276 



ZOOLOGY 



time of the spawning migration the salmon are taken in vast 

 numbers. The salmon fisheries net over $13,000,000 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. But the profits from these fisheries are steadily 

 decreasing because of the yearly destruction of untold millions of 

 eggs which might develop into adult fish. State and government 

 interposition is in many cases coming too late, for at the present 

 rate of destruction many of our most desirable food fishes will 



Fisheries — Percentage Product 



JiL 



20 



JL 



^ 



IL 



J°.- 



ii° 



8.0 



m 



JL 



United States Gt.Brit. & Ir. 



Can. & 

 Newf. 



Japan 



Russia France ^'•^•, 



Rest of World 



soon be extinct. The sturgeon, the eggs of which are used in the 

 manufacture of the delicacy known as caviare, is an example of a 

 fish that is almost extinct in this part of the world. 



Other deep-water fish do not go up rivers to spawn, but lay their 

 eggs in the sea. In such eggs there is found a tiny oil drop, which, 

 being lighter than water, causes the egg to come to the surface of 

 the water, where the heat of the sun may favorably influence 

 development. Other fish change their habitat at different 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, 



