6 U. S. BUREAU OF FISHERIES 



of the banks from the markets. The proportion of spawners is high 

 on the more distant banks but almost nonexistent on the near-by 

 banks. There appears to be such active interchange as would render 

 regulations applied to one bank effective on all. 



It has, therefore, become of pai-amount importance to discover 

 how far the effects of regulation are localized, for each area must 

 bear the burden of its own regeneration. The commission has, 

 therefore, carefully and laboriously collected statistics regarding the 

 effect of the close season on the several main areas of the fishery. 

 The closure being from November 16 to the following February 15, 

 it has affected directly the fisheries at that time taking place. These 

 were along the eastern side of the Gulf of Alaska, between Cape St. 

 Elias and Cape Spencer. Here there has been prevented a very 

 considerable fall, winter, and spring catch of mature fish. In con- 

 trast to this, the fishery on the older more depleted banks south of 

 Dixon Entrance has for years been a summer fishery, and, accord- 

 ingly, the amount of the catch eliminated has been very small. At 

 the time of adoption of the present treaty the newer, less depleted 

 banks to the farther west of the Gulf of Alaska did not have a 

 fishery of any magnitude, but since then a very considerable summer 

 or open-season fishery has been developed. The close season has 

 mainly affected, therefore, one area — that on the eastern side of the 

 Gulf of Alaska. 



Examination of catches on these affected grounds has shown that 

 the fish protected were largely fish collected there for spawning, 

 which is well known. It is, therefore, evident from these facts that: 

 the close season has been operative almost entirely upon the fish of a 

 given region and upon a single category of these fish, facts that 

 should be considered in connection with the independence of the 

 various stocks of halibut. 



The commission finds that the fish thus protected by the closure 

 were exposed to fishing that was increased in intensity during the 

 open season, and, consequently, the abundance on the banks has 

 undergone a further decline due to progressive depletion. 



Tagging experiments with the spawning fish on the banks thus 

 most affected — those on the eastern side of the Gulf of Alaska — 

 showed that a considerable migration occurred to the westward as far 

 as Portlock Bank, where many of the tags were recovered. There, 

 fishing during the open season has increased enormously during the 

 three years that have elapsed since the close season has been in effect, 

 sufficient to more than offset the decline in the winter fishery on 

 the other banks. But this increase has not been due to any increase 

 in numbers of fish, for the intensification of the Portlock fishery has 

 led to a rapid fall in yield per unit of gear fished, from 160 to 100 

 pounds per " skate," and these western banks are not " holding up." If 

 further proof were required that this enormous increase of the fishery 

 on Portlock is not due to the presence of more fish there, it will be 

 remembered that halibut are on the average considerably more than 

 5 years of age when they first come into the commercial size, and 

 that the great increase in catch was, therefore, from the preexisting 

 stock. 



The same increase in the open season total catch is obvious on the 

 banks referred to as most affected. This increase, too, was due to 



