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Considering these three experiments survival to the first year appears best for the 1994 cohort <br />and worst for the 1993 cohort. Density of Age 1 chubs were greatest in 1995 (21 fish / of hour) <br />despite relatively poor YOY production the previous year, i.e the 1994 cohort. However, with <br />only three cohorts to track through their first winter and spring runoff statistical comparisons are <br />not relevant. A matrix of contn'buting factors has been constructed to summarize the various <br />environmental conditions (Table 10) <br />Table 10. Matrix of environmental conditions contnbuting to Age 0 to Age 1 Gila spp. survival <br />in Westwater Canyon, Colorado River, Utah; 1992 - 1996. <br />F~ <br /> COHORTS <br /> 1992 1993 1994 <br />"~ TL'° Fap 44.6 39.5 45 <br />rd. Demity of YOY CH• Aled IIled lOW <br />~' ~h °f 1~vC Illed lOW Very hi <br />"'g "i°''~ °o"" 2967 ~ 4029 3006 <br />""` "ood"' •44300 13604 49300 <br />* . • Fall densities ofnon-native cyprinids relative to other years of study <br />** • Grand average of monthly mean flows for the winters (Nov. -Feb.) of 1992-93, <br />• 1993-94, and 1994-95. Flows recorded by the USGS at the Near CO-LJ?'State <br />•_ L»te gage. <br />*** ; first spring peak as recorded the State Line gage subsequent to spawn <br />The 1992 and 1994 cohorts were spawned in low flow years, while the 1993 cohort was spawned <br />in above average flows. As result, the densities of the respective cohorts and the size of <br />individuals varied greatly by late summer (Figure 9). YOY produced in 1992 and 1994 <br />averaged 45mm TL by mid to late August and recruited relatively well to the Age 1 cohort the <br />following summer. In coatrast, chubs produced in 1993, although moderately abundant, were <br />only 39.5 mm TL by September 7. Winter flows (Novemlier -February) were sigtufic~ntly <br />DRr1FT <br />• ~ 26 <br />