Fish Populations, Following a Drought, in the Neosho and Marais des Cygnes Rivers of Kansas Part 8

Area 5 has a length of 250 feet, an average width of 50 feet, and a maximum depth of two and one-half feet. This is a shallow, quiet pool over rubble and bedrock bottom except for a small area of mud bottom (backwater) above the point where a short riffle drains into this pool from Area 6 (Pl. 30, Fig. 1).

Area 6 has a length of 200 feet, an average width of 50 feet, and a maximum depth of one and one-half feet. This is a shallow, quiet pool over bedrock bottom, except for a small area of mud bottom at one side of the upper end of the pool. A short, steep, rubble-riffle is included in this area at the upstream end (Pl. 30, Fig. 2).

Areas 2, 4, and 7 resemble at least one of the areas described above but were sampled less intensively. Data from areas 2, 4, and 7 are included in discussion of the total fauna of the upper Neosho river but are excluded from the discussion of representative parts of that fauna.

Methods

_Rotenone_

Rotenone was applied to an intermittent pool in 1957. In 1958 and 1959 rotenone was applied to the upper end of a pool and mixed by agitating the water. The concentration in the pool was maintained by slowly introducing part of the rotenone into the riffle at the head of the pool. This was the most effective means of obtaining a large sample of fish from the deeper, slowly flowing water of the upper Neosho. Pools in which rotenone was used had areas of as much as one-half acre and depths in excess of six feet.

_Shocker_

In 1959 the shocker was used extensively in several areas of the upper Neosho. Because of the small size of the stream, "tennis-racket"

electrodes were used effectively by two men--one carrying the electrodes and one picking up fish and placing them in a live-box. In fast water, many fish floated into a seine placed across the lower end of the area.

A large segment of the population was collected in this manner. Areas in which fish were collected by means of the shocker included riffles, and pools having flowing water no more than three feet in maximum depth. The bottom-type was usually gravel, rubble or bedrock, but a small amount of mud bottom was present in many pools.

Because of the necessity of wading, we could not use the shocker effectively in water more than three feet deep. In addition, turbidity of the water prevented effective collection of stunned fish in the deeper pools. Therefore, rotenone was more effective in deep water than was the shocker. In shallow, swift riffles and pools, the shocker yielded more reliable samples than did rotenone, because of difficulty in maintaining adequate concentrations of rotenone where flow was swift.

The relative abundance of each species in the upper Neosho was calculated from c.u.mulative results obtained by use of the shocker in seven areas in 1959. Population estimates were made by collecting fish with the shocker, marking them by clipping fins or staining them in Bismark Brown Y at a concentration of 1:20,000 (Deacon, 1961), returning them to the stream, and making a second collection three hours (Areas 1 and 3) or 24 hours (Area 6) later. The same area was shocked again within two to eight days. Collections throughout the one-half-mile section yielded information on movement.

Changes in the Fauna at the Upper Neosho Station, 1957 Through 1959.

The following discussion is based princ.i.p.ally on collections made with rotenone in 1957, 1958 and 1959 (Table 12). Other supplementary data aid in understanding the changes that occurred after the resumption of normal flow at the upper Neosho station.

The population in 1957 was strongly dominated by black bullhead and young-of-the-year channel catfish. Other common species were long-eared sunfish, red s.h.i.+ner, yellow bullhead, orange-spotted sunfish and green sunfish. This fauna, with the exception of young-of-the-year individuals, was a fauna produced during the years of drought. Deacon and Metcalf (1961:318-321) found a similar fauna in streams of the Wakarusa River Basin that had been seriously affected by drought.

The black bullheads taken in 1957 were predominately yearlings. It is likely that by 1956 the total fish population in the upper Neosho had been decimated by drought. The ponded conditions prevalent in that year were conducive to production and survival of young black bullheads. Fig.

3 shows that this dominant 1956 year-cla.s.s reached an average length of approximately 6.5 inches by August, 1959.

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-cla.s.s 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 s.h.i.+ner................. 1.3 3.0 0.8 Red s.h.i.+ner........................ 6.5 13.1 12.1 Ghost s.h.i.+ner...................... 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 Ba.s.s...................... 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 c.r.a.ppie..................... 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 ----------------------------------+--------+-------+--------

[D] T denotes less than one-half of one per cent of the population.

Channel catfish also showed a slight decline in relative abundance after 1957, resulting from mortality in the 1957 year-cla.s.s. 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 s.h.i.+ner, 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 s.h.i.+ner was most abundant and was followed (in decreasing order) by long-eared sunfish, minnows of the genus _Pimephales_, green sunfish, red-finned s.h.i.+ner, 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.

The golden redhorse and black bullhead have specific habitat preferences that are not evident in the above discussion. My collections indicate that the golden redhorse prefers deep water having some current, whereas the black bullhead prefers little or no current.

