COMMON FISHES OF MISSISSIPPI RIVER 
197 
there were about 1922, runs of carp on a scale that was probably unprecedented for 
the region. 
As a commercial fish the carp possesses (along with the bowfin) two great advan- 
tages over other commercial fishes. It is easily kept in large numbers in pens or 
other forms of inclosure ; consequently the fish that are caught in summer when the 
market is poor can be held until winter, when they can be shipped more safely and 
sold at a better price. They can be shipped alive at little extra expense; thousands 
of pounds of carp are readily shipped in cars fitted with tanks and equipped with 
a motor-driven pump to force air into the tanks. The motor need be employed 
only when the car is still, for while the train is moving the pump may be driven by 
a connection with the axle of the car. Live carp are, of course, in special demand 
in certain markets. 
In 1915 carp were very numerous in the river in the vicinity of Keokuk; 
the only species that compared with it in abundance were the river quillback, 
short-nosed gar, and one or two minnows. In 1916 carp were still more numerous, 
those taken in the commercial fishery exceeding in weight all other kinds of fish com- 
bined. The breeding season was ascertained by Stringham’s examination of about 
150 examples between the middle of May and the middle of July; the first certainly 
mature male was found on June 2 and the last on July 13. This gives a late season, as 
compared with the observations of others, 22 and it may be that breeding began before 
June; or the breeding season may have been comparatively late because of the si w 
rise of water temperature, which did not pass above 63° F. (17° C.) until May 25. 
Figure 24 represents the seasonal fluctuations in catch for 1916, as determined 
from reports received currently from local markets. The greatest abundance in the 
markets coincided closely with the breeding period, occurring from about the middle 
of June to the middle of July, undoubtedly because the fish, as is well known, move 
out into shallow waters for spawning (Richardson, 1913), giving the fishermen better 
opportunities for capturing them. Carp were seen at Keokuk in each month except 
December, when no observations were made. 
The observations on the carp with reference to the physical structure of the dam 
are significant. Owing to the habit of coming frequently to the top, and because of 
the brilliant yellow or orange color of the fish, it is relatively easy to observe them in 
the water. In the power-house inclosure, described in a previous paper (Coker, 1929) 
carp were seen by Stringham from time to time in 1915 from May 16 to September 24, 
when observations at this point were interrupted. They were also noted near the 
junction of the power house and the dam, and some were captured below open spill- 
ways. Among these were a ripe male taken on June 5 and two others, apparently 
ripe, taken on June 12. The next year, 1916, the species was phenomenally abundant 
in the entire vicinity of Keokuk. From May 30 until the interruption of observations 
after September 15 carp were usually or always to be found in the power-house inclos- 
ure. An enormous quantity was present there from about July 6 to July 15; some 
diminution in numbers occurred from that time onward, but there were still thousands 
in the inclosure by the middle of September. An extraordinary aggregation of carp 
near the lock is described in a following paragraph. Along the bank, between the lock 
and the bridge, many persons were commonly engaged in catching them with hook 
and line. In this short stretch 60 fishermen with hook and line were counted on the 
22 “ Carp spawn in the northern United States in May and June. The eggs are small and exceedingly numerous, 400,000 to 
500,000 being a common number in a 4 or 5 pound female.” (Forbes and Richardson, 1908.) 
