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Table 5. Pearson Correlation coefficients /associated probabilities for YOY chub CPEs vs a variety of flow and temperature parameters metrics (see Table 1 for descriptions). Catch rates are from two sub-reaches(above and within Westwater Canyon) during the months of July and August, 1992 -1996. ~~'`R'"~'~ ABOVE JULY ABOVE - AIIG CANY -JULY CANY - AUG STPK -.53 / .47 .38 / .52 -.56 / .32 -.06 / .91 STPKPRE .98 / .016 .14 / .82 .97 / .004 .721.17 CISPK -.56 / .43 .41 / .49 -.587 / .30 -.10 / .87 PRPKFLO -.56 / .43 .15 / /81 -.57 / .31 -.18 ! .77 POSKFLO -.45 / .54 .45 / .45 -.49 / .40 -.OS / .93 PREPKIO .22 / .77 -.71 / .17 :22 / .72 -.25 / .67 POSPK20 .73 / .27 .04 / .94 .75 / .14 .19 / .76 CISMAYDEV -.681 / .383 -.004 / .99 -.17 / .78 -.58 / /31 CISJUNDEV .25 / .74 -.% / .008 .07 / .90 -.47 / .42 Three significant correlations were found. There was a strong positive correlation found when July YOY chub catch rates (both above and within the canyon) were regressed against the previous years instantaneous peak runoff. By August, the effect of the previous year's flows had apparently diminished, but still explain a considerable portion of the variability in canyon catch rates (R~.72). The other significant correlation resulted when YOY chub catch rates upstream of Westwater Canyon were regressed against the absolute amount the observed June monthly mean deviated from the historic mean (24000cfs). In other words the closer the observed June monthly mean flows were to the historic June monthly mean flow the greater our catch of YOY chubs in August, above the canyon. Similar, but not significant, relationships were found when using August canyon catch rates and when looking at a similar flow analyses incorporating May montlily averages. The simpke relationship between flow and chub reproductive success, as indexed by catch rate, does not appear to be linear (Figure 'n. In this graphical representation it appears that on the average chub reproductive success is optimized when the Colorado River peaks near 30000 cfs as they did in 1996. Flows much less than this and flows much greater are likely outside the optimum flow window. DRAFT . . 15