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. . MATERIALS AND METHODS . Equipment Description A boom equipped 18-ft (5.5-m) flatbottom boat was used to electrofish the river reaches. Power was supplied by a Honda ES4500 generator producing 220 volts and 4.0 kilowatts. A Coffelt Model 15 variable voltage pulsator (VVP) was used to produce a pulsating direct current. Trammel nets 150 ft (45.8 m) long and 6 ft (1.8 m) deep were used to fish eddies and low velocity runs. The nets were composed of I-in (2.5-cm) and 1.5-in (3.8-cm) square mesh with a wall of. 10- to 12-in (25.4- to 30.4-cm) square mesh. A seine 30 ft (9.1 m) long by 4 ft (1.2 m) deep, and having 0.25-in (6.4-mm) mesh was used to sample shallow water areas. Double weighted lead lines were used for sampling areas with high water velocity. Water velocity measurements were taken with a direct reading Marsh-McBirney (Model 201) portable electro-magnetic current meter. Corresponding water depths were measured with a calibrated wading rod. Specific conductance of the water was measured with a Beckman Solu Bridge RB3 meter. Dissolved oxygen and pH levels were measured with a Hach field chemistry kit. Radio transmitters implanted in selected Colorado squawfish were AVM fish modules (AVM 1979) weighing approximately 11 g and Smith-Root modules weighing approximately 15 g. Transmitters were powered by a . . . . . . . 6 .