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<br />c:;-y <br /> <br />VI. Study Methods/Approach <br /> <br />Removal of nonnative fishes and evaluating the use by native endangered <br />fish of riverside gravel pits, sloped toward the river that flood <br />during runoff and drain during the receding flow stage, will be <br />conducted for three years with the fourth year devoted for preparation <br />of a final report. One of the strategies suggested by Tyus and <br />Saunders (1996) that might be cost-effective and also be an immediate <br />means of reducing the abundance of nonnative fishes would be mechanical <br />removal. Multiple gear types such as trap and fyke nets, trammel nets, <br />seining, and electrofishing will be intensively used to collect fish. <br />Past and recent experience with sampling in riverside ponds has <br />revealed that species composition and size varies .among different gear <br />types used, Therefore, different sizes and several species of both <br />nonnative and native fishes are anticipated to be captured with the <br />aforementioned traditional gear types in the mouths of connection <br />channels and in the ponds. Both study goals and objectives will be <br />accomplished concurrently. 1hree years of field work are necessary to <br />evaluate both programs during spring streamflows over a range of water <br />years (i.e, low- vs. medium- vs. high-water years). Capitol funds will <br />be used for draining, back-filling, and sloping these ponds. <br /> <br />Trap and fyke nets will be run almost continually, whereas trammel nets <br />will be set only during daylight hours and will be checked about every <br />two hours. Electroflshing will be conducted at least once weekly in <br />each pond. Seining will be conducted in shallow-water areas where <br />other gear types are ineffective to target collecting small-sized <br />nonnative fish. As the pond drains in early summer, seining will <br />become the primary gear used to remove young-of-the year nonnative fish <br />produced. These gear types will be used from April through July. <br /> <br />Gardner (river mile 174.4) and Jarvis ponds. (river mile 171.0) have <br />been two ponds initially selected for this work. Gardner Pond will be. <br />back-filled and sloped following spring runoff in Fiscal Year 1997, <br />prior to the commencement of this study. Funds for the draining, back- <br />filling, and removal of nonnative fishes and ultimate reconnection of <br />this pond to the river will not be associated with the work plan to <br />remove nonnative fish by mechanical means which will start in spring <br />1998. Prior to the ponds being connected to the river, all nonnative <br />fish will be removed by draining the pond. If the pond cannot be <br />entirely drained to eliminate all nonnative fishes, chemical treatment <br />with chlorine will be applied to supplement draining to completely <br />eradicate all nonnative fishes. Additional sloped gravel pits will be <br />incorporated into the work plan if they become available. <br /> <br />Information recorded for each site will include the numbers, age <br />composition, and biomass of nonnative and native fishes collected and <br /> <br />8_ <br />