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<br />. <br /> <br />. <br /> <br />. <br /> <br />,MFlY-15-1998 15:49 <br /> <br />BOR LULND <br /> <br />9706633212 P.09/24 <br /> <br />8 <br /> <br />these endangered fishes. Reduction of turbidity may enable introduced species <br />to gain a competitive edge which could further contribute to the decline of <br />the endangered Colorado River fishes. <br /> <br />Colorado Sauawfish Activity in the IS-mile Reach <br /> <br />The Grand Valley area is occupied year round by Colorado squawfish. The <br />IS-mile reach is the section of river between the Grand Valley Diversion and <br />the conflUence' with the Gunnison RiYer. It has bun identified as important <br />habitat for Colorado squawfish. <br /> <br />Micration <br /> <br />Radio-telemetry studies show upstream and downstream movement of adult <br />Colorado squawfish in the main stem Colorado RiYer. The most dramatic <br />movement was exhibited by a fish implanted with a radio transmitter at Gypsum <br />Canyon in upper Lake Powell on AprilS, 1982. The fish was contacted next in <br />the lower Cataract Canyon area on July 9, 1982. The next contact was made <br />above the Black Rocks area of Ruby Canyon, some 160 miles upstream. The <br />movement was accomplished in 41 days and is believed to be related to <br />spawning. At the end of ,September 1982, this fish was located in the Colorado <br />River in the vicinity of Clifton, Colorado (river mile 178), nearly 200 river <br />miles from its furthest documented downstream location. <br /> <br />Other radio-tagged fish in the Colorado RiYer have not displayed such dramatic <br />migratory behavior. Radio-telemetry studies conducted by the Colorado River <br />Fishery Project (Fishery Project) from 1982-1989 (Miller et al. 1982; Archer <br />et al. 1986; Osmundson and Kaeding 1989), which focused on upstream reaches of <br />the Colorado River in and around the Grand Valley, provide the best indication <br />of use of the IS-mile reach above the confluence of the Gunnison Riyer at one <br />time or another during the field season. Movement of these fish during' a <br />field season was generally limited to 25-30 miles. <br /> <br />During 1986-1988, the Fishery Project radio telemetered 17 adult Colorado <br />squawfish collected from the IS-mile reach above the Gunnison River in June <br />(Osmundson and Kaeding 1989). The fish exhibited a diversity of localized <br />movement throughout the Grand Valley but spent a major part of time in the <br />IS-mile reach. Two remained in the reach throughout the estimated spawning <br />period. <br /> <br />SDawnino Activity <br /> <br />A suspected prespawning aggregation of adult Colorado squawfish was observed <br />by Fishery Project personnel at river mile 178.3 in the IS-mile reach above <br />the Gunnison River confluence in mid-July 1982. In the first observation, <br />three radio-tagged fish were tracked to one riverine pool area, and nine <br />adults at or near spawning condition were then captured there after limited <br />net sampling efforts. The aggregation occurred a,few days after mean daily <br />water temperature had reached 20 'C and during a time when runoff flows were <br />dropping off sharply. A second aggregation was noted at river mile 175.3, <br />12 days after the initial observation. Drifting trammel nets through an area <br />