LAND FOR WILD LIFE AND RECREATION 213 



they are such popular table delicacies their numbers have been 

 rapidly decreasing. 15 However, the salt water fish depositing 

 their eggs in fresh water have been most severely depleted. They 

 reached their peak production before 1897 and have been declin' 

 ing ever since. 16 As a result of this overfishing, we must now 

 depend for food on fish that formerly were considered useless. 



In addition to overfishing, man has endangered this valuable 

 food resource in another way. Shrimp, oysters, and lobsters, 

 which live in the shallow waters near the shore, are affected by 

 the streams which flow into the sea. These streams have become 

 polluted with industrial waste and sewage. This waste destroys 

 the food supply and poisons the fish. 



Human interference with rivers has another influence on 

 fish which live near the shore or depend on fresh water for 

 spawning grounds. Even though the water which flows in the 

 stream may be pure, if the volume of the stream is greatly 

 reduced by water being drawn off for irrigation, the fish may 

 be unable to reach the spawning ground. In addition to this, 

 when little fresh water flows from the mouth of a stream, the 

 percentage of salt water at the mouth becomes so strong that the 

 enemies of shrimp and oysters can come into this border sone 

 and destroy them. 



There is another problem raised by man's use of rivers. Some 

 salt water fish, particularly the salmon, spawn in fresh water. 

 In many cases the dams built for power and irrigation block their 

 route to the spawning grounds. On the Columbia River, the 

 building of Bonneville Dam has raised a more serious problem. 

 The salmon is the most valuable fish caught in American waters. 

 It has been greatly overfished; but even today, when the salmon 

 are running up the rocky gorges of the upper branches of the 

 Columbia River, you could stand on the bank like the Indians, 

 and spear fish all day. But what will happen when the new 



15 Van Hise and Havemeyer, op. cit., p. 476. 



16 Loc. cit. 



