Fish Populations, Following a Drought, in the Neosho and Marais des Cygnes Rivers of Kansas Part 5

The 1958 and 1959 year-cla.s.ses were much less abundant than were the 1957 young. Therefore, it seems likely that the growth of the 1957 young in the Neosho River was depressed because of crowding. The 1959 year-cla.s.s was larger than the small 1958 year-cla.s.s, thus conforming to a general expectation that strong year-cla.s.ses will be followed by weak year-cla.s.ses.

Reproduction by channel catfish in 1957 seemed greater in the Neosho River than in the Marais des Cygnes River (Table 10); this coincided with a greater change in volume of flow in the Neosho River than in the Marais des Cygnes River (Tables 1-4). The 1957 year-cla.s.s seemed more crowded, and grew more slowly, in the Neosho than in the Marais des Cygnes River.

#Ictalurus natalis# (LeSueur)

Yellow Bullhead

Yellow bullhead were taken only at the middle station on the Marais des Cygnes and upper station on the Neosho. The yellow bullhead is more restricted to streams than is the black bullhead. Both species decreased in abundance during a period of continuous flow (1957 to 1959) following drought at the upper Neosho station. Collections in 1958-'59 indicated an increase in average size. Of four individuals marked and released at the upper Neosho station in 1959, one was recaptured about three hours after being released. It had not moved from the area of release.

#Ictalurus melas# (Rafinesque)

Black Bullhead

The black bullhead was abundant at the upper stations on each river, especially in backwaters having mud-bottom. The species was not taken in the mainstream of the lower and middle Neosho stations, but was taken at the middle Neosho station in a pond that is often flooded by the river.

Although the fish was common or abundant in nearly all pools at the upper Neosho station, it was most abundant in one pool that had a bottom predominately of mud.

At the middle Marais des Cygnes station, 109 individuals were collected and fin-clipped on 8, 9 and 24 July 1957. Three of the 19 marked on 8 July were recaptured in the same area on 9 July. The area was poisoned on 13 September, 1957, and 130 black bullhead were taken, none of which had been marked.

In 1959, 96 black bullhead were taken at the upper Neosho station (five in Area 1 and 91 at the White Farm). In these collections, 25 were marked (fin-clipped or dyed) and six were recaptured. Four of the six had not left the area of capture one and two days after being released.

The fifth fish recaptured was one of five individuals that had been displaced one pool downstream. When recaptured seven days later, this fish had moved upstream over two steep riffles (two to three inches deep, 75 feet and 166 feet long) past the site of original capture to the next pool. The sixth fish, marked at the same time but returned to the original pool, was recaptured nine days after original capture and had moved upstream over a long riffle (two to three inches deep, 166 feet long) and a short riffle into the second pool above the original site of its capture.

Rotenone was applied to a small (.04 acre-feet) backwater ditch having a soft mud bottom at the upper Marais des Cygnes station on 25 July, 1957; 1526 black bullhead, one green sunfish and one white c.r.a.ppie were collected. A sample of 60 bullhead averaged 4.6 inches T.L. (range 3.5 to 6.6 inches) and 540 individuals averaged .7 ounce each. These fish probably represented the 1956 year-cla.s.s.

The upper Neosho station had a large population of black bullhead, strongly dominated by fish less than four inches T. L. (range 1.5 to 3.8 inches), in the spring of 1957. Most were approximately two inches T.

L. and probably represented the 1956 year-cla.s.s. Growth, according to length-frequency, following restoration of stream-flow, shows a regular increase in length of this dominant 1956 year-cla.s.s (Fig. 3). A scarcity of young, especially in 1958 and 1959, is apparent in Fig. 3. This may be due to the fact that a strong year-cla.s.s usually is followed by one or several weak year-cla.s.ses. However, it more probably reflects the fact that black bullhead are characteristically pond fish, and as such are not so well adapted to reproduction in flowing streams as are many other species. Metcalf (1959) found this species most abundantly in the intermittent headwaters of Walnut River and Grouse Creek in Cowley County, Kansas.

[Ill.u.s.tration: FIG. 3. Length-frequency of black bullhead at the upper Neosho station, 1957, 1958 and 1959.]

#Pylodictis olivaris# (Rafinesque)

Flat-headed Catfish

The flathead is the largest sport-fish occurring in Kansas. Several weighing more than 40 pounds are caught from streams each year, and the species reportedly attains sizes in excess of one hundred pounds.

Several aspects of the biology of the flathead in Kansas have been discussed by Minckley and Deacon (1959).

The abundance of flathead declined slightly from 1957 through 1959, counting fish of all sizes. This trend is attributable to a large hatch in 1957; the 1957 year-cla.s.s strongly dominated the population throughout my study. Natural mortality in that year-cla.s.s was compensated by increased average size of the individuals (to six inches in autumn, 1958, and 11 inches in autumn, 1959).

The numbers of flathead caught at the upper stations on the Neosho and Marais des Cygnes rivers differed from the general trend in that the species was rare in 1957 and increased slightly by 1959. Flathead are most numerous in large streams, and in the drought they probably were almost extirpated from the headwaters. After 1957, continuous flow and increased volume of flow were accompanied by a gradual increase in numbers of flathead in the upstream parts of the two rivers. The species was most abundant at the middle and lower Neosho stations, where 10.5 per cent of all fish shocked in 1957 and 1958 were _P. olivaris_.

The habitat of the flathead varied with size of the individuals.

Young-of-the-year inhabited swift riffles having rubble bottom; individuals four to 12 inches in total length were distributed throughout the stream; those more than 12 inches in total length were most commonly in pools in a.s.sociation with cover (rocks, or drifts of fallen timber).

