Dimensions of dace dynamics: temporal variation in abundance and survival of an imperiled desert fish guide habitat restoration

Introduction Desert fishes are vulnerable to anthropogenic environmental alterations that degrade habitat and reduce water availability, but these same fishes benefit from restoration actions that reverse the causes of decline. Ash Meadows speckled dace ( Rhinichthys osculus nevadensis ) is a federally endangered minnow endemic to the Mojave Desert at Ash Meadows National Wildlife Refuge, Nevada, United States and is considered in need of conservation because of anthropogenic alterations to habitats they occupy. Objectives This study aims to establish quantitative associations between dace populations and environmental gradients that exist at Ash Meadows National Wildlife Refuge to guide restoration and management activities. Methods We fit an open‐population generalized N ‐mixture model using environmental and repeated count data collected across four seasons to assess environmental covariates for abundance, detection, and apparent survival of Ash Meadows speckled dace. We also used total length data to analyze age structure and make inferences on recruitment and movement. Results We found that dace abundance was highest in habitats with deeper water and denser canopy cover; detection was greatest in habitats with open canopies and when surveys were conducted earlier in the day and used longer trap soak times; and apparent survival was highest at locations with denser canopy cover. We also found evidence of recruitment and recolonization in restored habitats across the refuge. Conclusions The tools and framework we apply here are applicable to other freshwater ecosystems afflicted by anthropogenic alterations and where restoration decisions require abundance‐based information for organisms in need of conservation.