Current status of the threatened spotfin chub (Erimonax monachus) and the endandered duskytail darter (Etheostoma percnurum) in Abrams Creek, Great Smoky Mountains National Park

Abrams Creek is located in the southwestern portion of Great Smoky Mountains National Park (GRSM) within Tennessee. In 1957, GRSM fisheries biologists utilized rotenone to extirpate 46 fish species from the lower 23.5 km of Abrams Creek. Four of the extirpated fish species are currently federally listed as threatened or endangered, including spotfin chub Erimonax monachus and duskytail darter Etheostoma percnurum. Between 1988 and 2001, Conservation Fisheries Inc. (CFI) reintroduced these two species into lower Abrams Creek. The objectives of this study were to: (1) determine current distributions of duskytail darters and spotfin chubs in Abrams Creek from Abrams Falls to Chilhowee Reservoir; (2) quantify amount of utilized macrohabitat for each species; (3) determine current recovery status for each species; (4) determine factors influencing dispersal and abundance of duskytail darters and spotfin chubs at the macrohabitat level; and (5) quantify impacts of stream alteration by visitors and determine effects on reintroduced species.;Twenty-seven randomly selected 200-m reaches were delineated throughout the 17.4 km of lower Abrams Creek encompassing reintroduction sites. Habitat variables were measured and snorkeling surveys were conducted to determine presence or absence of each species within each reach during summers of 2007 and 2008. Stepwise logistic regression was used to build the strongest predictive model relating probability of species presence to significant habitat variables. Linear relationships between relative abundance and distance from, as well as densities at, reintroduction sites were analyzed to determine dispersal trends. Bimonthly stream morphology characterization and snorkeling surveys were conducted during summer 2008, within a reach prone to visitor-induced substrate alteration, to determine effects on presence of reintroduced species. Drainage area and connectivity of watersheds with natural extant spotfin chub populations were compared with Abrams Creek watershed to determine large-scale differences.;Duskytail darters were observed in a 4-km section of the study area. Percentage of cobble substrate was identified as the only significant (P=0.0227) macrohabitat variable influencing their presence. Relative abundance was positively related to total stocking densities over time (R2=0.9694, P=0.0004) and negatively related to distance from closest upstream reintroduction site (R2=0.9282, P=0.0366). Visitor-induced stream alteration did not affect presence of duskytail darters. No spotfin chubs were observed in lower Abrams Creek. Watershed analysis revealed downstream connectivity of free-flowing water as a potential factor influencing spotfin chub absence in Abrams Creek.