Male flathead mature at 15 to 18 inches total length, females at 18 to 20 inches. The sp.a.w.ning season in 1959 probably began in early June and extended to mid-July. I attempted to find sp.a.w.ning fish on 19 June and for one month thereafter. On 19 June nine holes were dug into a 75-yard section of a clay bank adjacent to a long, shallow, rubble riffle.

A flathead was first found in one of these holes on 22 June, and others were frequently found in this and one other hole until mid-July.

Although channel catfish were often found in nearby holes, that species was never present in the two holes used by flatheads. The holes occupied by flathead (as well as those used by channel catfish) characteristically had silt-free gravel bottoms and a ridge of clean gravel across the entrance.

A nest containing a flathead and eggs was located on 11 July. In checking the hole I first put my foot into the entrance, then slowly advanced my hand into the hole, feeling along the bottom with my fingers until they entered the open mouth of a large catfish. I backed off slowly and then felt beneath the fish. The fish was directly above the egg-ma.s.s, seemingly touching the eggs with its belly. As I touched the front of the egg-ma.s.s the fish struck viciously, taking my entire fist into its mouth. It continued striking until I removed my hand from the hole after obtaining a small sample of eggs, which proved to be in an early stage of development (no vascularization evident).

When the nest was checked again on 13 July the eggs and fish were gone.

As in the case of channel catfish, I suspect that disturbance of a flathead in the early stages of guarding the nest results in destruction of the nest either by the guardian fish or by predation resulting from its absence.

The hole occupied by the above fish was one that I had dug seven to nine inches in diameter and extending two and one-half to three feet into the bank. At the time this fish occupied the hole its depth was approximately the same as originally, but the entrance had been enlarged to 14 inches in diameter, and the chamber widened to 32 inches. The holes were checked later in the summer and all were heavily silted or had been undercut by action of the current.

The number of flathead of catchable size was not reduced as severely during my study as was the number of large channel catfish. Flathead have a longer life-span than channel catfish; therefore, it is not surprising that, of flathead and channel catfish that survived the drought, a higher proportion of flathead persisted throughout the next three years, in which my study was made. In drought, when fish were concentrated in residual pools, the piscivorous (fish eating) habit of flatheads may have favored their survival.

The growth rate of flathead taken from the Neosho River in 1957 and 1958 was reported by Minckley and Deacon (1959:351-352). Individuals hatched in 1955 and 1956 and collected in 1957 had attained average sizes of 9.5 inches and 4.8 inches, respectively, by the end of the 1956 growing-season.

Flatheads of the 1956 and 1957 year-cla.s.ses attained average sizes of 8.7 and 3.2 inches, respectively, by the end of the 1957 growing season.

These data indicate that growth was r.e.t.a.r.ded in the summer of 1957. Many species, including _P. olivaris_, had an exceptionally large hatch in 1957, a.s.sociated with increased water levels in that year. Despite the great increase in amount of water, I suppose that young-of-the-year and yearlings were subjected to crowding resulting from exceptional hatches.

This caused reduction in growth of young flathead, and probably in several other species.

Food of flatheads 4.0 inches and shorter was nearly all insect larvae; that of fish 4.1 to 10 inches was insect larvae, fishes and crayfish; and that of larger flatheads was mostly fish and crayfish. The specific kind of food eaten was correlated with abundance of the food item in the stream (Minckley and Deacon, 1959:350-351).

#Noturus flavus# Rafinesque

Stonecat

The stonecat was not taken at the upper Marais des Cygnes station, and was less abundant at the middle Marais des Cygnes station than at other stations. The abundance of the stonecat was greatest at the lower Marais des Cygnes station in 1957 and at the upper Neosho station in 1959. The species increased in abundance from 1957 to 1959 in the Neosho River, where the princ.i.p.al habitat was riffles over rubble bottom.

Thirty-three stonecats were marked at the upper Neosho station in 1959.

Five of these were recaptured three hours after release, all near the point of release. One individual was taken from a riffle, fin-clipped, and released at the foot of the next riffle downstream. When recaptured four days later, this fish was still in the area of release.

Young-of-the-year were taken on July 1, 1959, at the lower Neosho station.

#Noturus gyrinus# (Mitchill)

Tadpole Madtom

Trautman (1957:444-445) describes the habitat of the tadpole madtom as "low-gradient lowland streams, springs, marshes, oxbows, pothole lakes, and protected harbors and bays of Lake Erie, where conditions were relatively stable, the water was usually clear, the bottom was of soft muck which generally contained varying amounts of twigs, logs, and leaves, and where there usually was an abundance of such rooted aquatics as pondweeds and hornwort. The species seemed to be highly intolerant to much turbidity and rapid silting,..." The tadpole madtom was obtained only at the middle Marais des Cygnes station in a small, deep, mud-bottomed pool in 1957 after water levels, and probably turbidity, had been low for five years. The occurrence provides the westernmost record station in Kansas. Cross and Minckley (1958:106) reported the species from the lower part of the Marais des Cygnes in Kansas.

#Noturus nocturnus# Jordan and Gilbert

Freckled Madtom

The freckled madtom was taken only at the middle Neosho station on 19 April, 1958. This species occurs most frequently in small streams, and individuals living in the mainstream of the Neosho probably are "strays" from nearby tributaries. This species may have utilized the mainstream as a refugium in the drought of 1952-'56.

#Noturus exilis# Nelson

Slender Madtom

The slender madtom was taken only at the middle Marais des Cygnes station in the fall of 1957. This species prefers permanent riffles of clear streams (Deacon and Metcalf, 1961:317). My specimen possibly strayed from a nearby tributary; or, it was a relict from a population living in the mainstream during drought.