Evaluation and Refinement of Guadalupe Bass Conservation Strategies to Support Adaptive Management

The Cooperator Science Series was initiated in 2013. Its purpose is to facilitate the archiving and retrieval of research project reports resulting primarily from investigations supported by the U.S. Fish and Wildlife Service (FWS), particularly the Wildlife and Sport Fish Restoration Program. The online format was selected to provide immediate access to science reports for FWS, state and tribal management agencies, the conservation community, and the public at large. Guadalupe Bass has experienced declines in parts of its range due to habitat degradation and introgressive hybridization with Smallmouth Bass. Efforts to restore Guadalupe Bass have been ongoing in the Guadalupe River drainage for over twenty years, but have recently been expanded to the Llano River drainage. Conservation and restoration efforts in the South Llano River have included supplemental stocking of non-hybrid fingerlings as well as landscape-level restoration projects in riparian and upland areas to benefit the river system. To further this effort, we undertook a multifaceted approach to evaluate Guadalupe Bass population characteristics as well as habitat use patterns in order to refine conservation and restoration strategies. Catch per unit effort was highest in sites containing swift moving water and large woody debris while abundances were lower in pool habitats with bedrock substrates. Additionally, population estimates resulted in densities of Guadalupe Bass that were highest in the sub-reaches possessing greater amounts of riffle and run habitats. Evaluation of current introgression rates indicates that introgression has declined from 3.9% to 0.9% as stocking has occurred. Our results suggest that maintaining flows is critical to providing highly utilized habitat types and that supplemental stocking is an effective management tool for reducing introgression rates in Guadalupe Bass.