Temporal Variability of Fauna in the Same Areas

The variability of the population in successive collections from the same area is presented in Table 14. Supplementary data obtained in Areas 2, 4 and 7 support conclusions discussed below for Areas 1, 3 and 6. The abundance of some species maintained a constant level, whereas that of others varied.

Table 14. Numbers of Individuals Collected by Means of the Shocker at Varying Intervals in September, 1959. The Number at the Top of Each Column is the Date When the Collection was Made.

Species	Area 1			Area 3			Area 6
Species	3	4	8	9	10	15	16	18	20
Golden Redhorse	2	2	...	5	5	2	...	...	3
Creek Chub	4	3	7	1	...	...	1	2	...
Sucker-mouthed Minnow	...	...	...	54	42	25	31	7	6
Red-finned Shiner	...	...	1	...	...	4	31	13	4
Red Shiner	44	7	211	117	170	438	186	209	62
Blunt-nosed Minnow	...	...	...	4	10	19	108	91	13
Fat-headed Minnow	1	...	...	1	2	3	112	156	48
Stoneroller	67	39	49	84	107	55	54	67	22
Black Bullhead	5	...	1	2	1	...	...	3	7
Yellow Bullhead	1	1	...	2	1	...	1	...	3
Channel Catfish	14	7	...	36	16	...	3	1	23
Channel Catfish(yy)[H]	23	16	17	34	34	22	40	23	28
Flathead	...	...	...	4	8	1	2	...	1
Flathead(yy)	4	1	1	2	1	1	...	...	...
Stonecat	25	8	12	7	7	5	...	...	...
Green Sunfish	27	17	12	13	16	17	62	62	74
Long-eared Sunfish	13	12	1	6	3	3	10	22	31
Logperch	1	...	...	2	...	...	...	...	...
Slender-headed Darter	...	1	2	55	45	23	15	1	1
Orange-throated Darter	2	1	2	9	11	8	5	...	1
Total	233	115	316	438	480	626	661	657	347

Stoneroller, channel catfish (young-of-the-year), green sunfish, and long-eared sunfish formed the most stable element of the population, in that the numbers of these species varied less in successive collections than did numbers of other species.

The number of orange-throated darters remained constant at Areas 1 and 3, and the number of stonecats changed little in successive collections from Area 3. I suspect that an apparent decline in stonecats at Area 1 on September 4 was due to a slow rate of dispersal from the point of release (see pages 413, 414).

Some species (sucker-mouthed minnow, red-finned shiner, slender-headed darter, and fat-headed minnow) decreased significantly in successive samples from the same area because of mortality in handling or movement out of the area of initial capture.

The decrease in abundance of the sucker-mouthed minnow may have been due to some mobility of the species. Evidence for mortality caused by handling was obtained for the red-finned shiner and probably accounts for the reduction of this species in Area 6. The red-finned shiner is also probably a mobile species. The reduction in abundance of the slender-headed darter seems unexplainable because no evidence was obtained for either movement or mortality.

Fat-headed minnows also declined markedly in successive collections from Area 6, the only area in which the species was common. No marked fat-headed minnows were taken outside the area of release, indicating low mobility of the species. I cannot certainly account for their decline; possibly there was latent mortality due to shocking.

The numbers of red shiners, blunt-nosed minnows, and juvenile channel catfish varied erratically in successive collections, probably as a result of movement. This problem is discussed for all species in a later section.