BRISTOL BAY AND ALASKA PENINSULA SALMON STATISTICS 



79 



The best measure of the catch per unit of fishing effort that we have been able 

 to devise is the catch per trap per days of fishing per week; that is to say, we have 

 taken as our unit of fishing effort one trap fishing one day per week throughout the 

 season, and to secure the catch per unit of effort have divided the total catch for 

 the season by the product of the number of traps and the number of days of fishing 

 per week. This makes the necessary adjustment for the effect of the decline in the 

 number of days per week during which fishing is permitted but does not take into 

 account any changes that may have occurred in the effectiveness of traps. 



Figure 13 shows the changes this measure of the catch per unit of effort has 

 undergone. Although there have been wide fluctuations the general trend has been 

 downward, and there can be no doubt that the actual abundance of fish has decreased 

 in much the same proportion. The present yield approximates two-thirds that 

 obtained in the earty years of this fishery. It will be noted that the greater number 

 of traps employed between 1914 and 1919 is reflected in the smaller yield per unit of 



f^ <o 



C\(K)>'O(b'^«0 0) 



(M 1.5 > l<) (0 f^ 



0> ^ 



v. >. ^ 



Fig. 13.— Catch o( red salmon at Nelson Lagoon per unit of fishing eflort. (See test for explanation) 



fishing effort, an effect that may be ascribed (in part, at least) to competition between 

 the units of gear. The decreased abimdance indicated by the yield per unit of effort 

 does not appear to be so marked as that indicated by the decline in total yield, 

 although the two are of the same order of magnitude. Furthermore there is a general 

 impression current that the fishery is even more seriously depleted than is indicated 

 by either of these measures of abundance. It appears fairly clear that neither the 

 total catch nor the catch on the basis of the unit of effort is entirely satisfactory as 

 a measure of the actual abundance. However, both indicate serious depletion, and 

 the future will show whether the present greatly reduced fishing effort will permit 

 the recovery of the run into Nelson River to something like its original proportions. 



ALEUTIAN ISLANDS • 



Table 8 presents the data on the salmon catch made in the numerous localities 

 of the Aleutian Islands from which reports have been received. The data are so 

 scattered that it is useless to try to determine whether the changes in catches have 



