122 FISHEKY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



For the season prior to April 16 there was, of course, no catch; the estimated 

 escapement was 2,940, and the corresponding count at Rock Island was 112. The 

 percentage of the run going to the upper Columbia River was, therefore, 3.8. (All 

 of these statements and other similar ones to follow are approximations that are 

 affected by errors in the data and in the various assumptions involved. We believe, 

 however, that neither the data nor the assumptions are seriously in error so that these 

 are valid approximations.) 



During the period from April 17 to May 28, the period when the first conspicuous 

 peak of the run occurred, the catch amounted to over 1,681,000 pounds (table 1), 

 estimated as representing approximately 118,000 fish. The Bonneville count was 

 27,400, the catch above Bonneville 7,000, and the estimated escapement 20,400 

 The Rock Island count was 1,321. The ratio of catch to escapement (catch divided 

 by escapement) is 5.8:1 — in other words, it is estimated that 5.8 fish are caught for 

 every one that escapes and is available for reproduction. The percentage of the entire 

 escapement that went to Rock Island was 6.5. The catch that may be attributed to 

 the Rock Island contingent in the run is, therefore, 6.5 percent of 118,000 fish, about 

 7,650. An estimate of the poundage derived from the Rock Island run during this 

 period may also be had by taking 6.5 percent of the total weight of chinooks in the 

 catch made in the corresponding periods on the lower river. (This includes the catch 

 of the first 4 weeks in Zones 1 and 2, of the first 5 weeks in Zones 3 to 5, and of the 

 first 6 weeks in Zone 6.) The estimate of the poundage derived from the Rock Island 

 run is, therefore, 109,000 lbs. (6.5 percent of 1,681,000 pounds). 



For the period from May 29 to July 30, the total catch was 2,242,000 pounds, 

 representing an estimated 80,700 fish. The Bonneville count was only 17,900. The 

 catch above Bonneville amounted to some 1,500 fish, leaving an estimated escapement 

 of 16,400. The Rock Island count was 2,491. The ratio of catch to escapement is 

 4.9:1 — approximately 5 fish are captured for every one that escapes. The Rock 

 Island count was 15.2 percent of the estimated escapement. The catch that may be 

 attributed to the Rock Island run, therefore, is 12,300 fish of an aggregate weight of 

 341,000 pounds. 



It is to be noted especially that the Rock Island portion of the run during this 

 period constitutes over 15 percent of the total and that this is the period during which 

 the run is slack and the catch relatively poor. It is well known that this condition 

 exists each year and it is the general opinion that the populations that characterize 

 this period are the most seriously depleted of any. Certainly it is evident that they 

 are without adequate protection at the present time. By far the greater part of the 

 fish taken in the commercial fishery during these weeks is of high quality and produces 

 the finest of the Columbia River pack. The preservation of so important a part of 

 the run is obviously a matter of the highest importance. This part of the run will be 

 considered in more detail below. 



The run from July 31 to August 27 provides a large part of the total catch of 

 the spring season, but the contribution made by the Rock Island runs is relatively 

 small. The total catch for this period during 1938 was 5,640,000 pounds, representing 

 about 207,000 fish. The Bonneville count was approximately 149,600, and the catch 

 above Bonneville was 2,800, giving an estimated escapement of 147,000. The ratio 

 of catch to escapement during this period was, therefore, only 1.4:1, which was un- 

 doubtedly reduced by the increased escapement during the last 2 days of the period 

 after the fishing season closed on August 25. The Rock Island count was 1,057, which 



