Laserfiche WebLink
Gila spp. Reproduction and YOYHabitat Use <br />• Day et al. (Report B) found young of the year (YOY) chub mean CPUE was highest for <br />the 1994 cohort (10.31/100 m3), second highest for the 1996- cohort (3.28) and lowest for <br />the 1995 cohort (.31) (see Report B; Table 4}. Captures of all native species were <br />severely depressed in 1995. Chart and Lentsch (1998) reported their greatest catch of <br />YOY chubs in August 1993, (14.73/100 m3; 23 habitats sampled between RK 343 - <br />236.7) <br />• Gila spp. reproduction was greatest during two extremely different flow years. In 1993, <br />the Green River peaked at 25,400 cfs on 31 May; flows exceeded 6,000 cfs for 68 days. <br />In 1994, flows peaked at 11,800 cfs on 21 May and flows exceeded 6,000 cfs for 34 days. <br />• In 1994, YOY chub grew best when average summer flows were lowest and main <br />channel temperatures were highest (1992-1996). Day et al. reported a mean total length <br />of 60.8 mm by September of that year. <br />Hatching date and corresponding Green River flow were calculated for several YOY <br />cohorts.: <br />• 1992 - 09 June @ 4900 cfs <br />• 1993 -June 21 @ 16,700 cfs <br />• 1994 - 07 June @ 10,000 cfs <br />• 1995 - 01 July @ 25,800 cfs <br />• Mean depth. of backwaters used by chubs was 0.59 m, almost exactly that reported by <br />Valdez acid Clemmer (1982). In addition to the greater depth, chubs in this study were <br />found in backwaters with greater length, width, surface area, and volume than in unused <br />backwaters. <br />Gila spp. recruitment <br />• Day et al. report that captures of age-1+ chubs were highest in 1994, i.e. greatest <br />recruitment of the 1993 YOY cohort. Similar results were reported by Chart and Lentsch <br />in their fish community monitoring data set. The 1994 cohort also recruited to the Age <br />1+ year class. <br />• Less abundant juvenile channel catfish (200-300 mm TL) and relatively high overwinter <br />flows of 3339 cfs (Std Dev - 493) were offered as partial explanation for better <br />overwinter survival in 1993 than 1994. <br />Colorado pikemi~anow reproduction, and YDYhabitat use <br />• Day et al. found Colorado pikeminnow to be the most abundant native species in samples <br />for both the 1995 (n=97) and 1996 (n=1729) cohorts. The 1994 cohort, represented by <br />435 fish, ranked third among native fishes that year. The very high catch for 1996 was <br />X1X <br />