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YOY Colorado pikeminnow collected during fall sampling trips of the concurrent nursery habitat and ISMP studies, were positively correlated to the number of days of growth between average hatch date and date of fall sampling (rz = 0.55). Days of growth for all years ranged from 50 to 98 based on the average hatch date. There was also a positive correlation between total length and the DD accumulations for the same period (rz = 0.63). Although these correlations did not appear to be statistically significant (p > 0.2), a biological relationship exists. In the high flow year of 1995, the degree day accumulation was low, resulting from a shorter period of accumulation as well as lower average water temperatures. Thus, the average total lengths of pikeminnow in the summer and fall of 1995 were 12 and 31 mm, respectively, which were small in comparison to the average for all five yeazs of 20 and 38 mm (Figure 13). Overwinter survival, based on the percent change in catch rates between fall and spring sampling, was also positively correlated to the total lengths of Colorado pikeminnow in the fall (rz = 0.97) (Trammell and Chart, 1998). The lowest overwinter survival was seen for the smallest fish, in 1995, while the highest survival was seen in 1994, the year with the highest total length in the fall. The smaller size of Colorado pikeminnow in 1995 may have resulted in reduced survival of the age 0 Colorado pikeminnow through prolonged vulnerability to predators. Red shiner have been observed to contain larval fish in their stomachs (Muth and Ruppert 1996). Although no larval pikeminnow were positively identified in red shiner stomachs, it is likely some predation occurs, due to the overlap in habitat use (Trammell and Chart 1998). Other larger fish predators such as channel catfish are also present in nursery habitats, and likely have some impact although no larval pikeminnow predation has been documented. The flows and temperatures may also have affected the productivity of habitats and food availability for Colorado pikeminnow, and other species, with less productivity occurring in high flow years (Bestgen 1996). Non-native cyprinids are thought to have a negative effect on Colorado pikeminnow survival through competition (Muth and Snyder 1995). In 1995, summer and fall NNC catch rates were the lowest of the five years (Figure 14) (Trammell and Chart, 1998). Despite relatively low catch rates of NNCs, there were still over 2000 collected for every Colorado pikeminnow in the fall sampling. At low population levels, non-native cyprinids are probably still a significant source of competition. In contrast to 1995, the moderate flow yeaz of 1996 had the highest juvenile Colorado pikeminnow abundance in the fall, although total larval abundance was nearly identical to that in 1995 at Moab. The highest abundance ofnon-native cyprinids was also seen in the fall of 1996, although drift densities were only moderate. This suggests that some combination of flow and temperature variables resulted in increased productivity in 1996, which benefitted both taxa. However, factors contributing to the success of Colorado pikeminnow recruitment in 1996 were not as easily distinguished as factors contributing to the demise of recruitment in 1995. 14