Native aquatic vertebrates: Conservation and management in the Rio Sonoyta Basin, Sonora, Mexico

The Rio Sonoyta in northern Sonora is an important aquatic ecosystem that is disappearing because of drought and groundwater withdrawal. Its native species are also threatened by introduced species. The only watered reach is an intermittent segment (<1 km, Agua Dulce), found just across the International Border from Organ Pipe Cactus National Monument. The native fish present in the river include the endangered Sonoyta pupfish and the indigenous longfin dace. In the wild, the pupfish occurs only at Quitobaquito Springs and at Agua Dulce. The longfin dace may be extirpated. A partnership formed and led by the La Reserva de la Biosfera El Pinacate y Gran Desierto de Altar included partners from the United States and Mexico to create fish refuges in Mexico. We summarize conservation efforts to maintain native fishes in refuge ponds, report on their status, and offer suggestions for future management. We also present information on the future establishment of refuges for longfin dace and augmentation of pupfish refuges in the United States and Mexico. We briefly discuss the impact of a new wastewater treatment plant on the Sonoyta River.