194 
BULLETIN OF THE BUREAU OF FISHERIES 
turbidity of the lake water generally and consequently in sedimentation. In any event 
the results of future statistical surveys may be awaited with special interest. 
SUMMARY AND CONCLUSIONS 
The buffalo fishes, including two or three species of the most valuable food fishes 
of the basin, breed far north and far south of Keokuk, and their migratory movements 
are presumably very limited as to length of journey along the course of the river. We 
find no evidence that the dam has any effect on the abundance of buffalo fishes in 
distant parts of the river, as in Lake Pepin, nor any marked effect on the abundance 
of them in the river just below the dam. The conditions as concerns these fishes in 
the lake above the dam seemed baffling at first. A very marked and encouraging 
upward trend of the fishery, as revealed by statistical data for 1917, was followed 
by a very discouraging decline shown in 1922. Between these dates the most exten- 
sive areas evidently suitable for spawning and nursery purposes had been reclaimed 
from the water for purposes of land farming, and changes had also occurred over the 
submerged islands away from the mainland shores, which would seemingly prevent 
their serving as substitute spawning grounds. The sequence of events gives the strong- 
est reasons for assuming that the very recent decline of the commercial fishery for 
buffalo fishes and carp in the lake is attributable to the loss of breeding grounds. 
That it is lack of effective reproduction rather than of food that accounts for the de- 
cline in numbers of buffalo fish taken is further attested by the fact that the fatness 
of the fish from the lake gives them a notably higher value in the biggest markets. 
Evidently there is food enough for the fish, if not fish enough for the captors. 
THE CARP AND MINNOWS (Cyprinidae) 
The minnow family is not always thought of as representing one of the chief 
economic assets of our waters. Yet the family is most important for two reasons: 
first, because it includes the carp, esteemed by some, hated by others, but always 
held significant; and, second, because it includes the real minnows — those “young 
fishes which never grow up.” “It is not too much to say,” we quote Forbes and 
Richardson (1908), “that the number of game fishes which any water can maintain 
is largely conditioned upon its permanent stock of minnows.” 
It might be supposed that, since there is such a large number of species of minnows 
of such varied adaptation to all sorts of ecological conditions, there could be no 
minnow problem in connection with a water-power development. Such a supposi- 
tion would be ill founded. The author has made observations on a series of lakes 
resulting from a water-power development in western North Carolina, where the 
waters were almost entirely open, the shores and bottoms having been effectively 
cleared of trees and brush in almost all parts, and where, unfortunately, the conditions 
were unfavorable for the growth of submerged vegetation. The small streams 
tributary to the lakes contained minnows, but in the open waters, stocked with 
game fishes, there was virtually no chance for a minnow to survive and repro- 
duce. It was reliably reported that in the first years of the lakes there had been great 
swarms of minnows hugging the shores and strenuously preyed upon by the game 
fish, which developed in numbers most gratifying to the angler. At the time of these 
observations practically no minnows could be found; many seine hauls in the lakes 
brought only the young of game fish. (Coker, 1926.) The sport-fishing in the lakes 
had shown a lamentable decline, doubtless because the game fish could prey only 
upon each other. 
