Rotenone.—Rotenone was used in pools of smaller streams, mouths of creeks, borrow-pits, and cut-off areas. Both powdered and emulsifiable rotenone were used. The rotenone was mixed with water and applied by hand, or into the backwash of an outboard motor.
Electric Shocker.—The electrical unit used in this study generated 115 volts and 600 to 700 watts, alternating current. The shocking unit consisted of two booms, each with two electrodes, mounted on and operated from a slowly moving boat. Fish were recovered in scape nets, or in many cases were identified as they lay stunned and were not collected.
Estimation of Relative Abundance
Data on relative abundance of fishes were obtained by counts of seine hauls at 29 of the 59 stations, counts of rotenoned fish at seven stations, and results with the electric shocker at nine stations. Counts were usually made in the field; however, in some collections all fish were preserved and counted in the laboratory. Some fish (or "swirls" presumed to be fish) observed while shocking were not identified and are not included in the calculations. However, all fish positively identified while shocking are included.
Age and Growth of Fishes
Fish from selected size-groups were aged in this study. Scales for age-determinations were removed from positions recommended by Lagler (1952:108). Scales were placed in water between glass slides and were read on a standard scale-projection device.
Pectoral spines of catfish were removed from one or both sides, sectioned, and read by methods described by Marzolf (1955:243-244).
Calculation of length at the last annulus for both scale-fish and catfish was made by direct proportion. All measurements are of total length to the nearest tenth of an inch unless specified otherwise.
Creel Census
From April 6 to May 28, 1957, a creel census was taken below Turtle Creek Dam. From June 16 to July 24, 1958, I periodically visited the main points of access to the Big Blue River, beginning approximately eight miles downstream from Tuttle Creek Dam and ending six miles upstream from the maximal extension of the reservoir at capacity level. Access-points consisted of 11 bridges, two power dams, and three areas where county roads approached the river. Eleven eight-hour days were spent in the 1957 census and 22 checks in 15 days were made in 1958. An equal number of morning (6:00 a.m. to 12:00 noon) and afternoon (12:00 noon to 8:30 p.m.) checks were made.