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capacity for the reach can be expected. Aggressive, introduced carp and channel catfish may become concentrated in low-velocity eddies and pools; this might explain displacement of squawfish into runs. In the 15-mi1e reach, squawfish have two options in dealing with low summer flow conditions. One method is to `hole up' in portions of slow runs that remain relatively deep due to springtime scouring of the bed and the presence of a downstream control structure such as a submerged cobble bar. At such times the fish are concentrated in these sites and are not free to utilize the resources of the entire river. The strategy is to wait out the low-water period until higher flows return. The second strategy is for the fish to travel downstream and wait out the low-flow period in reaches below the confluence with the Gunnison River where more water is available. Though our sample is small, we have some evidence to indicate that adult squawfish may indeed leave the 15-mile reach when water becomes low. During 1986 we maintained contact with three squawfish from May through December. All three spent the year within the reach (one briefly left during the spawning season and returned in July). Mean monthly flows during August, September and October in 1986 were 2,040, 1,868 and 2,223 cfs, respectively. During 1987, mean flows were somewhat lower: 1,214 cfs in August, 812 cfs in September and 733 cfs in October. We maintained contact with 5 squawfish during 1987. Three remained in the reach year-round (one left and returned in July), one left and returned by October 9 prior to the end of the irrigation season, and one left and returned on November 9 shortly after the irrigation season ended and more water was returned to the reach. Mean flows were lowest in 1988: 588 cfs in August, 542 cfs in September and 178 in October. Contact was maintained with two squawfish; both left the reach after the spawning period was over and did not return that year. One left in late September or early October; the other left in late July or early August. Such displacements from the home range are no doubt stressful for fish and strongly suggest a seasonal reduction in carrying capacity for the reach - this in a river where quality adult habitat is already much reduced in miles. During our 1986-1988 radiotelemetry study, squawfish experienced a range of summer flow levels. The months of August, September and October of 1986 and August of 1987 had moderate-flows comparable to historic (1902-1942) summer flow levels (see Osmundson and Kaeding 1991). September and October of 1987 and 1988 and August of 1988 had flows slightly lower than the mean flows of recent (1954-1989) summer months. All summer flows today are approximately 1,600 cfs lower than they would be under virgin conditions because of water diverted immediately upstream by local irrigation companies. These withdrawals predate the historic period. Thus, without alterations, a summer day with a flow of 500 cfs, for example, would be more than 2,100 cfs under normal conditions. Tyus (1992) warned against determining instream flow needs of fish based on fish habitat use data collected under altered, suboptimal and perhaps unsuitable habitat conditions. Resulting recom- mendations will likely provide a minimum amount of water needed for fish survival rather than a more favorable amount needed to promote population recovery. Data from the 1986-1988 study indicated that during low-water conditions some squawfish left the 15-mile reach and those that stayed displayed a distinct change in habitat selection. We interpret such behavioral changes as reflective of suboptimal conditions. Our view is that squawfish habitat use data collected from the 15-mile reach during abnormally low-water conditions may demonstrate the ability of the species to modify its habitat use patterns to enable it to temporarily cope with adverse conditions, but it is not 32