TIMOTHY A. BONNER, GENE R. WILDE, AND RICARDO JIMENEZ, JR., Department of Range, Wildlife, and Fisheries Management, Texas Tech University, Lubbock, Texas 79409, USA

Fish assemblages of the Canadian River historically were relatively uniform in composition across the Texas Panhandle and were dominated by plains minnow Hybognathus placitus and Arkansas River shiner Notropis girardi. These two species comprised > 90% of fishes collected from the Canadian River in 1954-1955. Construction of two reservoirs in the mid-1960s, Ute Reservoir in New Mexico and Lake Meredith in Texas, changed hydraulic conditions in the Canadian River. Downstream from Lake Meredith, flows have been reduced approximately 88% compared with historic flows. Since the 1950s, the relative abundance of plains minnow and Arkansas River shiner have decreased with both species comprising < 1% of fishes collected in 1996. The relative abundance of red shiner Cyprinella lutrensis and sand shiner Notropis stramineus have increased with both species comprising 45% of fishes collected in 1996. Upstream from Lake Meredith, flows have been reduced by about 50% from historic levels. The relative abundance of plains minnow has decreased from 65% of fishes collected in the 1950s to 32% in 1996, the relative abundance of Arkansas River shiner has remained at about 24%, and speckled chub Macrhybopsis aestivalis has increased in relative abundance from < 1% to 24% of fishes collected during the 1990s.