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BULLETIN OF THE BUREAU OF FISHERIES 
region. 2 About 60 species of fish were found in the Mississippi within 10 miles 
below the dam, while about 10 others were collected in near-by waters. About 30 
species are common enough to be of direct or indirect economic importance; the 
discussion that follows is restricted principally to species of which 50 or more examples 
were observed. Each species is considered, as far as practicable, with reference to its 
economic importance, its breeding habit and range, its known or supposed migrations, 
its seasonal occurrence, and its abundance at Keokuk and in Lake Pepin (400 miles 
above) both before and after the construction of the dam. We have not hesitated to 
cull data from all available sources regarding the natural history of the significant 
species, not only because such information formed the necessary background for our 
own study but also in order that the reader might be able to make his own inferences 
regarding the probabilities or possibilities of the effects upon the several species both 
of the dam as an obstruction and of the pool above, the dam as a body of water pre- 
senting a new set of conditions for feeding, growth, and breeding. 
One thing in the account that we think of value is the directing of attention to the 
surprising gaps in our knowledge of the most elemental facts of the life histories of 
common fishes. To say nothing of the paddlefish and hackleback sturgeon, who 
knows when, where, and under what conditions occurs the breeding of fresh-water 
drum, blue sucker, river herring, or Ohio shad? The last-mentioned fish, potentially 
an excellent food fish and fairly abundant, as our observations indicate, has not even 
been recorded hitherto from the Mississippi River. Who has observed the breeding 
(in nature) of any of the larger catfishes of the Mississippi Basin? Where is the 
“niggerlip ” catfish during the 10 months of the year, when it is rarely taken by com- 
mercial fishermen? Who has studied the modifications of form and color correspond- 
ing to habits or ages of any of the catfishes or buffalo fishes? There are excellent 
opportunities for useful studies of fishes that can be readily found in various streams 
of the Mississippi Basin. 
Paddlefish or spoonbill cat. Polyodon spathula (Walbaum) 
The paddlefish is valued for its flesh, used both fresh and smoked, and especially 
for its roe, which is made into caviar. It is of peculiar general interest as a species 
that is almost unique, being markedly different in form and structure from any other 
fish now living except a single species occurring in certain rivers of China. Sharklike 
in form, but not in behavior or in quality of meat, it ranks as one of the most estima- 
ble aquatic resources. At times it has seemed upon the verge of extermination from 
overfishing or other unfavorable conditions, yet apparently it shows remarkable 
powers of endurance or recuperation. Since the roe of an individual fish may weigh 
10 to 15 pounds and is sometimes worth more than $2 a pound, a large paddlefish 
may represent a very valuable catch. Until recently, at least, the flesh of the fish 
was not generally sold under its own name but might appear in the markets fresh or 
smoked under the name of “sturgeon.” In Lake Pepin, in fact, a common name 
used by the fishermen and applied to the living fish some time ago was “shovelnose 
sturgeon.” 
The paddlefish is found only in rivers and lakes of the Mississippi Basin and in 
some other tributaries of the Gulf of Mexico. While it is rare in shallow tributaries 
2 As related in connection with the companion report (Coker, 1929), the studies upon which the two papers are based were made 
during many years. For some time Emerson Stringham, then scientific assistant in the Bureau of Fisheries, collaborated in these 
studies. He spent the greater part of two years at Keokuk making experiments and observations that have contributed materially 
to both reports. The acknowledgments made in the other report apply as well to the present paper. 
