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Table 8. Seasonal drift densities for Loma, Westwater and Moab and coefficient of determination (RZ) between the three sites, and summer fall and spring densities of Colorado pikenunnow YOY in backwaters and the RZ between drift and backwater densities. YEAR DRIFT DRIFT DRIFT SUMMER FALL SPRING LOMA WW MOAB Mean Mean Mean #/1000 M' #/1000 M' #/1000 M3 #/100 M' #/100 M' #/100 M3 1992 6.6 1.1 8.8 17.9 14.2 4.7 1993 3.6 2.5 11.5 3.2 8.6 0.87 1994 3 0.53 1.08 3.8 1.1 2.5 1995 12.9 1.46 41.7 0.07 1.0 0.10 1996 2.4 1.64 22.6 78.0 37.6 No Data LOMA RZ - 0.0022 0.5712 0.2049 0.2285 VW1l RZ - - 0.0815 0.0087 0.0559 MOAB R2 - - - 0.0094 0.0022 SUMMRZ - - - - 0.9521 Drift and back water density ofnon-native cyprinids Examination ofnon-native cyprinid (fathead minnow, red shiner and sand shiner) abundance has relevance to this study in two arenas. First non-native cyprinids (NNC) spend the majority of their life cycle in backwater habitats. There is likely a positive ecological relationship between NNC abundance and habitat and nutrient availability, so their abundance in a given year is likely an indicator of resource abundance. Secondly, since Colorado pikeminnow utilize the same habitats as NNC in the summer and fall, competition occurs when resources (habitat and nutrients) are limiting. Therefore trends in NNC density maybe useful for explaining trends in Colorado pikeminnow YOY densities from backwater habitats. As with Colorado pikeminnow, drift densities ofnon-native cyprinids were not linearly con elated with either peak flows or between stations. Loma drift density was the most closely related to peak flow (rz = -0.76). It was also the most closely related to fall abundance of non- native cyprinids in backwaters (rz= 0.88). Westwater drift density was lower than the other two stations, and Moab had the highest and most variable drift density. Neither Westwater nor Moab drift densities were related to fall abundance (Table 9). A very strong relationship was found between spring runoff flows and density of non- native cyprinids in the fall for the four year period, 1992 to 1995. The two highest runoff years (1993 and 1995) had the lowest NNC densities in habitats sampled in the following summer, fall and spring (pre-runoff] collections (Table 10). Mean NNC density was three times higher in summer and fall samples in the two low runoff years (1992 and 1994) than the two high years (1993 and 1995) (Table 10). The low year NNC density averaged six times greater in the (spring) pre-runoff samples. These data suggest that NNC density is higher in low flow years, probably due to extended and improved conditions for growth, reproduction and survival. If average NNC density estimates are a good indicator of annual productivity potential, then in general it appears that low flow years had better potential than high flow years. However, 1996 the intermediate flow year, had double the NNC density in the fall surveys than the two low flow years (Table 10). The fact that the best year for NNC productivity occurred in the intermediate 17