282 



THE VERTEBRATE ANIMALS 



This instinct of this fish and other species to go into shallow rivers 

 to deposit their eggs has been made use of by man. At the time 

 of the spawning migration the salmon are taken in vast numbers. 

 The salmon fisheries net over $16,000,000 annually, the shad at 





least $1,500,000, the smelt fishery nearly $150,000 more. The 

 total annual value of the fisheries of the United States is over 

 $50,000,000. 



Migration of Fishes. Some fishes change their habitat at dif- 

 ferent times during the year, moving in vast schools northward 

 in summer and southward in the winter. In a general way such 

 migrations follow the coast lines. Examples of such migratory 

 fish are the cod, menhaden, herring, and bluefish. The migra- 

 tions are due to temperature changes, to the seeking after food, 



Fisheries Percentage Product 



, IP 20 3,0 40 50 60 70 8,0 9,0 



W//M/////////A W///A 1 



United States Gt.Brit. & Ir. 



Can. & 



Newf. 



Japan Russia France 



Rest of World 



and to the spawning instinct. Some fish migrate to shallower 

 water in the summer and to deeper water in the winter ; here the 

 reason for the migration is doubtless the change in temperature. 



The herring fisheries have always been a source of wealth to 

 the inhabitants of northern Europe. The banks and shallows of 

 the coast of Newfoundland were undoubtedly known to the Norse- 

 men long before the discovery of this c^ untry by Columbus. 



