus obeyensis and Cambarus pristinus, on the Cumberland Plateau in Tennessee

摘要

Cambarus obeyensis (Obey Crayfish) and Cambarus pristinus (Pristine Crayfish) are species of conservation concern, but basic information needed by conservation managers is lacking. To provide a quantitative measure of abundance, we conducted a mark-recapture study at six 100-m reaches per species during May-August 2013. These sites were a subset that we selected from eighty-nine 100-m reaches surveyed during 2011-2013. We built regression models to predict crayfish abundance based on single-pass capture rates for the 12 mark-recapture sites and for all occupied sites identified during the 2011-2013 surveys. We also calculated site-level density and capture efficiency for each species. Cambarus pristinus occurred at significantly lower densities across a larger range than C. obeyensis. Capture efficiency for both species varied across sites, suggesting that monitoring programs should incorporate regular, quantitative estimates of density and capture efficiency. Our results indicate that both species merit ongoing conservation attention and that C. pristinus may represent a higher conservation priority than previously recognized.