entific regulation of the fisheries 

 would have permitted the escape of 

 the necessary numbers of salmon 

 during the feak of the run, for these 

 were the fish having the greatest 

 successful s p a w n i n g potential. 

 However, biological data were not 

 available to indicate the desirability 

 of such escapement, and extreme 

 decimations of some stocks of 

 salmon resulted. Basically, then, 

 all that is necessary for the mainte- 

 nance of a fishery is regulation to 

 permit adequate escapement of the 

 best spawning stock. 



Unnatural conditions exist today 

 in most of the salmon-spaw^ning 

 streams of the Pacific Coast States 

 and in many of the streams of Brit- 

 ish Columbia and Alaska. These 

 conditions have been discussed: 

 dams and pollution, denudation of 

 watersheds, irrigation diversions. 

 These and other conditions have 

 created blocks to upstream and 

 downstream migrations of salmon, 

 have destroyed or made unsuitable 

 and inaccessible hundreds of miles 

 of spawning area. These projects 

 have interrupted the finely balanced 

 timing of the salmon on their 

 spawning migrations, and, regard- 

 less of man's ingenuity in mitigat- 

 ing the harmful effects of a dam 

 (for instance, by the inclusion of 

 fish-passage facilities), the salmon 

 may still be delayed too long to ar- 

 rive at the spawning area during the 

 period of desirable water tempera- 

 tures. 



The salmon hatchery often, but 

 not always, can substitute in part 

 for natural reproduction lost by rea- 

 son of man's activities. The pro- 

 gram on the Columbia River, for 



example, includes salmon-salvage 

 projects of unprecedented scope in- 

 volving the transfer of very large 

 runs of salmon to other than their 

 natal tributaries; it also includes 

 the further development of salmon 

 populations in the lower-river trib- 

 utaries to compensate in part for the 

 anticipated loss of major portions 

 of up-river races by reason of mid- 

 dle-river dams constructed and 

 planned. 



In the first instance, occasioned by 

 the construction of Grand Coulee 

 Dam, dependence was placed upon 

 the instinct of salmon to return to 

 the stream in which they were born 

 or in which they spent their early 

 months before migrating to the 

 ocean. This program, dependent 

 upon hatchery operations to a great 

 extent, has been particularly suc- 

 cessful. Hatchery production and 

 stocking of red (blueback) salmon 

 can be directly correlated with the 

 tremendously increased runs of this 

 species returning as adults. 



The lower Columbia River pro- 

 gram has not yet proved successful, 

 but there is every indication that 

 the clearance of streams (to permit 

 greater utilization of spawning and 

 rearing areas) and hatchery stock- 

 ing will result in maximum produc- 

 tion in the lower river tributaries 

 that will largely replace loss of up- 

 stream production. 



Studies of the results of hatchery 

 production on the Sacramento River 

 in California have revealed the 

 major contribution of the hatchery 

 jH-oduct directly to the fishermen. 

 (). B. Cope and D. W. Slater (un- 

 publislied report) state that hatch- 

 erv fish released from the Coleman 



38 



