Laserfiche WebLink
Nonnative cyprinids (red shiner, sand shiner, fathead <br />minnow, and redside shiner) also are affected by flow <br />manipulations. Osmundson and Kaeding (1989) noted a marked <br />increase in the abundance of red shiner, fathead minnow, and sand <br />shiner during a 3-year study in the Grand Valley (Loma and <br />Palisade) during which spring peak and summer flows progressively. <br />declined. McAda and Kaeding (1989a) found that the more common <br />nonnative cyprinids in the upper Colorado River (Green River <br />confluence to Grand Junction) were in greatest abundance in <br />summers following low spring flows and were in lowest densities <br />during periods following high spring flows. In the Yampa River, <br />1980-1984, Muth and Nesler (1993) found that earlier initiation <br />of spawning and higher catch-per-unit-effort (CPUE) for nonnative <br />cyprinids, and longer spawning seasons for red shiner, sand <br />shiner, and fathead minnow were generally associated with low <br />peak discharge and low-moderate daily mean and total discharges. <br />Conversely, later initiation of spawning and lower CPUE for <br />nonnative cyprinids, and shorter spawning seasons for red shiner, <br />sand shiner, and fathead minnow were associated with high peak <br />discharge and moderate-high daily mean and total discharges. <br />Correlative evidence between discharge and cyprinid abundance <br />suggests that high flows flush nonnative cyprinids from their <br />preferred lentic habitats, resulting in local reductions in their <br />abundance and reproductive success (Valdez 1990). <br />Physicochemical control of fish species through water level <br />manipulations in reservoirs has been successful. Various fishes, <br />30