BY-PRODUCTS OF FISHERY INDUSTRIES 213 



years, and shark-skins have come to be of consider- 

 able value. Thus the demons of the sea which are so 

 destructive of fishermen's nets have been found to be 

 a blessing in disguise. Until their skins became of 

 value it was thought that sharks were exceedingly 

 numerous, but now that a shark fishery has been 

 established, the shark fishermen have found difficulty 

 in catching sufficient sharks to keep up with the 

 demand. 



Despite the very low price at which most fishery 

 by-products are sold, their total annual value to the 

 American manufacturers of these products is about 

 twelve million dollars. About half of this is obtained 

 from fish and whale oils, of which more than thirteen 

 million gallons are produced annually. The quantity 

 of fish scrap produced is also very large, amounting 

 to more than two hundred million pounds. The bulk 

 of this scrap commands a rather low price, as it is 

 sold for fertilizer. 



About half a million gallons of fish glue is pro- 

 duced each year. The manufacturers estimate its 

 value at about six hundred thousand dollars, but the 

 cost to the consumer is several times this amount. An 

 immense quantity of cracked shells is sold as poultry 

 grit, the annual production of about five hundred 

 million pounds bringing more than two million dol- 

 lars. A large amount of oyster shells is also made into 

 lime, which is used for mortar, for plaster, and for 

 agricultural and other purposes. Some clam shells 

 are also crushed and used for the same purposes. 

 Other fishery by-products include shark fins, herring 

 scales, stearin, fish flour, and shrimp bran. 



