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Each habitat present in a station was sampled with every effective gear type. Rare fish captures were located on river maps to the nearest 0.1 mi (0.16 km), water depth and velocity measurements and the predominant substrate types were recorded. All fish collections were accompanied with detailed information regarding location, date, time of day, measure of effort, habitat type, substrate type, and a series of depth and velocity measurements to describe the range of conditions present in the ,sample area. The 2.5 mi (4 km) reach below each station was sampled by elec- trofishing in order to provide a survey of adult fishes and to collect rare fishes. Physical data were also collected at sites where rare fish ti were captured. Fish larger than 100 mm were individually weighed and measured. Large samples of smaller fish were sorted into 10 mm groups and counted. All rare fishes greater than 200 mm total length were tagged with a Carlin dangler tag attached through the dorsal musculature at the point immediately below the posterior 1/3 of the dorsal fin. Samtling Equipment No single technique efficiently sampled all habitats for all sizes and species of fish. Every attempt was made to use gear or combinations of gear that would provide a good cross-section of the fish population to each habitat. Flectrofishing gear was especially useful in collecting Colorado rquawfish and it appeared that this species was more vulnerable to electrofishing than other species. Conditions in the Yampa River proved good for electrofishing success and two units were employed: white water sections were fished with a Coffelt VVP-2C, and the Yampa River above Deerlodge Park, RIM 45 (km 72), was fished with a Coffelt VVP-15. Trammel nets were predominantly set in slow-flowing runs and eddies, and checked regularly at one/two and three-hour intervals depending upon temperature and conditions. Trammel nets were 1 in and 1.5 in square mesh, 150 ft long x 6 ft deep with a wall of 10 to 12 in mesh. The gear most utilized was the seine. While a variety of seine sizes and meshes were used, 1/4-in mesh nets were used predominantly. Seines were hung with double-weighted lead lines so they would stay on the bottom in current. Effort was measured by the area sampled i.e., length of seine multiplied by the distance pulled. 12