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fathead minnow and sand shiner were fairly stable. In the Colorado River, CPE for fathead minnow and red shiner peaked in the middle portion of the sampling period and then declined. However, catch rates for both species remained higher in later years (considerably so in Reach 1) than when the monitoring program began in 1986. CPE for sand shiner increased steadily in both Colorado reaches between 1986 and 1992. These three introduced species occupy the same habitat used by YOY Colorado squawfish. All backwaters (in which all fish were counted) in the Colorado River that contained Colorado squawfish also contained red shiners (Table B-15). Red shiners were found in most of the seine hauls containing Colorado squawfish in the Green River as well (range, 75 to 100%; mean, 94%). Fathead minnows were found in 80 to 100% (mean, 98%) of samples with Colorado squawfish in the Colorado River and in 27 to 100% (mean, 85%) in the Green River. Sand shiners occurred in 67 to 100% (mean, 909'0) of the samples containing Colorado squawfish in the Colorado River and 0 to 73% (mean, 37%) of those samples in the Green River (Table B-15). These species were found in backwaters with Colorado squawfish at about the same rate they were found in all backwaters sampled (in which all fish were counted), which suggests that Colorado squawfish are not avoiding backwaters utilized by these species. Gmean CPE for Colorado squawfish was significantly correlated with CPE for fathead minnow in five cases (Reach 1, 1987 [r=.73]; Reach 3 in 1987 [r=.89], 1988 [r=.68], and 1990 [r=.75]; and Reach 4 in 1991 (r=.53]), with CPE for red shiner in three cases (Reach 3 in 1987 [r=.76] and 1992 [r=-.70]; and Reach 4 in 1986 [r=.68]), and with CPE for sand shiner in two cases (Reach 1 in 1990 [r=.56] and reach 4 in 1986 [r=.60]; Table B-16). The non-significant correlations were all very low, but about 70% were positive values. Discussion Distribution and Abundance The distribution patterns of YOY Colorado squawfish correspond to observations made by earlier investigators in the Green (Tyus and Haines 1991) and Colorado rivers (Valdez et al. 1982; Archer et al. 1985; McAda and Kaeding 1989a). Tyus and Haines (1991) summarized catch-rate information for 1979 through 1988 (excluding 1986) collected from the Green River using a similar sampling design; however, they sampled the entire Green River and divided it into seven strata. Their strata A and B correspond to Reach 3 of ISMP and strata E and F correspond to Reach 4. They reported a higher catch rate in the lower Green River (corresponding to Reach 3) in 6 of the 9 years of study. During ISMP, CPE was higher in Reach 3 than in Reach 4 during 6 of 7 years. Two years (1987 and 1988) sampled by Tyus and Haines overlapped with the second and third years of ISMP and data collected by the two programs followed the same patterns: catch rates in both studies were much higher in 1988 than they were in 1987 and CPE was higher in Reach 3 than in Reach 4 during both years. The similar pattern in relative abundance of the two studies suggests that the sampling design is able to pick up important differences in relative abundance among years or reaches. Between 1982 and 1988, mean CPE in 1988 was the second highest value observed by Tyus and Haines (1991). The highest value they observed occurred in their equivalent of Reach 3 in 1980 and in Reach 4 during 1979. The lowest CPE values observed were in 1983 and 1984 when abundance of small Colorado squawfish was lower than observed during all 7 years of ISMP. Their low values contrasted with apparent high production of larvae in the Yampa River (Nester et al. 1988; where 19