_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. Fishermen contacted were asked the following questions: home address (or residence at the time of the fishing trip); time they started fishing; kind of fish sought; number and kinds of fish in possession; and baits used. Also, the number of poles and type of fishing (from the bank, from boat, _etc._) were recorded. Fishes caught were examined to confirm identifications. About 80 per cent of all fishermen seen were contacted. Fish per man-hour, as used in this report, refers to the average number of fish of all species caught by one fisherman in one hour. Fisherman-day is the average time spent fishing in one day by one person. Because some fishermen used more than one pole, the data are also expressed as catch per pole-hour. COLLECTING STATIONS