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Fish larger than 100 mm were weighed and measured individually. 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 one-third of the dorsal fin. Sampling Equipment No single technique efficiently sampled all habitats for all sizes and species of fish. Therefore, every attempt was made to use gear or combinations of gear that would provide a good cross-section of the fish population in each habitat. The effectiveness of electrofishing equipment is diminished substan- tially by the high conductivities and high turbidities encountered in the White River. However, a Coffelt variable voltage pulsator (VVP-15) unit was used since a pulsed DC current is reasonably effective under these conditions. The Coffelt unit employed a 4.0 kilowatt 220 volt _ generator as a power source. Conductivities fluctuated during the year and between some habitats, e.g., backwater and main channels, requiring frequent adjustment of the electrical equipment. Electrofishing gear was especially useful in collecting Colorado squawfish, a species which appeared to be more vulnerable to electrofishing than other species. Fishing effort was measured in hours. Trammel nets were predominantly set in the slow-flowing runs and in eddies. These nets were tended regularly at one to three-hour intervals depending upon temperatures and conditions. The trammel nets were 1 in (2.5 cm) and 1.5 in (3.8 cm) square mesh, 150 ft (45.75 m) long X 6 ft (1.83 m) deep, a wall of 10 to 12 in (25.4 cm to 30.4 cm) square mesh. Funnel type wire traps of 1 in (2.5 cm) chicken wire approximately 1.5 ft (0.45 m) diameter by 2.5 ft (0.77 m) long were set among large boulders or accumulations of debris. Effort fished was measured by the number of hours. Seines were the most utilized gear, and although a variety of seine sizes and meshes were used, one-quarter inch (6.35 mm) mesh nets were used predominantly. Seines were hung with double weighted lead lines so they would stay on the bottom in all anticipated current. The catch per effort was determined ?y dividing the number of fish captured in a given area by the area (m ) sampled. Compact, durable time efficient equipment was procured to collect physical and chemical data. This included a direct reading Marsh- McBirney (Model 201) portable water velocity meter. Water velocity measurements were taken at 0.6 distance from the substrate. Water depths were recorded with a collapsible stadia rod and a Lowrance (Model LRG 1510A) depth finder. Total dissolved solids, salinities and conduc- tivities were measured with a Yellow Springs meter (Model 33) with a combined conductivity and temperature probe. Conductivity was expressed as micromhos per centimeter. Salinity was temperature compensated and recorded in grams per kilogram. A Hach colorimeter (Model DR/1) was used to measure turbidity in formazin turbidity units (FTU). Dissolved oxygen readings were taken using a Hach Field Kit. 12.