n8 



ECONOMIC ZOOLOGY 



food and their eggs, which are small and produced in enormous num- 

 bers (one female, it is estimated, may produce 3,000,000 in one season) 

 are made, especially in Russia, into Caviare. Besides this, from their 

 air-bladder is made isinglass, as was noted above. 



Besides these few, hundreds of species of useful fishes might be 

 mentioned, as there are probably but few that are not used as food by 

 somebody, somewhere. 



' 



FIG. 84. Sword-fish (Tetraptu'rus), yellow-fin tuna, and yellow tail, caught 

 with rod and reel at Santa Catalina Island. (From Dougherty, Economic Zoology, 

 after Bulletin of B. of F., vol. xxviii, 1908.) 



Fish-culture. The possibilities of fish-culture have been long recog- 

 nized. This science was practised in early ages by the Chinese and later 

 by the Romans. It was introduced into the United States about 1865; 

 and in 1871 the federal government established the United States Fish 

 Commission, now known as the Bureau of Fisheries. While the chief 

 work of this Bureau is, perhaps, the artificial propagation of food 



