132 
BULLETIN OF THE BUREAU OF FISHERIES 
time — buffalo and carp. (6) Five kinds show, first, moderate decline, then increase — 
drumfish, quillback, paddlefish, lake sturgeon, and suckers — and all but the quill- 
back were taken more abundantly in 1922 than in 1914. (c) Three kinds of fishes 
show, first, material increase, then decline — bowfin, catfish, and mooneye — but the 
catches of bowfin and catfish were still much greater in 1922 than in 1914, while the 
mooneye was not represented at all in 1922. 
3. Lake Keokuk offers a different story: (a) Two kinds of fish, at least, show 
a progressive increase in yield from 1914, through 1917, to 1922 — catfish and paddle- 
fish. This is true, also, of the leading gamefish — black bass, crappie, and sunfish — 
if the figures are to be accepted as correct. ( b ) Three kinds gave greatly increased 
yields in 1917 but reduced yields in 1922 — -buffalo, carp, and drum — the yield of 
drumfish being reduced only as compared with 1917, since it was still as great as in 
1914. (c) Three kinds show steady decline, the catches being small even in the 
first year and not appearing in the last year — eels, sand sturgeon, and suckers. ( d ) 
Two fishes figured only in the products of 1917 — bowfin and quillback. 
From the statistics of the commercial fisheries we can derive no impression of 
diminution of fishes in Lake Pepin following the construction of the dam. The 
quillback and possibly the mooneye offer the only possible exceptions. It must be 
said, however, that at least two species of buffalo fish play a part in the fishery but 
are not distinguished by statisticians, and, therefore, there remains the possibility 
that one has diminished while the other has increased, although there is no evidence 
to that effect. A similar statement may be made in regard to catfish. 
As regards Lake Keokuk, the only kinds of fish of commercial importance in 
1914 that were taken in less abundance in 1922 were buffalo fish and carp, fishes 
that showed increasing yield in Lake Pepin. Eels, sturgeon, and suckers also declined 
or disappeared; while commercially unimportant in the locality, these fishes are to 
be regarded as potentially important. However, since lake sturgeon and suckers 
maintained their place in Lake Pepin, it is evident that they were not excluded from 
the upper river. The sturgeon of Lake Keokuk (the shovelnose) presents another 
question. 
The statistics for 1927 offer a picture distinct from those of the preceding years 
of report but do not seem to necessitate substantial modification of the statements 
made in the two preceding paragraphs. We have to do possibly with one of those 
occasional years of very poor conditions for the fishery. 
The relatively very large catches of buffalo fish, carp, and drum from Lake Keokuk 
in 1917 offer a nice problem. Possibly we have here another illustration of an appar- 
ently common rule of development of newly formed lakes. According to this rule, 
if it may be so called, there occurs, first, an increase of the smaller animals and 
plants that constitute the food supply of larger fish; second, a great multiplication 
and growth of the larger feeders (fish) until the crest of a wave of fish population is 
attained; third, a depletion of food supply as a result of overabundance of feeders; 
fourth, depletion in numbers or diminution in average size of fish until the fish popu- 
lation is at the trough of the wave; and finally, an approximate biological balance 
when fish are less abundant than they were at the crest of the wave and perhaps 
more abundant than at the trough of the wave. If this explanation applies, later 
surveys may show improvement. If the reclamation of submerged lands is the 
cause of the fall of the catches, no material improvement is to be expected. It is 
