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<br />sampling efforts in Black Rocks between August and early October. <br />Capture as many adult-size chubs as possible using a variety of gears, but <br />especially trammel nets and electrofishing. Set four trammel nets in mid- to <br />late afternoon and run them every 2 hours until late evening. Conduct <br />shoreline electrofishing through out the entire Black Rocks area at least one <br />evening during every sampling trip. Set hoop or tyke nets at appropriate <br />locations. Measure to total length (H 1 mm) and weigh (H 20 g) all chubs <br />and Colorado squawfish captured. PIT tag all Colorado squawfish and <br />chubs greater than 160 mm total length. Identify, measure to total length, <br />and count all sympatric fishes collected during all sampling efforts. Sample <br />for YOY chubs by seining in shallow shoreline areas and by electrofishing at <br />night in deeper areas and along rock walls. <br /> <br />Attempt a population estimate for humpback chubs within Black Rocks using <br />models suitable for the sampling methods used. Population trends and <br />population size structure will be determined using standard techniques. <br />Standard catch-per-effort (CPUE) values will be calculated for all species <br />captured and all gears utilized. <br /> <br />Techniques may be modified after 1998 because it is not known whether the <br />sampling effort described above will be adequate to recapture enough <br />. chubs for a reliable population estimate. Intensive sampling will be <br />conducted for 3 years in a row to conduct the population estimate. Intensive <br />sampling (three 4-day sampling trips) for a population estimate will be <br />repeated 5 years after the third intensive sampling year. This sampling <br />design will produce an interval of 8 years between midpoints of the two <br />population estimates. Less intensive sampling (one 4-day sampling trip) will <br />be conducted during intervening years. Annual hump~ack chub monitoring <br />will continue until the Interagency Standardized Monitoring Program is <br />modified or terminated. <br /> <br />8. Conduct expanded sampling for a mark-recapture population estimate of <br />subadult and adult Colorado squawfish in the Colorado River (expanded <br />program for FY-98). <br /> <br />The Monitoring Work Group decided that annual. shoreline electrofishing <br />provides a useful estimate of relative abundance on a basin-wide basis with <br />a relatively small expenditure of effort. However, they felt that it should be <br />supplemented on a regular basis with a more intensive mark-recapture <br />population estimate and size structure evaluation. The extra effort will <br />provide addition data to track changes in population size and structure that <br />can not be evaluated under the current program. The last strong year <br /> <br />4 <br />