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increases the amount of inundated vegetation along shorelines. It is our feeling that flooded vegetation provides refuge for non-native fishes (non-native cyprinids and YOY /juvenile channel catfish) in Deso/Gray during periods of high flow. The channel narrowing and associated encroachment of vegetation have likely created a more stable environment during the spring peak. In comparison, the fish community in Westwater Canyon is dominated by native species. In Westwater Canyon, steep, sheer bedrock walls afford relatively little refuge during periods of high flows, which likely explains the depauperate non-native fish community found there (Chart and Lentsch 1998b). Biological Gila spp. RepYOduction and YOYHabitat Use In their intensive study of Gila spp. reproduction, Day et al. (Report B) found young of the year (YOY) chub mean CPUE was highest for the 1994 cohort (10.31/100 m3), second highest for the 1996 cohort (3.28) and lowest. for the 1995 cohort (0.31) (see Report B; Table 4). Captures of all native species were severely depressed in l 995. Chub captures in 1995 were only 2.5% of 1994; ranking fourth among the five native fishes. Chart and Lentsch (1998) reported their greatest catch of YOY chubs in August 1993, (14.73/100 m3; 23 habitats sampled between RK 343 - 236.7) prior to the start of the nursery habitat study. The greatest discrepancy between the concurrent UDWR fish surveys was the catch of YOY chubs in 1994. Whereas Day et al. reported their greatest catch that year, ,Chart and Lentsch only collected nine YOY averaging 19.3 mm TL in 56 seine hauls during the 28 June - 04 July monitoring trip (Report C; Table 1}, which ranked third highest of their five years reported. Day et al: also- reported their lowest within-year CPUE in July of 1994, nevertheless, the results are anomalous. The low CPUE reported is indicative of the risk involved with conducting a single annual trip to assess reproductive success (see Report C; recommendations). The results of the nursery habitat study provided insufficient information for rigorous analysis of the effect of annual peak river flows on YOY chub numbers with only three years of data. Comparison of these different regimes indicates differing chub response to these flows. The highest catch rates for chubs was in 1994. The peak flood that year occurred in the third week of May and was only 11,600 cfs at Green River, Utah. Summer base flows were achieved five weeks later. Water clarity was good all year and water temperatures were above 20°C by June 27. These conditions allowed an early spawn and excellent, long-term conditions for ' growth; as evidenced by YOY chub mean total length of 60.8 mm in September. Excellent growth (0.8 mm/day) was also reported for YOY chubs collected in Westwater Canyon on the Colorado River during the summer of 1994 (Chart and Lentsch 1998b). In 1995, spring peak flow was not achieved until the third week of June, and summer base flows were not attained until the second week of August. Water temperatures reached 21 °C by July 20, peaked at 24 ° C in August and dropped below 20 ° C again in September. Turbidity was also higher in 1995 than 1994. These conditions may have postponed chub spawning, interfered with larval drift and decreased growth and survivability. As a result, chub captures were low and mean growth was only 55.6% (33.8 mm TL) of that from 1994. The 1996 water year was somewhat of a mix between the two preceding years. Discharge approached 1995 levels. However, peak flow was achieved by 22 May and summer base flows were attained by late July. Water temperatures had reached 25 °C by 25 July. xi