610 EEPORT OF THE COMMISSIONER OF FISHERIES. 



make excelle::t 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 lar^e 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 



« 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 as I am aware nothing has been done as yet with a fish. Tliat 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. 



