610 REPORT OF THE COMMISSIONER OF FISHERIES. 
make excellent bait for bass, and perhaps other fish, but I do not know 
that they have been tried. 
On account of its hardiness and the readiness with which it will 
accommodate itself to small quarters the carp makes an excellent aqua- 
rium fish for exhibition purposes. At the large market in Boston there 
are several large carp in a glass tank so small that the fish now have 
barely room to turn around. It is said that these same fish have been 
there for a number of years. 
When carp began to be common in Lake Erie it was suggested by 
many that perhaps the air bladders, or ‘‘ sounds,” as they are called, 
might be used for the manufacture of isinglass, which is extensively 
used in clarifying wines and in similar ways. At present about the 
only fresh-water fish whose sound is used for this purpose is the stur- 
geon, and the sturgeon fishery is comparatively so small that the sale 
of the sounds amounts to very little commercially. Those who had 
tried to use carp sounds for this purpose had not been successful. 
Nevertheless, at my suggestion, Mr. John Tufts, of the Cape Ann 
Isinglass Company, made further tests on some sounds which were 
procured for me by Mr. Cleaver, of the firm of R. Bell & Co., Port 
Clinton, Ohio. Mr. Tufts writes me as follows: 
In regard to the carp sounds which you sent me, will say that I have tested them 
and find that [they] will not answer our purpose, inasmuch as they do not seem 
to contain any glue. 
Finally, where carp are taken in greater numbers than can be used 
for food, or where the attempt is being made to rid waters of them, 
they can always be used for the manufacture of valuable fertilizer. 
The importance of fish for this purpose and the extent of the industry 
in some parts of the country, have recently been well described by 
Stevenson (1903). Fish refuse is regularly sent from many fish houses 
in the region to the fertilizer factory at Sandusky, but under present 
conditions carp contribute very little to this, being shipped almost 
entirely in the round. 
The possible value of the carp as a game fish will be discussed in a 
later section (p. 619).¢ 
THE CARP FISHERIES. 
Within the past decade the carp fishery has increased to such an 
extent in the general regions of Lake Erie and the Illinois River that 
it now forms a recognized and independent industry. Although it 
a There is one purpose for which the carp would afford valuable opportunity which has not been 
mentioned—that is, as material for scientific study of variation and heredity among fishes. Experi- 
ments in this line have been actively prosecuted in recent years, especially with plants and mam- 
mals; but so far asI am aware nothing has been done as yet with a fish. That the carp would be an 
excellent subject for such experiments is evident from its great variability, its adaptation to domesti- 
cation and the consequent ease with which it can be reared, its hardiness and rapid growth; and, 
finally, its great fertility, affording abundant material for quantitative results. Probably the only 
rival of the carp as a fish for this purpose would be the gold-fish, which might be preferable on 
account of its smaller size. 
