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Relationship of flows and habitat to catch of Colorado pikeminnow and non-native cyprinids There was no linear correlation between flows and catch rates of Colorado pikeminnow. ~ The total catch per effort (CPE in #fish/100 m2) of Colorado pikeminnow in the summer and fall was maximized during the average flow year of 1996. The catch rates in the high and low flow years were much lower (Figure 8). The catch rates of Colorado pikeminnow at sampling flows were highest at moderate flows from 2000 to 4000 cfs (Figure 9). Since the peak flows are positively correlated with sampling flows, it is not surprising that catch rates would also be ~ maximized near average flows. Total habitat area did not appear to be related to catch rates of Colorado pikeminnow (Figure 10). Non-native cyprinids catch rates (CPE in #fish/100 mZ) followed similar patterns of relationship with flow and habitat as Colorado pikeminnow catch rates (Figure 11). Non-native cyprinid catch rates were maximized in the fall of 1996. However, aside from the extremely high ~ catch rate in fall 1996, non-native catch rates declined as the peak flow increased. Again, there was no lineaz relationship with catch rates and habitat area (Figure 12). Although non-native cyprinids are supposed to interact negatively with Colorado pikeminnow, there was actually a positive correlation between the catch rates ofnon-native cyprinids and Colorado pikeminnow. An interesting comparison between the Green River and Colorado River results can be ~ made here. The peak flow to habitat area relationships were similar, in that high peak flows were negatively correlated with total habitat azea and volume on both rivers. High peak flows were also negatively associated with fall non-native catch rates in both azea and volume (#fish/100 m2, and fish/100 m3 ). On both the Green and Colorado rivers, Colorado pikeminnow catch rates were maximized after average spring peaks. The very strong positive correlation between non- ~ native cyprinid catch rates and habitat volume seen on the Green River was non-existent on the Colorado River. The moderate negative association between high non-native catch rates and Colorado pikeminnow catch rates on the Green River, was moderately positive on the Colorado River (Table 13) . The conclusion drawn from the Green River data, that non-native cyprinids were limiting ~ the occuntence of Colorado pikeminnow YOY, and that habitat was only limited due to competition with the NNC, does not appear to be supported on the Colorado River. In general, the Colorado River had more total and quality habitat, more non-native cyprinids, and fewer pikeminnow than the Green River, but a positive correlation between non-native cyprinid and Colorado pikeminnow catch rates. Perhaps there maybe some differences of productivity between the rivers that would affect both Colorado pikeminnow and non-native cyprinids, but no data are contently available to test this, and the rivers are quite similar in sediment, gradient, and other physical characteristics. 16