Reproduction by black bullheads was limited in 1957, 1958, and 1959, and slight reduction in relative abundance occurred from 1957 to 1958. The relative abundance in 1959 remained nearly stable. If stream-flow remains essentially continuous for the next few years, the number of black bullheads probably will decline as individuals of the 1956 year-class reach the end of their life-span.
Reference has been made to the large hatch of channel catfish in 1957, in a discussion of that species. Conditions for survival of young channel catfish at the upper Neosho station in 1957 were good because there was continuous flow over many gravel-rubble riffles, which were largely unoccupied by other fish, in the spring and summer of 1957.
Table 12. Percentage-composition of the Fish-fauna at the Upper Neosho Station in 1957, 1958 and 1959, as Computed from Collections Obtained by Using Rotenone.
| Species | 1957 | 1958 | 1959 |
|---|---|---|---|
| Big-mouthed Buffalo............... | ........ | T[D] | T |
| Small-mouthed Buffalo............. | ........ | ....... | T |
| River Carpsucker.................. | T | 0.8 | 1.8 |
| Golden Redhorse................... | T | 3.0 | 5.7 |
| Creek Chub........................ | ........ | T | 0.8 |
| Red-finned Shiner................. | 1.3 | 3.0 | 0.8 |
| Red Shiner........................ | 6.5 | 13.1 | 12.1 |
| Ghost Shiner...................... | T | T | ........ |
| Blunt-nosed Minnow................ | T | T | T |
| Fat-headed Minnow................. | T | T | 1.4 |
| Stoneroller....................... | 0.8 | 1.5 | 3.5 |
| Black Bullhead.................... | 40.8 | 30.5 | 32.0 |
| Yellow Bullhead................... | 5.3 | 8.8 | 2.5 |
| Channel Catfish................... | 28.4 | 15.5 | 18.5 |
| Flathead.......................... | T | T | T |
| Stonecat.......................... | T | T | 1.4 |
| Spotted Bass...................... | T | T | 0.8 |
| Largemouth........................ | T | T | T |
| Green Sunfish..................... | 3.1 | 6.8 | 6.4 |
| Long-eared Sunfish................ | 8.8 | 3.7 | 1.9 |
| Orange-spotted Sunfish............ | 3.1 | 8.9 | 2.5 |
| Bluegill.......................... | T | T | T |
| White Crappie..................... | T | ....... | T |
| Logperch......................... | T | 2.1 | 0.8 |
| Slender-headed Darter............. | 0.6 | 0.6 | 3.1 |
| Orange-throated Darter............ | ........ | T | 2.5 |
| Total number of fish.............. | 786 | 965 | 513 |
| Size of sample-area in acre-feet.. | .002 | .33 | .33 |
Channel catfish also showed a slight decline in relative abundance after 1957, resulting from mortality in the 1957 year-class. With continuous flow, channel catfish will probably remain abundant, although annual reproductive success probably will be less than in 1957.
The big-mouthed buffalo, small-mouthed buffalo, creek chub and orange-throated darter were not taken in 1957, but appeared in collections in 1958. The river carpsucker, golden redhorse, red shiner, fat-headed minnow, stoneroller, stonecat, and slender-headed darter also increased in abundance between 1957 and 1959. The increased abundance of all these species in 1958 and 1959 resulted in a more diversified fauna, with lesser predominance by any single species, than in 1957 (Table 12); this change is related to the increased, permanent flow in 1958 and 1959.
Local Variability of the Fauna in Different Areas at the Upper Neosho Station, 1959
The shallow areas in which the shocker was used in 1959 are the prevalent habitat in the upper Neosho River. The relative abundance of fishes found in these areas is presented in Table 13. The red shiner was most abundant and was followed (in decreasing order) by long-eared sunfish, minnows of the genus Pimephales, green sunfish, red-finned shiner, channel catfish, and stoneroller. Other species combined comprise less than ten per cent of the population.
Table 13 also shows the variability in relative abundance of different species among areas that have the same general kind of habitat. The species composition is similar in all areas. The sample obtained with rotenone in 1959 is included in Table 13 to show differences in the fauna of deep, slowly flowing areas and shallower areas with stronger current. The differences in relative abundance indicate the kind of habitat that each species is able to utilize most fully.
Golden redhorse and black bullhead were most abundant in large, deep, quiet pools (5.7 per cent and 32 per cent of the total population) and were more abundant in Area 5 (3.2 per cent and 7.3 per cent respectively) than in any of the other shallow areas. Area 5 has greater average depth, more mud bottom, and less riffle area than areas 1, 3 and 6.