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0 0 <br />factors influencing squawfish movements will be characterized with respect to physical <br />habitat conditions, season, and spawning. Published reports and the UCRB centralized <br />database will be used to compile relevant raw data. Correlations between occurrence of <br />threshold flow periods and subsequent patterns in the above population parameters will <br />be used as the first indicator of potential cause - effect relationships. <br />Modde and Smith (1995) examined movements of 13 radiotagged squawfish from <br />data provided in Wick et a. 1983 and Wick and Hawkins (1989), and determined <br />movement through the Maybell Diversion occurred at flows less than 200 cfs and <br />movement occurred through both Cross Mountain Canyon and the Maybell diversion at <br />flows of 200 -350 cfs. They indicated they could not determine if squawfish movement <br />at these sites was inhibited at lower flows. This radiotelemetry data for Yampa River <br />fish will be re- examined after threshold flow levels, their frequency and duration are <br />established to assess 1) a characteristic range of flows and time periods for annual return <br />migrations from spawning, and if available, 2) movement, distribution, and migrational <br />activity prior to, during and after the low -flow occurrence. Distribution of Carlin and <br />PIT tagged squawfish will also be examined for distribution and movement patterns <br />associated with these threshold flow periods. <br />Phase II <br />Objective 3. <br />This evaluation will be initiated when the threshold low -flow conditions are <br />projected to occur in late summer. Analyses performed in Objective 2 will provide <br />historic flow data characterizing the average flow conditions in spring and early summer <br />that lead up to the threshold low -flow conditions determined in Objective 1. Monitoring <br />daily flows at the USGS Maybell gage will determine if flow conditions are likely to <br />meet study criteria, and if so, initiate field sampling preparations. Three approaches are <br />considered for evaluating passage. <br />The primary approach will be to collect and implant up to 10 adult Colorado <br />squawfish in the Juniper reach of the Yampa River (RM 104 -90) with emphasis on <br />obtaining fish above the Patrick Sweeney diversion at RM 98. This is desirable under <br />the assumption that these fish will return to the Juniper reach following spawning and be <br />required to pass all three of the potential passage barriers identified here. These fish <br />would be collected and implanted in March - April, prior to downstream migration and <br />during rising water levels that facilitate boat use, electrofishing, and scare and snare <br />techniques in suitable habitat. Concerns exist for adverse modification of fish behavior <br />prior to migration, including inhibiting an individual fish from migrating or lack of <br />individual fitness and physiological fitness to accomplish a round trip spawning <br />migration, but results from Irving and Modde (1994) indicate recently - implanted <br />squawfish adults from the White River annually accomplished more extensive round -trip <br />migrations than would be experienced by upper Yampa squawfish. Once implanted with <br />12 -18 month radiotags, these fish would be monitored weekly for initiation of <br />downstream migration into Yampa Canyon. <br />5 <br />