Date Published or Written
The Rio Yaqui drainage basin of northwestern Mexico comprises about 73,000 km of the most inaccessible and rugged terrain in western North America (Blásquez 1959). An average annual discharge of almost 2,800 ha2 makes the Rio Yaqui one of the major watersheds of that region (Tamayo and West 1964). The small percentage of this system that lies within southwestern United States contributes a substantial proportion of the native ichthyofauna of that area - 6 to 8 species of fishes were originally present, of which 5 did not occur elsewhere in the United States. Changes in land and water uses have largely destroyed these native animals in the United State.s (McNatt 1974), so the presently reported survey wus planned and executed in spring and summer 1978 to determine population status and geographic distributions of those and other fish species in the Mexican portion of the drainage. A review of literature and of specimens in museums completed data upon which this report is based.