Specimens from the Big Blue River Basin have an average of 47.4 scale-rows around the body (range 42-54).
Ictalurus melas (Rafinesque), black bullhead: Evermann and Cox (1896:387) as Ameiurus melas (Rafinesque); and Canfield and Wiebe (1931:5-7, 10) as "bullheads." Stations 2-S, 6-S, 7-G, 11-G, 16-G, 20-G, 22-G, 23-G, 24-G, 28-G, 35-M, 40-M, 51-M, 53-S, 55-M, 56-S, 57-M, and 58-G.
Black bullhead occurred in all habitats, but were less commonly taken in the Big Blue and Little Blue rivers than in other streams.
Ictalurus natalis (LeSueur), yellow bullhead. Stations 7-G, 9-G, 10-G, 11-G, 17-G, 18-G, 19-G, 34-M, 35-M, 36-M, 37-M, 40-M, 47-M, 48-M, 53-S, and 55-M.
The yellow bullhead inhabited the muddy-bottomed streams and the upland, gravelly creeks, usually occurring in the headwaters. I obtained only one I. natalis in the sandy Big Blue River.
Ictalurus punctatus (Rafinesque), channel catfish: Cragin (1885:107); Meek (1895:135); Evermann and Cox (1896:386); and Canfield and Wiebe (1931:6-7, 10) as "channel catfish." Stations 1-S, 2-S, 3-S, 4-S, 5-G, 6-S, 7-G, 8-S, 9-G, 11-G, 14-S, 15-S, 16-G, 18-G, 25-S, 27-G, 30-M, 35-M, 38-S, 39-S, 41-S, 42-S, 43-S, 44-S, 46-M, 50-S, 51-M, 52-S, 53-S, and 56-S.
Channel catfish were most common in the larger, sandy streams, but occurred in other kinds of streams. The ages and calculated total lengths at the last annulus for 40 channel catfish were: I, no fish; II, 7.3 (16); III, 10.6 (5); IV, 12.3 (5); V, 13.3 (6); VI, 15.5 (4); VII, 18.0 (3); and VIII, 21.9 (1). These lengths are slightly lower than averages reported by Finnell and Jenkins (1954:5) in Oklahoma impoundments.
The length-frequency distribution of 438 channel catfish, collected by rotenone on August 5 and 7, 1958, indicated that two age-groups were represented. Without examination of spines, I assigned 265 fish to age-group O (1.3 to 2.9 inches, average 2.5) and 173 fish to age-group I (3.1 to 5.8 inches, average 4.5). The average total length of age group I (4.5 inches) is only slightly higher than the total length at the first annulus reported as average for Oklahoma (4.0 inches, Finnell and Jenkins, loc. cit.). It seems unlikely that my yearling fish taken in August, 1958, would have reached the length at the second annulus recorded in my study of spines (7.3 inches) by the end of the 1958 growing season.
From 1952 to 1956, severe drought was prevalent in Kansas, probably causing streams to flow less than at any previously recorded time (Minckley and Cross, in press). This drought must have resulted in reduced populations of fishes in the streams. The channel catfish hatched in 1956 were therefore subjected to low competition for food and space when normal flow was resumed in 1957, and grew rapidly, reaching an average total length of 7.3 inches at the second annulus, while channel catfish that were members of the large 1957 and 1958 hatches suffered more competition and grew more slowly.
Noturus flavus Rafinesque, stonecat: Jennings (1942:365). Stations 3-S, 4-S, 6-S, 16-G, 25-S, 28-G, 38-S, 41-S, 42-S, 43-S, 52-S, 53-S, and 56-S.