Laserfiche WebLink
<br />of age-0 squawfish in this reach was greater than in Reach 3 of the Green River in both fall (34 mm TL) and <br />spring (43 mm TL). Fish from the Green River were usually larger in both fall and spring (Personal <br />communications with M. Moretti, UDWR, April 1987), because water temperatures were generally higher than <br />in the Colorado River. <br />Two juveniles were captured in this reach in fall 1987, and one was captured in spring 1988 (Table 7). No <br />CPE statistics were computed considering the small numbers of fish involved. Juveniles caught in fall ranged <br />from 71 to 112 mm TL, while the fish captured in spring was 80 mm TL. <br />3.3.2 1988 Year Class <br />Total numbers and CPE of the 1988 year class showed increases over the winter. From fall 1988 to spring <br />1989, total numbers increased from 89 to 186, and CPE increased from 2.64 to 4.92/100 m2. This magnitude <br />of increase can be explained by immigration of age-0 from upstream regions. Average change in length for <br />these fish from fall to spring was from 42 to 45 mm TL. <br />As in the Green River, several seine hauls were taken along the shoreline, off the mouths of backwaters to <br />determine if any numbers of age-0 Colorado squawfish were occupying other habitats. No squawfish were <br />found in such efforts. It was noted that the Colorado River was slightly warmer than the Green River, and <br />that backwaters sampled were 1 to 9°C warmer than the main channel. <br />The number of juvenile Colorado squawfish was also high in the Colorado River, as previously discussed for <br />the Green River. The numbers decreased from 36 to 24 juveniles from fall 1988 to spring 1989. These fish <br />ranged in length from 61 to 99 mm TL in fall and from 71 to 116 mm TL in spring, and were all considered <br />from the 1987 year class. <br />3.3.3 1989 Year Class <br />Total numbers and CPE of the 1989 year class showed a decrease over the winter. From fall 1989 to spring <br />1990, total numbers decreased by 88% from 120 to 14. CPE decreased by 78% from 2.07 to 0.42/100 m2. <br />Fish captured in fall 1989 averaged 40 mm TL and ranged from 24 to 67 mm TL. Age-0 Colorado squawfish <br />captured in spring 1990 averaged 41 mm TL with a range of 29-54 mm TL. Average ovetwinter growth of the <br />1989 year class was 1 mm. ~ <br />Seven juveniles were captured in fall 1989 and one was captured in spring 1990. These fish ranged in length <br />from 70 to 124 mm TL in fall, and the one fish in spring was 77 mm TL. These juveniles were considered to <br />belong to 1988 year class. <br />3.3.4 1990 Year Class <br />Total numbers and CPE of the 1990 year class decreased from fall to spring in the lower 50 miles of Reach <br />1. From fall 1990 to spring 1991, total numbers decreased by 83% from 111 to 19, and CPE decreased by 78% <br />from 2.86 to 0.63/100 m2. <br />Fish captured in fall 1990 averaged 44 mm TL and ranged from 27 to 60 mm TIw Age-0 Colorado squawfish <br />captured in spring 1991 averaged 46 mm TL with a range of 32 to 62 mm TL. Average overwinter growth of <br />the 1990 year class was 2 mm. <br />Thirteen juvenile Colorado squawfish, ranging from 63 to 154 mm Tlw were captured in fall 1990. <br />One juvenile Colorado squawfish, 70 mm TL, was captured in spring 1991. <br />8 <br /> <br />1 <br />1 <br /> <br />1 <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br />