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Table 3.-Correlation (Pearson Correlation Coefficient), by sampling reach, of geometric-mean CPE for YOY Colorado squawfish during fall ISMP sampling with seasonal flow events at the nearest USGS gaging station, 1986-1992. Flow Highest Mean of 30 During Mean- Days Around Mean-Monthly River Flow River/ Sample Daily Highest Daily Reach Period Flow Flo„rr Apr May Jun Jul Aug Sep Colorado 1 .90° .66 .75' S8 .60 .88" .90° .56 .ST 2 .83° .91° .93' .93' .92' .88° .94° .90° .89° Green 3 .OS .23 .15 .31 .23 .17 .11 .15 -.09 4 .14 .57 .47 .22 .45 .50 .35 .23 .08 °Significant at P<.OS rates than the lower portion of the reach in 1986, but the mid to lower portion of the reach had higher CPE in 1987 and 1988. Gmean CPE was fairly even through the reach in 1989-1992. Although gmean CPE was reported here, total CPE exhibited the same trends by ISMP sampling reaches and by 10-mile subreaches (Figures B-1-B-3; Tables B4-B6). Interpretation of ISMP results using total CPE would not be different than already reported for gmean CPE. Growth Mean total length of Colorado squawfish collected at the end of their first growing season differed among the years and reaches sampled (Figures 6 and B-4; Tables B-7-B-9). Mean length was typically shorter in Reach 2 than in the other reaches except for 1982. Mean total length was typically between about 35 and 45 mm in reaches 1, 3, and 4 during most years. Mean total length (within reaches) was less than 30 mm in all reaches in 1986 and was the smallest observed during the 7-year study in all reaches, except in Reach 2 during 1990 when one 19-mm fish was collected. This was the highest runoff year observed during ISMP. The high runoff delayed warming of the water and the subsequent spawning period, giving the young fish a shorter growing season during their first summer of life. Mean total length was significantly correlated with accumulated temperature units in reaches 1, 3 and 4, but not in Reach 2 (Table 4). Because of missing temperatures, correlations of data from Reach 2 included only 1 year when more than one Colorado squawfish was collected. One of these fish was considerably larger than average at this time of year and another was considerably smaller. Mean total length of Colorado squawfish in reaches 1 and 2 was negatively correlated with river flows from the previous spring (Table 5). However, there was no similar significant correlation for reaches 3 and 4. This suggests a more direct interaction between spring flows and the subsequent warming of the river in the Colorado River than in the Green River. 12