Bonita Creek native fish restoration

Authors: Heidi B. Blasius, Codey Carter, Robert Clarkson, Glen Knowles, Mary Richardson, Ross J. Timmons, David L. Ward

Year: 2009 (xli)

Abstract

Native fishes historically found in the Gila River basin have suffered significant declines in abundance and distribution due to nonnative fishes and habitat loss and degradation. To reverse this trend, nonnative fishes must be segregated from native fishes and the habitat protected to prevent future reinvasions. Bonita Creek, Graham County, AZ, is considered a high priority for native fish recovery in the Gila River basin due to its assemblage of five native fishes (Gila chub, Gila intermedia, longfin dace, Agosia chrysogaster, speckled dace, Rhinichthys osculus, Sonora sucker, Catostomus insignis, and desert sucker, Pantosteus clarki) uncontaminated by nonnative fishes and other nonnative aquatic organisms in upper reaches of the stream, habitats appropriate for introduction of additional federally-listed fishes native to the Gila River basin, and its potential to be protected against impacts/invasions of nonnative fishes by constructing a fish barrier and chemically removing the nonnatives. For native fish recovery, a fish barrier was constructed across Bonita Creek by the Bureau of Reclamation in 2008. The barrier is a 160-foot wide concrete-reinforced arched structure with a four-foot tall crest, and is protected against stream scouring with sunken keys and rip-rap emplaced downstream of the apron. To remove nonnative fish species, Bonita Creek was chemically renovated. Renovation included and required beaver pond breaching, native fish salvage, chemical application of the piscicide rotenone (CFT Legumine), and repatriation of the salvaged natives. To facilitate the project, approximately 46 beaver ponds were temporarily breached to lower the pools and to establish greater flow, which was necessary to effectively disperse the piscicide through the stream. Prior to chemical treatment, native fish and Sonora mud turtles were salvaged using a combination of electrofishing, seines, hoop nets, and minnow traps. Captured native fishes were held in flow-through holding tanks. To determine the amount of rotenone necessary, stream discharge and volume were calculated using direct measurements and a fluorescent dye. Rotenone was applied using constant-flow drip stations while roving crews treated shallow backwaters and poorly-mixed shorelines with backpack sprayers. Approximately 2.6 miles of stream was chemically treated twice. To verify a complete kill after the piscicide treatment, hoop nets and minnow traps were set in pool and run habitats and the entire creek was electrofished. No fish were found alive. Sentinel native fish were placed into live cars for two days to ensure the stream had detoxified before the salvaged fish and turtles were repatriated back to the stream near the general vicinity from where they were captured. Federally-listed loach minnow, Tiaroga cobitis, spikedace, Meda fulgida, desert pupfish, Cyprinodon macularius, and Gila topminnow, Poeciliopsis occidentalis were also introduced following detoxification. The project was a collaborative effort among Arizona Game and Fish Department, Bureau of Land Management, Bureau of Reclamation, U.S. Fish and Wildlife Service, City of Safford, Arizona State University, University of Arizona, and public volunteers.