FISHES 151 



changes usually are accomplished for the purpose 

 of making provision for a new diet, for it has already 

 been shown that the food of young fishes is often 

 different from that of the adults. 



Effects of Fishing 



Over-fishing, fishing during breeding seasons, tak- 

 ing and destroying young fish, have been carried on 

 to such an extent that previously important fishes 

 have ceased to be of commercial value. This appears 

 to have taken place in some localities with respect to 

 the salt-water sheepshead. The bluefish and the hali- 

 but appear to be destined to suffer the same fate. 

 The possibility of exterminating a species through 

 fishing, however, seems very remote. The destruction 

 of spawning grounds, or making them inaccessible 

 by dams and other obstructions, or by destroying 

 their usefulness through pollutions, may in the end 

 exterminate species spawning in the rivers and near 

 shore. 



The status of our fisheries is such that conserva- 

 tion deserves renewed, intelligent, and earnest atten- 

 tion. Our knowledge of the habits and life history 

 of many species is still inadequate. The effects of 

 agricultural drainage, of the disappearance of our 

 forests, and of industrial development upon our fish- 

 eries has not been adequately studied. Sane and 

 sound means of conservation have not been fully 

 developed, and much work remains to be done. 



Present-day measures of conservation consist 

 mainly in restricted fishing; that is, in providing a 

 closed season when no fish may be caught, or in mak- 



