Life history of the Big Sandy crayfish Cambarus callainus Thoma, Loughman & Fetzner, 2014 (Decapoda: Astacoidea: Cambaridae), an imperiled crayfish in the central Appalachian coalfields, USA

The Big Sandy crayfish, Cambarus callainus Thoma, Loughman & Fetzner, 2014, endemic to the Big Sandy River basin in the central Appalachians, USA, was listed by the United States Fish & Wildlife Service as threatened under the Endangered Species Act in 2016 due to limited and declining range. In March 2018 we began a twelve-month study of the species at the Dry Fork watershed in West Virginia, USA and the Russell Fork watershed in Virginia, USA to document annual life history, reveal if seasonal molting occurs, determine the reproductive season and fecundity, and define its life history strategy. Egg-bearing females were only captured in August; however, a single female was collected with free-living craylings in April, suggesting possible overwintering maternal care or a potential early spring oviposition event. Mating likely occurred between May and June and potentially into the fall and early winter. Five to six size-class cohorts were observed, and we speculate that C. callainus could live up to five years or more. Analysis of morphometric data suggests that females undergo form change, displaying larger chelae and wider abdomens. The smallest Form I male collected had a total carapace length (TCL) of 31.5 mm and the smallest Form I female 32.8 mm. The largest male collected was Form I with a TCL of 55.9 mm. Similar to other species of Cambarus, C. callainus appears to exhibit K-selected life history traits: Fewer and larger eggs, relatively longer maternal care, larger but slow growing, and long lived. The life history information described should prove invaluable to those engaging in conservation efforts for this threatened species.