190 The 1a] e Story of the Fish 



inquisitive Izaak Walton tied ribbons on the tails of fish in 

 the hope of finding out where they went. It seems likely 

 that small boys, or poachers, or fishermen, feeling sure that 

 they recognized the same old salmon back in the same old 

 pool, first got an inkling of what was happening. It seems 

 likely that scientists at first laughed at them, and classed the 

 suggestion with folklore and old wives' tales. Like many 

 another old wives' tale, it has proved to be truth. Science 

 has come to have more respect for old wives' tales than it 

 once did. 



When scientists took up the serious study of the salmon 

 on account of its fisheries' value, they themselves began to 

 find evidence in favor of the theory. They found that the 

 fish in certain streams year after year showed strong racial 

 characteristics — such as size, or fat-content, or coloratipn, or 

 age at going to sea, or length of time spent at sea, or age at 

 maturity. They found that with experience they could come 

 pretty close to telling what river a fish was taken from just 

 by examining its scales. They felt that these traits were 

 probably hereditary. If fish from other parts, with different 

 traits, came into the stream, how could these differences 

 continue to exist? Only if the fish born in each stream re- 

 turned to that stream to spawn could the racial differences 

 be maintained. 



They found that if the run of fish in a given stream were 

 destroyed or prevented for several successive years, so that 

 salmon ceased to be born and to grow up in that stream, the 

 salmon did not return to it, even though conditions might be 

 highly favorable for spawning. They found that in many 

 rivers the pink salmon have a very heavy run every other 

 year, a very light run in the intervening years. As we have 

 seen, pink salmon all mature at two years. If fish came in 

 from other streams, there would be no reason for this alter- 

 nation j but if they did not, there would. For it is obvious 



