SALMON EUNS OF THE COLUMBIA RIVER IN 1938 105 



commercial catch. It is believed, therefore, that error in the estimates of fishing 

 intensity of chinooks, due to spawning in the tributaries that enter the Columbia 

 below Bonneville Dam, is relatively small, even during the first few weeks of the spring 

 open season. After about the middle of May it seems reasonably certain that there 

 is very little error due to this cause until at least the first of August, at which time some 

 fish that will eventually spawn in the smaller tributaries below Bonneville Dam begin 

 to enter the river. 



In none of these lower tributaries is there a large rim of spawning fish while the 

 count of fish passing Bonneville is at its peak during August and September. These 

 facts indicate clearly that, even during these months, the error in the estimate of 

 fishing intensity based on a comparison of catch with the count at Bonneville will not 

 be serious. As the season advances, however, progressively larger percentages of the 

 fish entering the river are destined to spawn in the lower tributaries. Although the 

 total number of fall fish spawning below Bonneville Dam is probably not large com- 

 pared with the number spawning above the dam, the error will tend to increase, and 

 great dependence cannot be placed on the results of the study of the late fall fish. 



Steelhead trout spawn generally throughout the accessible tributaries, but ap- 

 parently are more abundant in the upper than in the lower streams. In the case of 

 silver and chum salmon, a very large proportion of the spawning occurs in the tribu- 

 taries below Bonneville Dam, so that the ratio between the count at the dam and the 

 catch gives no reliable indication of the intensity of the fishery. 



This report deals primarily with the salmon runs of 1938 and it is to be hoped that 

 similar studies, either by this writer or by others, will be made of future runs for which 

 similar data will be available. As a part of the "frame of reference" into which are 

 placed these studies of the runs of individual years, however, it is important to pre- 

 sent something of the earlier history of these runs. This has been done in some detail 

 elsewhere (Craig 1938 4 ; Oregon State Planning Board 1938 5 ; Craig and Hacker 1940; 

 and Rich 1940b) and there is presented here only a graph showing the average annual 

 catch of each species for each 5-year period. The data for this graph have been taken 

 from Craig (1938), and recent numbers of the Pacific Fisherman Year Book. Previous 

 to 1888 there was no segregation of the salmon catch by species, but there can be no 

 doubt that chinooks formed the bulk of the catch. For the first 2 decades during which 

 the pack was segregated the chinooks formed about 80 percent of the total, and it 

 has been assumed that approximately the same percentage existed prior to 1888. No 

 attempt has been mado to estimate the catch of the other species previous to the 

 period 1890-94. The catch in pounds has been estimated from the figures for the 

 canned and mild-cured packs, which include a large part of the total. Further details 

 may be found in the several references given. 



Figure 1 shows the rapid growth of the industry during the first 2 decades after 

 its inception, a period of 35 or 40 years in which the catch of chinook salmon fluctuated 

 from about 20,000,000 to 30,000,000 pounds and a final period of some 20 years in 

 which there has been a constant decline. In all probability this decline is an indica- 

 tion of true depletion; that is, a reduction in productivity below the point that can 

 be maintained over a long period of time. The picture is complicated by the existence 

 of an extensive oceanic fishery extending from Monterey Bay to southeastern Alaska, 

 which draws heavily upon the supply of Columbia River chinooks (Rich 1941). 



' Memorandum regarding fishing in the Columbia River above and below Bonneville Dam. 16 pp., U. S. Bureau of Fish- 

 eries, Washington. (Processed.) 



« Commercial fishing operations on the Columbia River. 73 pp. Oregon State Planning Board, Portland, Oreg. (Processed.) 



