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. D.,~ 1''''' ':i-(k( 1 . Once a fish was located, the boat was taken to the nearest shore or island, with care to not disturb the fish. From land, the RF-40 receiver was used exclusively; first to identify the fish by determining the frequency and pulse emi tted by the radiotransmi tter, and then to locate the fish us ing triangulation. Triangulating the location of a fish involved using the directional capabilities of the loop antenna to establish two or three bearings at different places along the shore. Each bearing was marked with two flagged metal rods driven into the ground 10 to 15 feet apart and in line with the sighting. . 3. 2 IUa'IDRI~ . Four types of monitoring were conducted during this investigation, 2-hour, 24-hour, crepuscular, and test flow monitoring. Two-hour monitoring was conducted on as many fish as possible during each field trip. The primary purpose for this type of monitoring was to locate each fish in the water and take physical measurements on habitat being used by the fish. Twenty-four hour monitoring was conducted only during year 1 to determine diel movements patterns and habitat use. Crepuscular monitoring was conducted only during year 2 to determine if behavior, movement, or habitat use were different during dawn and dusk. Test flow monitoring was conducted during flow release requests from Flaming Gorge Dam. The purpose for this type of monitoring was to assess fish movement during known changes in flow. . 3.2.1 Two-Hour Monitoring . Once a fish was contacted, its location was continuously monitored for 2 hours. During this time, movement and habitat utilized were recorded on radiotelemetry report forms provided by the FWS. Field maps of the river stretch occupied by the fish, including prominent features of the channel along with the location of the fish and movements, were illustrated on each report. At the end of the 2-hour monitoring period, habitat measurements were taken at sites used by the fish for a continuous periods of 15 minutes or longer. . . If a fish was moving upon initial contact, movements were followed and recorded for periods of up to 6 hours, depending on the effort expended to locate and reach a given fish. If the fish stopped moving, the procedure explained above was followed. If the fish continued to move, no measurements were taken. When possible, a fish was relocated later during the tracking trip in an attempt to record habitat used by the fish. 3.2.2 Twenty-four Hour Monitoring . Each fish during year 1 of this investigation was monitored for 24 hours. Twenty-four hour monitoring was usually begun by first completing a 2-hour moni toring procedure as described above. Following that, location and movements of the fish were checked and recorded at intervals generally not exceeding 2 hours. If a fish moved to a different location during the 24-hour period and remained stationary for a substantial time period, additional habitat measurements were taken at the new locations upon the completion of the . 9 .