Laserfiche WebLink
Table 6. Densities ofnon-native cyprinids (NNC) at Westwater (WV~ and Moab (MO), and <br />Loma (from Anderson 1999). <br /> <br />YEAR Drift <br />NNC density <br />(total abundance) Drift <br />NNC density <br />(total abundance) <br /> Westwater Moab Loma <br />1992 113610 976200 597009 <br />1993 26294 4140555 64015 <br />1994 27461 3325758 512212 <br />1995 13494 965335 181363 <br />1996 151830 1055191 14683 <br />Relationship of larval abundance to fall year class strength <br />The relative abundance of juvenile Colorado pikeminnow in nursery habitats in the fall <br />may reflect the abundance of Colorado pikeminnow larvae in the drift. The abundance of <br />Colorado pikeminnow in the fall was evaluated by two concurrent studies. The Interagency <br />Standardized Monitoring Program (ISMP) samples age 0 Colorado pikeminnow in the fall by <br />seining two backwaters every five miles in two reaches of the Colorado River (USFWS 1987). <br />Reach one, from RK 0 (confluence of the Green and Colorado rivers) to RK 177, brackets the <br />Moab site. Reach two, above the Westwater site, encompasses RK 271.9, to RK 223.6, from the <br />confluence of the Colorado and Gunnison rivers downstream to Mee Canyon. The other <br />concurrent study was part of the Aspinall study plan, and evaluated the effect of flows on nursery <br />habitat and juvenile Colorado pikeminnow abundance by seining and measuring all nursery <br />habitats within two 16 km reaches of the Colorado River below Moab (Trammell and Chart, <br />1998), which was within the ISMP reach one. Fall catch rates in #fish/100 mZ from ISMP reach <br />1, and the combined nursery habitat reaches were highly correlated (r2 = 0.93, p = .02) for the <br />five years of this study (Table 7). <br />12 <br />