SALMON RUNS OP THE COLUMBIA RIVER IN 1938 



131 



reasonably certain that, at least for the spring run of chinooks on the Columbia, the 

 escapement is well below the level that would provide the maximum sustained yield. 

 Such regulations and restrictions as have been imposed upon the Columbia River 

 salmon fisheries apparently have very little effect insofar as they may act to reduce 

 the intensity of fishing and provide a greater escapement of breeding fish to the spawn- 

 ing grounds. It is to be noted that in the lower river the peaks of both spring and 

 fall runs come within the spring open season so that, insofar as the fishery in the lower 

 river is concerned, the main portions of both runs are exposed to the full force of the 

 exploitation. There is the weekly closed period from C pm. Saturday to 6 pm. Sunday 

 that is in force during the spring fishing season, May 1 to August 25, but it has already 

 been shown that this has little value from the standpoint of conservation; its chief 

 effect being to spread the fishery out over a longer stretch of the river. Again it has 

 been shown that whatever effect the closed season, August 25 to September 10, may 

 have in increasing the escapement through the lower river, it is largely offset by the 

 intensive fishery that exists during September and October above Bonneville Dam. 

 In a larger way this closed season acts much the same as does the weekly closed 

 period, and chiefly tends to distribute the fishery over a wider area without materially 

 increasing the breeding population. The effect of the closed season may be seen by 

 examining table 19, which is a diagram representing the passage of a series of stocks of 



Table 19. — Effrct of a two-week closed period on the stocks of 

 fish passing up the river at the assumed rate 



[Lctiers represent stocks of fish] 



Note.— Bold-face letters represent closed period. 



fish through the fishing district at the rate we have assumed to hold. It is obvious 

 from tliis diagram that there is no stock of fish that is wholly protected from exploita- 

 tion by the closed season. For example, stock C is only protected by the closed season 

 from exploitation in Zone 6; stock D is protected in Zones 3 to 6; stock E in Zones 

 1 to 5; and stock F in Zones 1 and 2 only. But, on the other hand, stock C is open to 

 the very intensive exploitation below Bonnevdle just before the closed season, and 

 stock D to the fishery in Zones 1 and 2 where a very large part of the total catch is 

 made during the week just before the closed season. Stock E, however, is completely 

 protected from the fishery below Bonneville but is exposed immediately after the 

 closed season to the much intensified fishery above Bonneville. Stock F is protected 



