River carpsucker were abundant throughout the study at all stations.
Adults were taken most frequently in quiet water, but depth and
bottom-type varied. The greatest concentrations occurred in mouths of
creeks during times of high water; occasionally, large numbers were
taken in a shallow backwater near the head of a riffle at the middle
Neosho station. River carpsucker feed on the bottom but seem partly
pelagic in habit. They were taken readily by means of the shocker and
gill nets at all depths. The population of _C. carpio_ in the Neosho
River probably was depleted by drought, although many individuals
survived in the larger pools.
When stream-flow was restored, carpsucker probably moved rapidly
upstream but had a scattered distribution in 1957. Trautman (1957:239)
states that in the Scioto River, Ohio, river carpsucker moved upstream
in May and downstream in late August and early September. Numbers found
at the middle and lower Neosho stations suggest similar movements in the
Neosho River in 1957. In midsummer they were common at the middle
station but rare at the lower station; however, they became abundant at
the lower station in November. The abundance in late fall at the lower
Neosho station might have resulted either from downstream migration or
from continued upstream movement into thinly populated areas. No
indication of seasonal movement was found in 1958 or 1959.
River carpsucker reach maturity at approximately 11 inches T. L., and
spawning occurs in May or June. A ripe male was taken from a
gravel-bottomed riffle, three feet deep, at the middle station on the
Neosho station on 10 June 1959.
The size-distribution of individuals taken at the middle Neosho station
is presented in Fig. 2. The collection in early July of 1958 indicates
that one size-group (probably the 1957 year-class) had a median length
of approximately seven inches. The modal length of this group was nine
inches in June, 1959. A second, predominant size-group (Fig. 2) seemed
to maintain almost the same median size throughout all the collection
periods, although specimens taken in the spring of 1959 were slightly
smaller than those obtained in 1958. This apparent stability in size may
have been due to an influx of the faster-growing individuals from a
smaller size-group, coupled with mortality of most individuals more than
14 inches in length.
Young-of-the-year were taken at every station. Extensive seining along a
gravel bar at the lower Neosho station indicated that the young are
highly selective for quiet, shallow water with mud bottom. In these
areas, young-of-the-year carpsucker were often the most abundant fish.
River carpsucker were collected more readily by use of the shocker after
dark than in daylight (Table 9, p. 402).
[Illustration: FIG. 2. Length-frequency of river carpsucker
in the Neosho River, 1958 and 1959.]
#Carpiodes velifer# (Rafinesque)