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split between August (n=812) and September (n=915) samples. The 1993 monitoring trip was delayed until late August due to high flows and resulted in the collection of 203 YOY pikeminnow YOY -the greatest CPUE recorded during monitoring trips. Monitoring efforts were scheduled to coincide with the presence of spawning pikeminnow in Deso/Gray. As a result, those efforts were often conducted too early to adequately assess pikeminnow reproductive success. Back calculated spawning dates of the 1993 cohort indicate the bulk of that years spawn occurred on or near 17 July 1993 when Green River flows were 4,360 cfs: • The results of both fish studies (Reports B and C) indicate the greatest recruitment of YOY pikeminnow occurred when Green River flows peaked near 25,000 cfs (in 1993 and } ,, ~~-; 1996; see table 1 above). The 1996 cohort of pikeminnow was likely most abundant. } "~ That year Green River spring and summer flows exceeded 6,000 cfs for the greatest period of time (90 days). The majority of these >6,000 cfs flow days occurred early in the hydrograph with the river peaking on 22 May 1996 and dropping below 6000 cfs by ~ 07 July. Colorado pikeminnow in Desolation and Gray canyons primarily used secondary channel type backwaters. Recruitment of the YOYpikemin~aow to Age 1+ Monitoring efforts for juvenile and adult fishes indicated the 1993 and 1994 pikeminnow cohorts recruited to Age 1+ better than the 1992 or 1995 cohorts. Evaluating recruitment of the abundant 1996 cohort was beyond the scope of this study. Neither study measuring YOY pikeminnow abundance in Deso/Gray reported a particularly strong cohort in 1994. However, Day et al. observed excellent growth of the 1994 cohort increasing from a mean total length of 24.9 mm in July to 57.7 mm by September. Fish Cofnmu~zity Monitoring: urge bodied fish All nine recaptured chubs were collected at their original capture location. • Long term monitoring trammel net catch rates suggest the number of adult sized chubs in Desolation declined as result of the poor recruitment prior to 1993. Catch rates were lowest in 1996. In 1989, the length frequency analysis indicates the presence of a relatively weak 1988 year class, a stronger 1987 year class, and evidence of strong recruitment from the years prior to 1986. The 1993 year class appears to have recruited to a juvenile size in the most substantial numbers since that time. ~; ~'~ xx