Species that prevailed in or near riffles were: creek chub, sucker-mouthed minnow, stoneroller, channel catfish (young-of-the-year only), flathead (young-of-the-year only), stonecat, slender-headed darter, and orange-throated darter. Of these species, the sucker-mouthed minnow, slender-headed darter and orange-throated darter reached their greatest abundance at Area 3, where the riffle is shallow, slow, and has a bottom composed of flat limestone rubble.

The riffle at Area 1 is, for the most part, deeper and faster than at Area 3 and has a bottom composed of gravel and small rocks. The creek chub, stoneroller, channel catfish (young-of-the-year), flathead (young-of-the-year), and stonecat reached their greatest abundance in Area 1. All species that showed a preference for riffles were rare or absent in Area 5 where no riffle-habitat was sampled. The riffle-dwelling species that were present in collections made with rotenone in the deeper pools were taken from the riffle into which rotenone was introduced.

The river carpsucker, blunt-nosed minnow, fat-headed minnow, channel catfish (yearlings and two-year-olds), flathead (yearlings and two-year-olds), green sunfish and long-eared sunfish showed a preference for shallow, quiet water. All of these species were more common in collections from Areas 5 and 6 than in collections from other areas.

TABLE 13. RELATIVE ABUNDANCE OF FISH (PER CENT OF TOTAL POPULATION MADE UP BY EACH SPECIES), IN THE FIRST COLLECTION MADE IN EACH OF FOUR DIFFERENT SHALLOW AREAS BY MEANS OF THE SHOCKER, IS SHOWN IN VERTICAL COLUMNS 1-4. RESULTS OF THE USE OF ROTENONE IN A FIFTH, DEEPER AREA ARE SHOWN IN COLUMN 5. COLUMN 6 COMBINES DATA FROM ALL COLLECTIONS MADE BY USING THE SHOCKER IN SEVEN SHALLOW AREAS (INCLUDING COLUMNS 1-4).

====================================================================== Area Area Area Area All 1 3 5 6 Rotenone areas ------------------------+------+------+------+------+----------+------ Big-mouthed Buffalo .... .... T[E] .... T T Small-mouthed Buffalo .... .... .6 .... T T River Carpsucker .... T 10.6 T 1.8 .8 River Carpsucker (yy)[F] .... .8 T 3.7 .... 1.0 Short-headed Redhorse .... .... .6 .... .... T Golden Redhorse .8 1.0 3.2 .... 5.7 T Carp .... .... .... .... .... T Golden s.h.i.+ner .... .... .... .... .... T Creek Chub 1.6 T T T .8 T Sucker-mouthed Minnow .... 11.2 T 3.4 .... 1.4 Red-finned s.h.i.+ner .... .... .... 4.0 .8 8.1 Red s.h.i.+ner 18.2 24.0 7.8 20.1 12.1 35.9 Sand s.h.i.+ner .... 5.2 .... 1.1 .... T Pimephales (yy) .... .... .... .... .... 6.7 Mountain Minnow .... .... .... T .... T Blunt-nosed Minnow .... .8 4.1 11.7 T 3.4 Parrot Minnow .... .... .... .... .... T Fat-headed Minnow T T 3.4 12.1 1.4 2.6 Stoneroller 27.7 17.4 .6 5.8 3.5 5.1 Black Bullhead 2.1 T 7.3 T 32.0 .6 Yellow Bullhead T T .... T 2.5 T Channel Catfish (j)[G] 5.8 7.6 41.3 T 14.6 4.2 Channel Catfish (yy) 9.5 7.0 T 4.3 3.9 2.5 Flathead (j) .... .8 2.1 T T T Flathead (yy) 1.6 T .... .... .... T Stonecat 10.3 1.4 .... .... 1.4 .7 Spotted Ba.s.s .... T .6 T .8 T Largemouth .... .... T .... T T Green Sunfish 11.2 3.5 5.9 12.2 6.4 10.1 Long-eared Sunfish 5.4 6.0 5.1 14.6 1.9 12.8 Orange-spotted Sunfish T T 1.4 1.8 2.5 .5 Bluegill .... .... 1.0 .... T T White c.r.a.ppie .... .... .... .... T T Logperch T T T T .8 T Slender-headed Darter T 11.4 1.1 1.6 3.1 1.3 Orange-throated Darter .8 1.8 T .5 2.5 T Freshwater Drum .... .... T .... .... T Total number of fish 242 484 727 924 513 17,796 Area in square feet 840 6324 12500 10000 .... ....

Volume .... .... .... .... 1/3 acre-foot ------------------------+------+------+------+------+----------+------

[E] "T" designates species that comprised less than 0.5 per cent of the population.

[F] (yy) signifies young-of-the-year.

[G] (j) signifies yearlings or two-year-olds.

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.

====================================================================== 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 s.h.i.+ner ... ... 1 ... ... 4 31 13 4 Red s.h.i.+ner 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 ----------------+-----+-----+-----+-----+-----+-----+-----+-----+-----

[H] (yy) means young-of-the-year only.

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 s.h.i.+ner, 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 s.h.i.+ner and probably accounts for the reduction of this species in Area 6. The red-finned s.h.i.+ner 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.