184 BULLETIN OF THE BUREAU OF FISHERIES 
the production of suckers from commercial fisheries of the Mississippi River and 
tributaries for various years. 
Pounds 
1894 2 , 178 , 608 
1899 2 , 243 , 934 
1903 1 , 109 , 276 
1908 892 , 000 
1922 699 , 539 
Since the general decline was more marked between 1899 and 1903 and again 
between 1903 and 1908 than in the longer period between 1908 and 1922, the dam 
built in 1913 can not be held primarily accountable for the general depreciation of the 
sucker fishery. As regards Lake Pepin, the yield was little less in 1917 than in 1914 
but much greater in 1922. (See Table 7, Coker, 1929.) In Lake Keokuk, however, 
the small sucker fishery of 1914 (4,640 pounds) had almost disappeared in 1917 (700 
pounds) and was not found at all in 1922. This local decline is very likely due to the 
changed conditions in the area covered by the lake, but its significance does not seem 
great. 
At first thought it would seem clear that the dam has been responsible for the 
loss of the blue sucker from the upper river, either directly, by preventing the upward 
passage of fish from the lower river, or indirectly, by destroying favored schooling and 
breeding grounds in the rapids. Against this conclusion it may be argued that the 
blue sucker has largely disappeared from the lower river as well. This is a question 
of fact that should be determined more definitely. The limited information that we 
have regarding the river far below Keokuk points to that conclusion. We know that 
the fish is no longer common in the river from Keokuk to Canton, well below the dam. 
It is decidedly important that its occurrence in the Mississippi and its tributaries far 
below Keokuk should be investigated carefully. 
River quillback. Carpiodes carpio (Rafinesque) 
CARP sucker; silver carp 
While other carp suckers or quillbacks are occasionally found at Keokuk, the 
“river quillback” ( carpio ) is the only species constituting a notable fishery product. 
Forbes and Richardson (1908) report that the blunt-nosed carp sucker ( difformis ), 
common throughout Illinois, prefers the shallow waters of small streams; another 
species ( velijer ) is most abundant in northern Illinois; and the fourth species ( thomp - 
soni) is characteristic of the Great Lakes region. 18 
The river quillback is small and of minor value as a food fish. Forbes and 
Richardson (1908) say, regarding this species ( C . carpio)-. “It is said by Mississippi 
River fishermen sometimes to reach a weight of 10 pounds. It is sold for food, but is 
flavorless and soft.” In summer it is shipped irregularly from Keokuk, being said to 
keep badly in warm weather; in winter it constitutes a low-priced fishery product. 
Some fishermen say that other fish will not eat the river quillback, and it is a fact that 
they have not been found in stomachs of other fish during the present investigation. 
Forbes (1888a, p. 480) found them in the food of other fishes, but to what extent does 
not appear. The explanation of their not being found as food fishes at Keokuk may 
lie in the fact that the stomachs examined were from fish collected in the river, where 
young quillback are rarely found. In the fall of 1916 some were found along the 
i» Call (1892) says of C. velifer: “This is, beyond doubt, the most abundant of the buffalo fishes [siel] in Iowa.” He also says 
that it is found in rather deep but muddy waters, which is not in agreement with the observations of some others. 
