(3) Temporal variations occur in populations at the same station. There were both seasonal and diurnal differences in relative numbers of species taken in these collections. This was noted especially at station C-5 where collecting was done both at night and by day. Spawning by certain species during the course of the study complicated estimates of their relative abundance.
(4) In tabulating percentages of fishes obtained an arbitrary element is often unavoidable in deciding whether a station, especially a station on a tributary, should be considered as part of the lower, middle, or upper segment of a river system.
Despite these disadvantages it is felt that table 6 has factual basis permitting some reliable interpretation.
Table 6.—Relative Abundance in Per Cent of Fishes in Collections From Three Stream Segments.
| Big Caney River | Grouse Creek | |||||
|---|---|---|---|---|---|---|
| Lower | Middle | Upper | Lower | Middle | Upper | |
| L. osseus | .7 | .5 | .6 | .02 | ||
| D. cepedianum | .3 | .02 | ||||
| Carpiodes carpio | .06 | 1.0 | ||||
| I. bubalus | .6 | .45 | 1.4 | |||
| I. cyprinella | .1 | |||||
| I. niger | .01 | |||||
| M. erythrurum | .2 | 1.1 | 1.0 | .03 | .5 | 1.1 |
| M. melanops | .1 | .01 | .1 | |||
| Cyprinus carpio | .7 | 1.3 | .2 | |||
| C. anomalum | .6 | 5.9 | 18.0 | .1 | ||
| N. boops | .6 | .6 | 5.1 | 1.3 | ||
| N. buchanani | .01 | |||||
| N. camurus | 6.4 | 5.5 | .4 | |||
| N. lutrensis | 8.8 | 1.0 | .5 | 6.4 | 11.4 | 15.2 |
| N. percobromus | 1.1 | |||||
| N. rubellus | .4 | 1.4 | 3.9 | |||
| N. umbratilis | 17.6 | 28.3 | 15.4 | 2.5 | 3.9 | 5.5 |
| N. volucellus | .3 | .4 | .3 | |||
| P. mirabilis | .3 | |||||
| P. notatus | 3.5 | 5.7 | 13.0 | .9 | 6.6 | |
| P. vigilax | .8 | |||||
| P. promelas | 2.9 | |||||
| P. tenellus | .7 | .5 | .01 | |||
| G. affinis | 14.6 | .4 | .4 | 20.8 | 10.2 | 1.0 |
| F. notatus | .1 | 6.6 | 17.2 | 1.4 | ||
| I. melas | .9 | 2.2 | 2.4 | 5.6 | 2.3 | 18.0 |
| I. natalis | .5 | .5 | .8 | |||
| P. olivaris | .01 | .01 | ||||
| I. punctatus | .3 | .4 | ||||
| E. spectabile | 1.9 | 4.9 | 18.0 | .4 | .3 | .3 |
| P. copelandi | .8 | .1 | .01 | |||
| P. phoxocephala | .1 | .1 | ||||
| P. caprodes | .4 | .6 | .2 | .2 | .2 | .4 |
| M. salmoides | .06 | 1.1 | .3 | |||
| M. punctulatus | .5 | 1.7 | .4 | |||
| P. annularis | 3.9 | .8 | 2.9 | 4.2 | .3 | |
| L. cyanellus | 3.4 | .8 | 6.6 | 5.2 | 1.8 | 30.5 |
| L. humilis | 10.6 | 13.1 | 1.8 | 31.4 | 17.7 | 14.8 |
| L. megalotis | 12.4 | 22.3 | 12.0 | 3.6 | 14.0 | 1.7 |
| L. macrochirus | .3 | .2 | 1.3 | |||
| A. grunniens | .1 | |||||
| L. sicculus | 7.1 | 1.6 | .4 | 7.7 | 10.2 | |
Big Caney River
The "lower segment" of Big Caney River is immediately upstream from Hulah Reservoir, and is not the lowermost portion of the entire river basin, but merely the lower part of the river in the area studied. A conspicuous characteristic of the lower segment was the general restriction of the deep-bodied suckers and the carp to this part of the stream. Other fishes that were most common in the lower section were Pimephales vigilax, Percina phoxocephala, Gambusia affinis, and Aplodinotus grunniens. Labidesthes sicculus and Lepisosteus osseus ranged into the middle section of the stream, but were present in larger numbers downstream. Ictalurus punctatus, Pomoxis annularis, and Lepomis macrochirus were taken chiefly in downstream habitats; however, stocking has confused the distributional pattern of these species. Notropis lutrensis, although found throughout the system, progressively declined in numbers taken in the middle and upper sections. Approximately 18 species were usually taken in downstream collections.
No species were found exclusively in the middle section of the Big Caney system. Micropterus punctulatus, Notropis umbratilis, and Lepomis megalotis tended to be most common in the middle section of the main stream. These three species were taken together at stations C-5, C-6, C-8, and C-10.
The upper section yielded no species that did not occur also in another section. Fishes most abundant in the upper section included: Campostoma anomalum, Etheostoma spectabile, Notropis boops, Notropis rubellus, Pimephales notatus, and Lepomis cyanellus. Ictalurus natalis also seemed more common upstream than in lower parts of the basin.