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<br />. <br /> <br />. <br /> <br />IV. Study area (river miles, if appropriate): <br /> <br />Colorado River: RM 185 downstream to RM 0 <br /> <br />Two study reaches will be selected within Reach 1 of ISMP for YOY Colorado <br />squawfish and one study reach within Reach 2. Length of study reach will <br />be based on average number of backwater per river mile and may vary <br />between stations. <br /> <br />V. Study Methods/Approach: <br /> <br />Two reaches in the lower portion ISMP Reach 1 of the lower Colorado River <br />will be selected for intensive sampling. They will be sampled in July and <br />September at a minimum, further sampling dates may be added in subsequent <br />years based on preliminary results. Sampling will be coordinated with <br />standardized monitoring efforts so that duplication will not occur. All <br />backwaters and other quiet water areas within each station will be <br />sampled. <br /> <br />Video of the stations will be acquired 1 to 2 days prior to sampling and <br />computer images will be taken into the field for ground truthing and <br />identification of specific backwaters. This will be coordinated with the <br />Bureau of Reclamation so that flows do not change substantially between <br />acquiring the video and sampling. Backwaters will be seined to determine <br />whether or not squawfish are present and if so, how many. Physical and <br />biological habitat characteristics of each backwater will also be measured <br />in an attempt to distinguish habitats which are utilized from those which <br />are not. Reach characteristics, such as number or area of backwaters per <br />mile will also be identified as possible indexing factors for standardized <br />monitoring data. <br /> <br />Data will be collected over five field seasons. This is necessary because <br />of differences in the system from year to year and will also give us a <br />chance to refine the study design based on the preliminary data. Possible <br />nursery habitats other than traditional backwaters will also be sampled. <br />Seasonal degree-day accumulation will be measured in selected areas. Data <br />collected on physical and biological habitat characteristics will be <br />analyzed for possible relationships to use by squawfish. <br /> <br />Because considerably fewer Colorado squawfish are collected from the <br />Colorado River in Colorado than in Utah, studies in the upper river will <br />concentrate more on physical parameters than on biological parameters. <br />Seining will be limited to that conducted during fall standardized <br />monitoring and will encompass a larger area than in the lower river. <br />Relative abundance of non-native fish species (i.e. green sunfish, channel <br />catfish, red shiner, largemouth bass, carp, etc) will be evaluated in <br />greater detail than currently done under ISMP. The necessary field work <br />would be a joint effort between cooperating agencies to eliminate <br />duplication and meet mutual needs to evaluate Aspinall flow manipulations. <br /> <br />Detailed analysis of backwater development and maintenance in the upper <br />river will be accomplished by analyzing aerial photographs dating from <br />1937. Comprehensive measurement of main channel and backwater cross <br />sections will be made before and after runoff to document changes. <br /> <br />VI. Task Description (FY-1994): <br /> <br />Task 1: <br />Task 2: <br /> <br />Obtain video at each study reach, 3 times per year. <br />Sample all nursery habitat in each station for squawfish <br />utilization and ground truth videos. <br />Measure physical and biological habitat characteristics of low <br />velocity areas in each station. <br /> <br />Task 3: <br /> <br />19-C/page 2 <br />