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<br />oc... <br /> <br />and 2 adult razorbacks, and 7 young squawfish. The kettle worked <br />well in improving harvest efficiency. <br /> <br />V 1. study Area: <br />Old Charlie Wash (Green River RM 250) <br />VI I. study Methods/Approach: <br /> <br />Old Charlie will be dry prior to 1996 spring runoff. During runoff, <br />water will be allowed to fill Old Charlie through the inlet and <br />outlet water control structures. Water will be held at the site <br />only during runoff. Immediately after runoff, when the site becomes <br />disconnected from the main channel of the river (-July or August), <br />the site will be drained, and all fish will be harvested. Water <br />will not be held for an artificially extended duration. Fish <br />screens will be tested to see if they prevent all but the smallest <br />fishes from gettin9 into the site. If 1996 is a high flow year, <br />however, the river will overtop the banks, allowing fish of all <br />types and sizes into Old Charlie, and fish screens will not be <br />2/22/96 tested. In either case, a variety of gear types and sampling <br />strategies will be tested to determine relative vulnerability of <br />fish species and life stages, to support levee removal evaluation. <br /> <br />The following hypotheses will be tested during FY 96: <br /> <br />1. Floodplain depressions connected to the main channel of the <br />river will prOVide suitable nursery and/or growout habitat for <br />young razorbacks, and habitat for adult razorbacks. <br /> <br />2. Fish inlet/outlet control screens will prevent access by fishes <br />greater that three inches in length, but allow access by <br />larvae. <br /> <br />3. Production (plankton, benthos) is sufficient to sustain <br />razorback larvae over time. <br /> <br />4. Physical, chemical, and biological conditions are favorable for <br />sustaining razorbacks. <br /> <br />5. Old Charlie can be managed in a way that does not result in <br />increases of nonnative fishes in the main channel of the river. <br /> <br />6. Allowing Old Charlie to fill and drain naturally during spring <br />runoff will prevent bUild-up of nonnative fishes. <br /> <br />2/22/96 7. <br /> <br />Fish species/life stages are equally vulnerable to all gear <br />types/sampling strategies. <br /> <br />Finding razorbacks (and other endangered fishes) using Old Charlie, <br />(or trying to get in), and harvesting them during draining; and not <br />finding unusually large numbers of problematic nonnative fishes in <br /> <br />3 <br />