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. . III. Study Goals, Objectives, End Product A. Goal: Develop biologically defensible, seasonal flow recommendations for the maintenance and enhancement of habitat in reaches of the upper Colorado River important to the recovery and delisting of the rare Colorado River fishes (River Mile 0-185). B. Objectives: 1. Estimate relative abundance of age-l Colorado squawfish in spring. 2. Estimate relative abundance of larval Colorado squawfish and sympatric species in summer. 3. Estimate relative abundance of sympatric species in fall. 4. Identify possible relations between the relative abundance of important species and various environmental variables. IV. Study Area Colorado River, RH 0-185 V. Study Methods/Approach Spring sampling will be conducted as described for the fall Standardized Interagency Monitoring Program. Sampling will be done in the lower 45 miles of reach 1 of the Colorado River. Riverwide larval sampling will be conducted for two months during the period when larval Colorado squawfish are available. Samples will be taken with dip nets along quiet shoreline and backwater areas. From river mile 155 to 185, samples will be taken every week at two mile intervals. Samples will be taken every two weeks at five mile intervals in the rest of the river. Data on sympatric species additional to that required by the monitoring program will be collected during fall monitoring in the Colorado river. Data on environmental variables will be collected at the time of fish sampling, and will also be available from USGS and other sources. VI. Task Description (FY-1994) 1. Conduct spring sampling to estimate relative abundance of age-l Colorado squawfish. 2. Conduct riverwide larval sampling during the time when larval Colorado squawfish are estimated to be available. Aspinall-DjPage 2