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1.2 .. N •~ w o a- .4 U~ c '~ ~ j U ~ .4 N ~~ .3 O p N ~- ~ p .2 ~ .1 U 0 Reach 1 - 86 87 88 89 90 91 92 Reach 2 86 87 88 89 90 91 92 Year 6 4 2 0 1.2 .8 .4 0 Reach 4 86 87 88 89 90 91 92 Year Figure 3.-Geometric-mean CPE (Colorado squawfish per 10 mZ seined) for the four reaches sampled during fall, YOY Colorado squawfish monitoring, 1986-1992. Bars represent ± 1 SE. Gmean CPE of YOY Colorado squawfish was positively correlated with the flow regime of the previous spring and summer for the two Colorado River reaches but not for the two Green River reaches (Table 3). Reach 1 had lower r values than did Reach 2 and also had fewer significant correlations. Catch rates in Reach 2 had the strongest relationships with parameters describing spring flow. Although catch rates in Reach 1 wefe positively correlated with spring flows, the strongest relationships were with late spring-early summer flows and with early fall flows. When catch-rates were summarized by 10-mile intervals within the ISMP reaches, shifts in distribution of YOY Colorado squawfish within reaches became evident (Figures 4 and 5; Tables B-5 and B~). Areas of highest CPE within reaches varied among years. Reach 1 of the Colorado River showed the most variation among years, with highest CPE in the mid to upper portions of the reach in 1986 through 1991, and highest CPE in the lower part of the reach in 1989 and 1990 (Figure 4). The upper part of Reach 1 has had very few YOY Colorado squawfish in recent years, but YOY squawfish wece found there in moderate numbers during 1986 and in earlier collections (Archer et al. 1985). The upper section of Reach 4 contained more YOY Colorado squawfish than the lower section in 1986 and 1987, but the situation was reversed in 1988 and 1991 (Figure 5). Catch rates were fairly uniform throughout the reach in 1989, 1990, and 1992. Upper Reach 3 had considerably higher catch 9 86 87 88 89 90 91 92