Introduotion 



The Salmon River joins xhe Snake River approximate iy 187 miles 

 above the Columbia River confluence. Its drainage area comprises 

 more than 14,000 square miles of central Idaho, and includes a consid- 

 erable portion of the Sawtooth Mountains, as well as the southwestern 

 slope of the Bitterroot Mountains, which also form the bovtndary of the 

 Pacific Slope. The total stream length of the Salmon River system, 

 excluding all minor tributaries, amounts to more than 1200 miles. 



The Salmon River system always has been one of the mainstays in 

 the production of the choice early variety or spring chinook salmon. 

 Some of the lakes in its headwaters also have contributed to the pro- 

 duction of the valuable blueback salmon. In recent years it has as- 

 sumed added importance because of the industrial and agricultural 

 development of other watersheds formerly of major value as salmon 

 spawning areas and the consequent loss of these regions as salmon pro- 

 ducing areas. A considerable part of the system is of value from the 

 standpoint of natural salmon production because it is unmolested by 

 man due to the extremely rugged topography of the watershed, and will 

 probably always remain in its present primitive condition. On the 

 other hand, the present chinook and blueback salmon runs in the easily 

 accessible headwaters area are only a small fraction of their former 

 cize. The value of this river system to anadromous fish will be further 

 reduced if the proposed series of major dams in the Middle Columbia 

 and lower Snake Rivers is constructed. 



The vemguard of the chinook run appears in the upper Salmon River 

 early in June, and spawning occurs in July and August. Inasmuch as the 

 comnercial fishing season in the lower Columbia in past years has not 

 begun until May 1, the majority of these fish have passed through the 

 commercial fishery by that date and have not been subjected to it on 

 their spawning migration. The effect of the marine fishery during the 

 several years of ocean residence is of course unknown for any particu- 

 lar stock of salmon. 



The bluebacks in the Salmon River system spawn in October, consid- 

 erably later than the chinooks. These fish are subjected to an intense 

 commercial fishery in the lower Columbia River, 



A survey of the Salmon River system was undertaken in J\jne and 

 July, 1941. At that time the main Salmon River was very turbid, and 

 for this reason the detailed survey was confined to the larger clear 

 tributaries, except for part of the clear headwaters portion of the 

 main stream above Stanley, Idaho, 



