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9 fishes and the endemic Colorado River fishes. Because these endemic fishes have evolved under natural conditlons of high turbidity, it is assumed that the retention of these highly turbid conditions is important for the recovery of these endangered fishes. Reduction of turbidity may enable introduced species to gain a competitive edge which could further contribute to the decline of the endangered Colorado River fishes. Colorado Squawfish Activitv in the 15-mile Reach The Grand Valley area is occupied year round by Colorado squawfish. The 15-mile reach is the section of river between the Grand Valley Diversion and the confluence with the Gunnison River. It has been identified as important habitat for Colorado squawfish. Migration Radio-telemetry studies show upstream and downstream movement of adult Colorado squawfish in the main stem Colorado River. The most dramatic movement was exhibited by a fish implanted with a radio transmitter at Gypsum Canyon in upper Lake Powell on April S, 1982. The fish was contacted next in the lower Cataract Canyon area on July 9. 1982. The next contact was made above the Black Rocks area of Ruby Canyon, some 160 miles upstream. The movement was accomplished in 41 days and is believed to be related to spawning. At the end of September 1982, this fish was located in the Colorado River in the vicinity of Clifton. Colorado (river mile 178). nearly 200 river miles from its furthest documented downstream location. Other radio-tagged fish in the Colorado River have not displayed such dramatic migratory behavior. Radio-telemetry studies conducted by the Colorado River Fishery Project (Fishery Project) from 1982-1989 (Miller et a1. 1982: Archer et al. 1986: Osmundson and Kaeding 1989), which focused on upstream reaches ~f the Colorado River in and around the Grand Valley, provide the best indication of use of the 15-mile reach above the confluence of the Gunnison River at one time or another during the field season. Movement of these fish during a field season was generally limited to 25-30 miles. During 1986-1988, the Fishery Project radio telemetered 17 adult Colorado squawfish collected from the IS-mile reach above the Gunnison River in June (Osmundson and Kaeding 1989). The fish exhibited a diversity of localized movement throughout the Grand Valley but spent a major part of time in the 15-mile reach. Two remained in the reach throughout the estimated spawning period.