130 FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



landings per week derived from the figures given in table 17, and shown in the 

 following statement: 



Total number of deliveries per week in Zones 1 and 2 during June and July 



Week ending Deliveries 



June 11 1,551 



June 18 2,008 



June 25 2, 229 



July 2 2,283 



July 9 2,692 



July 16 2,647 



July 23 2,424 



July 30 3,013 



It is shown by the preceding statement that the number of deliveries practically 

 doubles during the months of June and July — an increase in fishing effort that could 

 readily account for the fact that the count at Bonneville Dam does not increase, 

 although there is better than a fourfold increase in the number of fish taken in the 

 fishery in Zones 1 and 2. 



In this connection it has been of interest to determine something of the relation- 

 ship that exists between the abundance of fish as measured by the average poundage 

 per delivery and the number of deliveries. The number of deliveries may be taken as 

 a fair measure of the number of men fishing. We have, therefore, taken these two 

 scries of values from table 17 and calculated the coefficient of correlation. This 

 proved to be +0.75. The interpretation is quite clear that the abundance of fish, as 

 shown by the size of the individual catches, is an important factor in determining the 

 number of fishermen that will fish. 



INTENSITY OF FISHING IN GENERAL 



The runs of chinook salmon considerably outweigh in importance and value the 

 runs of all other species in the Columbia River fishery combined. Of the entire run 

 the part that enters the river during spring and early summer, April to July inclusive, 

 is the most valuable on account of the fine quality of the fish. This part of the run, 

 perhaps more than any other, has been adversely affected by the reduction of spawn- 

 ing areas and localities suitable for the rearing of the young fish that has attended the 

 utilization of the water resources in the headwaters, especially for power and irriga- 

 tion. Since the salmon industry began on the Columbia River the chinook has been 

 the mainstay of the fishery and the most relentless exploitation has fallen upon the 

 spring run. 



It has been shown above that the present intensity of fishing is such that, in 

 1938, over SO percent of the spring run and between 60 and 70 percent of the main 

 fall run of chinook salmon were taken in the commercial fishery. In this connection 

 it is pertinent to recall that in the regulation of the Alaska salmon fisheries the Federal 

 Government, acting through the Fish and Wildlife Service, has adopted the principle 

 that the escapement should be not less than 50 percent of the entire run. There are 

 sound theoretical grounds for thinking that the maximum sustained yield of the sal- 

 mon fisheries can be maintained with an escapement of this order of magnitude, and 

 the practical results obtained with the Alaska fisheries support this view. It seems 



