the proper main stream but also 

 leads him upstream to the exact 

 tributary from which he emerged as 

 a small fish. In reaching this 

 stream, he probably will have 

 passed and ignored many other 

 streams flowing from watersheds 

 similar to the one for which he is 

 bound. Many such streams are 

 identical so far as man can deter- 

 mine, but the salmon senses a differ- 

 ence. Hoar (1951) and Black 

 (1951) are of the opinion that the 

 thyroid hormone indirectly influ- 

 ences the migration of fish. 



It is believed that the entrance of 

 salmon into their natal stream to 

 begin the upstream journey to their 

 species' spawning areas is deter- 

 mined neither by chance nor by de- 

 gree of maturation of sexual prod- 

 ucts. Lloyd Eoyal (1951) of the 

 International Pacific Salmon Fish- 

 eries Commission presented inter- 

 esting facts and theories on this 

 f)oint. Years of investigation of the 

 Fraser River (Canada) stocks of 

 red (sockeye) salmon have revealed 

 that there are distinct races entering 

 the river and bound for spawning 

 areas at greatly varying distances 

 from the ocean. After "loitering" 

 in the general area at the mouth of 

 the Fraser for a time, each race will 

 quite suddenly move upstream to- 

 ward its tributary-stream spawning 

 area. It appears that the red 

 salmon of the various races time 

 their departure so as to arrive at the 

 spawning area, "whether 30 or 730 

 miles from the sea," at the period of 

 appro})riate water temperatures at 

 that point. Too-early arrival re- 

 sults in ineffectual spawning during 

 high water temperatures. Late ar- 



rival results in nonproductive 

 spawning because of low tempera- 

 tures. Studies in other places have 

 not been so intensive as those on the 

 Fraser, and consequently neither 

 corroborative nor contradictory evi- 

 dence is available; but the Fraser 

 River study suggests the effect that 

 manmade obstructions have on the 

 races by delaying individuals on 

 their upstream migration. 



Economic Value 



The most recent complete records 

 compiled by the United States Fish 

 and Wildlife Service and by the De- 

 partment of Fisheries of Canada 

 reveal the magnitude and impor- 

 tance of the commercial salmon fish- 

 ery to the economy of the Pacific 

 coast. 



In 1951 the commercial fishermen 

 operating in Alaskan waters landed 

 277 million pounds of salmon, for 

 which they received 32.4 million dol- 

 lars. Pink, red, and chum salmon 

 made up the bulk of the catch. The 

 salmon prepared for market, includ- 

 ing 165 million jDounds of canned 

 salmon valued at 79 million dollars, 

 totaled 189 million pounds valued at 

 86 million dollars. 



The catch in the waters of Ore- 

 gon, Washington, and California 

 for 1951 totaled 98 million pounds 

 valued at 20 million dollars to the 

 commercial fishermen and at about 

 three times that value for the final 

 market product. Chinook, silver, 

 and chum made up the bulk of the 

 catch. The landings in Washing- 

 ton, Oregon, and California were 77, 

 14, and 7 millions of pounds, respec- 

 tively. 



14 



