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<br /> <br /> <br />1 <br />C <br /> <br /> <br /> <br />1 <br />1 <br /> <br />L <br />1 <br /> <br /> <br /> <br /> <br /> <br />advantage of the positive aspects of both high and moderate flow scenarios, while avoiding <br />extremely low flows which favor nonnatives over the Colorado pikeminnow. <br />- Management of nonnative fishes will continue to be a problem. Although often suggested as <br />the best method of control, high spring flows did not appeaz to consistently negatively impact <br />nonnatives. Caze must be taken not to avoid managing exclusively for Colorado pikeminnow <br />to the detriment of other native fish or benefit of nonnative fish. <br />- Base flows (summer, fall): Maintain summer and fall flow levels below 140 m3/s (5000 cfs), <br />to maximize habitat availability. <br />- The maximum area of available nursery habitat may occur at discharges much lower or much <br />higher than the recommended base flow; the target summer dischazge should vary annually <br />and reflect changes in channel topography. <br />- Base flows (Winter): dischazges should be reduced. Current winter dischazges, increased by <br />Flaming Gorge Dam releases, overtop many low elevation bazs. <br />Changes to Standardized Monitoring Program <br />- No major changes to the ISMP sampling procedures are recommended. However, some <br />possible adjustments to the ISMP sampling aze presented: <br />1. Since higher turbidity was positively correlated with presence of Colorado pikeminnow, <br />and pikeminnow were commonly found in backwaters of less than 0.3 m depth, the <br />minimum depth requirement should be dropped to 0.2 - 0.25 m in turbid backwaters. <br />Turbidity can be visually assessed using the subjective scale used in reports B and C <br />without disturbing the fish community and biasing the sample. <br />2. The ISMP protocols call for fish community information to be taken from only one of <br />four seine hauls in each 5-mile subreach. This could be easily expanded to one seine <br />haul per backwater to provide more information on the fish community. This additional <br />data could help resolve remaining uncertainties regazding the effect of environmental <br />variables on nonnative fish densities, and fish community effects on Colorado <br />pikeminnow as well as other native fish. <br />- For depletion efforts, such as a nonnative cyprinid control program, a minimum of three <br />passes should be made in each habitat to ensure adequate fish removal. <br />- In order to link the ISMP catch rates with the total year class strength of Colorado <br />pikeminnow, population estimates should be done for several years on several selected <br />backwaters, using acapture-removal technique. <br />xx <br /> <br />