BIO-WEST is assessing the distribution and ecology of native fishes by conducting various endangered species studies and providing guidance and advice on endangered species issues in the Virgin River system. Past research activities have included native fish surveys of standard monitoring reaches on the lower Virgin River and a study to evaluate the impact of red shiner (Cyprinella lutrensis) removal on woundfin stocking success. The Virgin River fishery study involves sampling for endangered woundfin (Plagopterus argentissimus) and Virgin River chub (Gila seminuda) in the Arizona and Nevada portions of the Virgin River. Other aspects of the study include conducting baseline fisheries surveys, making recommendations on habitat improvement, and establishing a monitoring plan for native fishes in the study reach. BIO-WEST also studied the feasibility of mechanically removing red shiner from a reach of river that received experimental woundfin supplementation. Currently, BIO-WEST is conducting biannual sampling trips on the lower Virgin River to assess native and nonnative fish distribution and abundance. We also sample during the summer months to evaluate the potential for blue tilapia (Oreochromis aurea) invasions from Lake Mead. Cumulatively, these current activities provide an understanding of the fish community of the lower Virgin River.