192 The Life Story of the Fish 



in the stream where they belonged, they are so few in pro- 

 portion as to be negligible. Fish do stray, as no one doubts 

 — even humans make mistakes — ^but the general truth of the 

 principle is not to be questioned. 



Most of us can look upon this phenomenon with a satis- 

 fying degree of wonder and humility. However, scientists 

 are by nature and training skeptics. They must, if they are to 

 be good scientists, never accept things at face value. They 

 must look for flaws and possible loop-holes. They must de- 

 termine whether what seems to be cause and efFect is not 

 really due to chance. And some of them pointed out that 

 chance might play a large part in the return of the salmon. 



According to this hypothesis, salmon go out from the 

 estuaries into the sea, follow along the submarine river-beds 

 until they get to the point where the bottom slopes off 

 steeply at the edge of the continental shelf, and there re- 

 main to feed and grow until the time for spawning. They 

 then seek the nearest fresh water, and this is the river out 

 of which they came, whose "influence" they have never left. 



Most of the men closely involved in the salmon studies 

 had to admit the possibility of this hypothesis, but felt that 

 it did not jibe with things which they knew almost certainly 

 to be true, but could not prove to be scientific facts. In the 

 meantime another government program was piling up evi- 

 dence in their support. This time it was not a matter of cut- 

 ting off fins, but of numbering the fish. Men went to sea in 

 ships, caught salmon in nets all up and down the coast, and 

 fastened to each fish a small plate with a serial number on 

 it. When these numbered fish were recovered on their spawn- 

 ing-runs, it was possible, by looking in the records, to find 

 the exact spot in the sea where each had been marked. It 

 was found that some fish had wandered as far as fifteen 

 hundred miles from the mouth of their "home" estuary. 

 It was found that most of the chinook taken by the fisher- 



