Densities and Population Sizes of Clinch Dace Chrosomus sp. cf. saylori in the Upper Clinch River Basin in Virginia

Estimates of abundance and density for the imperiled Clinch Dace (Chrosomus sp. cf. saylori) are needed across its range to indicate where populations exist and estimate their long-term viability. We generated estimates of population extent, measured in km of potentially occupied habitat, based on 206 site visits from four fish surveys since 1999 within the Clinch Dace's putative range. Next, we used mark–recapture surveys to estimate Clinch Dace densities in five occupied streams. A linear regression model generated from these data was used to transform single-pass count data into estimated abundance with 90% prediction intervals (PI) for Clinch Dace in sampled reaches. We combined estimates of individual population sizes to estimate global abundance. Finally, we examined the correlation between habitat variables and Clinch Dace abundance in occupied streams. Clinch Dace populations at low densities potentially occupy 31.5 km of the approximately 351 km of 2^nd- and 3^rd-order streams in northern Russell and Tazewell counties in Virginia. Individual population census sizes ranged from 11 to 1,675 individuals. Estimate of combined global census population size for ten of 16 populations was 6,706 (90% PI = 2,847–22,594) adults. Clinch Dace populations are small and isolated. Clinch Dace abundance exhibited weak negative correlation to indices of current and recent surface mining. Regular population monitoring and prompt conservation action are needed to protect Clinch Dace populations, including protecting forested land cover from clearing for logging and mining.