9425 - Laserfiche WebLink

Home Browse Search

1 1 1 1 Historical distribution summary-Although historically distributed throughout cool and warmwater reaches of the CRB (Figures 4 and 5), two roundtail chub population centers are evident. One is located in-the Gila River Basin and the other is found in the UCRB. _Lower Colorado River Basin. Roundtail chubs were once common in most Gila River Basin streams, occurring near the mouth of the Gila River, and upstream of the Salt River confluence from approximately 300 to 2,000 meters elevation. Historic collections of Gila robusta in the Gila River Basin are available only from near the mouth of the Gila River and higher in the basin, most likely because fish surveys in the lower river (below Phoenix) were rare prior to its drying after construction of the Ashurst/Hayden Dam (Bettaso pers. comm. 2002). Although now only found in the Gila River alcove Red Rock, New Mexico, previous collections documented roundtail chub downstream to the New Mexico-Arizona. state i t 1 line. Roundtail chub were also historically collected from the Bill Williams River drainage, and from the upper Little Colorado River drainage including Chevelon and Clear creeks. In the lower Colorado River, roundtail chubs appear to have been less common in Glen and Grand Ganyan and were infrequently collected downstream from present-day Lake Mead. Although historic collections note Gila robusta from streams of the pluvial White River drainage, Nevada, we refer these specimens to Gila seminuda (DeMarais et al. 1992) and will not further discuss these collections. Unner Colorado River Basin. In the UCRB, roundtail chubs historically occurred in most rivers and streams below approximately 2,300 meters elevation, including the Green, Colorado, Yampa, Gunnison, Dolores, San Juan, White, Duchesne, Price, San Rafael, and Escalante rivers and numerous tributaries (Figures 4 and 5). However, it appears they were never common in some low velocity river reaches of the Green and Colorado rivers such as the Uintah Basin and Labyrinth, Stillwater, and Glen canyons. They were also uncommon in the Lower San Juan River, Utah. Final Report September 2002 24