BRISTOL BAY AND ALASKA PENINSULA SALMON STATISTICS 



43 



The striking drop in 1921 was an entirely different matter, however. The market 

 was glutted with tlie cheaper grades held over from the previous two or three years, 

 and in consequence no serious effort was made to pack pinks and chums in south- 

 eastern Alaska; the small total pack of 1921 was due almost entirely to this cause. 

 In the following year the market recovered and operations were resumed in south- 

 eastern Alaska. For four years the pack fluctuated slightly around 4,500,000 and 

 5,000,000, rising sharply to a new maximum in 1926, followed by the remarkable 

 drop in 1927. This rise and fall were shown, in general, by all species and in all 

 districts; there was no marked change in the intensity of fishing, and the conclusion 

 seems warranted that these fluctuations were caused primarily by biological factors. 



Fig. 2.— Total pack of canned salmon in Alaska 



Our knowledge of these factors is too meager at present to warrant speculation 

 as to their nature, but it seems safe to say that the wide fluctuations that have taken 

 place since 1918 (although in part economic) are associated with the onset of deple- 

 tion, or at least with the development of the fishery to the point of maximum produc- 

 tivity. This hypothetical point of maximum productivity may be defined as the 

 number of fish that may be taken from the resource without impairing it. It will 

 vary from year to year and can never be defined sharply, although it seems probable 

 that ultimately we may be able to define it rather broadly. Any development of the 

 fishery beyond the point of maximum productivity must lead inevitably to depletion 

 and must be guarded against carefully. The conclusion that such wide fluctuations 

 indicate that the fishery has reached its limit seems warranted from the following 

 considerations: Under natural conditions, unaffected by exploitation, the abundance 

 of fish in any fishery resource is certain to fluctuate rather widely, due to varying 



