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BULLETIN OF THE BUREAU OF FISHERIES 
to unfavorable conditions for breeding rather than to lack of food supply. The fact 
that carp seemed to have suffered less than buffalo fishes agrees well with the fact 
that carp are known to be more adaptable than the other fishes. It may be added 
that in 1926 the reports of diminution of carp were also heard at Muscatine and 
Fairport. The carp taken immediately below the dam and as far as Warsaw are said 
to be very poor; the carp found near Canton are variable — some very good and some 
very “slim.” 
SUMMARY AND CONCLUSION 
The carp, or so-called “German carp,” ranks with buffalo fishes and catfishes 
as the most important food fishes of the Mississippi Basin as a whole and of the region 
of Keokuk, both in the lake and in the river below the dam. Although manifesting 
a tendency to move from place to place, and probably working upstream when in 
search of spawning grounds, its prosperity is evidently independent of extensive 
migrations, and there is no reason to suppose that the fishery can be unfavorably 
affected by the Keokuk development. 
Up to 1917, at least, a marked increase in the abundance of carp in the lake was 
evident, but the statistics of 1922 (as well as those of 1927) indicate that the increased 
abundance was not maintained, although in 1922, and just before and after, there 
were notable runs of carp in the northern portion of the river. The marked decline 
in abundance of carp has apparently been due to changes in conditions affecting the 
breeding of carp and buffalo fishes. The carp and the buffalo fishes taken in the lake 
are said to be exceptionally fat and well flavored, so that in the large markets they 
command prices higher than are paid for the same species of fish from any other parts 
of the river. Fishermen generally complain of a relative scarcity of young carp in 
the region. A recent general decline in abundance of carp in the river is indicated. 
Remarkable catches of carp in the region of Lake Pepin were made in 1922 and 
about that year, but we are not able to relate this to the presence of the dam. 
There is described a most striking aggregation of carp at the dam, occurring 
just after the middle of July, 1916, and an obvious explanation for the condition 
is furnished in the mass emergence of May flies self-propagated in the lake above. 
Minnows. Notropis atherinoides Rafinesque; 24 Notropis jejunus Forbes 
SHINERS 
About 15 species of minnows were taken in the vicinity of Keokuk in the course 
of the investigation, but only the two species named above were found to be present 
in sufficient numbers to be of evident significance in the economy of fish and man. 
These appeared to constitute the chief food of fish-eating fishes inhabiting the river 
at this point and are the principal bait fishes used by anglers. In 43 hauls of the 
minnow seine made from May 3 to September 2, 1916, including some from each side 
of the river and all being within 2 miles below the dam, there were taken 299 jejunus, 
455 atherinoides, and 4 specimens of other cyprinids. Both species were found in 
February and in each month from April to September, inclusive. No effort was 
made to secure them in the other months. Jejunus comprised about one-third of the 
minnows taken in the river at Keokuk, and it was also found in the lake near Montrose 
» Following Forbes and Richardson (1908), N. arge and N. dilectus are treated as synonyms of N. atherinoides. N. rubifrons 
(Cope) was looked for but not found. Changes of nomenclature suggested by Hubbs (1926) were not available at the time of our 
field observations, and the modification of our nomenclature at this time would be at the risk of confusion rather than clarification 
in our records. 
