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1. Crayfish represent one of the most imperilled animal groups on the planet. Habitat degradation, destruction and fragmentation, introduction of invasive crayfishes, and a lack of applied biological information have all been identified as agents thwarting crayfish conservation. Cambarus callainus was warranted federal protection by the United States Fish and WildlifeService (USFWS) in April, 2016. As part of the USFWS listing procedure, a survey for C. callainus in the Big Sandy River catchment was conducted to determine points of occurrence with a secondary objective of determining reach level physical habitat and physicochemical correlates of C. callainus presence and absence. 3. At each site, physicochemical and physical habitat data were collected to determine the influence of abiotic covariates on the presence of C. callainus. Cambarus callainus presence or absence and associated site covariates were modelled using logistic regression. 4. Survey results recorded C. callainus at 39 sites in the Upper Levisa Fork (ULF) and Tug Fork (TF) drainages of the Big Sandy River; no C. callainus were collected in the Lower Levisa Fork (LLF). An additive effects model of physical habitat quality (Basin + Boulder presence/embeddedness) was the only model selected, supporting an association of C. callainus with slab boulders, open interstitial spaces, and moderate to no sedimentation. All sites lacking C. callainus were experiencing some degree of sedimentation. Physicochemical covariates were not supported by the data.5. Results indicated that good quality habitat was lacking in the LLF, but was present in the ULF and TF catchments, with ULF supporting the most robust populations and most suitable habitat.Effective conservation for C. callainus should focus on efforts that limit sedimentation as well as restore good quality instream habitat in the greater Big Sandy catchment.

surveys were undertaken across the UGB to determine the current distribution of the species. A total of 71 sites were sampled, including all streams where the species was previously recorded, as well as semi-randomly selected streams, with 1-9 125 m long sites sampled per wadeable stream. Physiochemical and physical habitat data (based on the Qualitative Habitat Evaluation Index, QHEI) were obtained at each site to determine abiotic factors that were associated with the presence of C. veteranus. Site detection or non-detection of C. veteranus and associated site covariates were modeled using logistic regression to determine covariates associated with the presence of the species. Cambarus veteranus was present in both the Pinnacle Creek and Clear Fork/Laurel Fork watersheds at 10 sites, but it was not observed in the remaining 61 sites. An additive effects model with conductivity and QHEI was selected as the best approximating model. Cambarus veteranus was associated with lower than average UGB conductivity (379 μS) and high (>80) QHEI score. All sites where C. veteranus was not detected had higher conductivity and/or lower QHEI scores.