BRISTOL BAY AND ALASKA PENINSULA SALMON STATISTICS 95 



pinks we are inclined to the opinion that there was some marked change in the conduct 

 of the fishery. Leaving 1927 out of consideration, there would still appear to be some 

 slight fall in the yield, which possibly may be referred to depletion. It is very inter- 

 esting to note, however, that the discontinuance of the fishery during the years 1919 

 to 1921, inclusive (if, indeed, our records are reliable), had no appreciable effect in 

 increasing the future runs. 



POPOF STRAIT 



The most important fishery in the Shumagin district is prosecuted in Popof 

 Strait, where several extremely productive traps are situated. Our records show that 

 traps were driven here first in 1919, but it was not until 1922 that the production 

 increased markedly. Doubtless this was due to improvements made in the location 

 and contruction of the traps. The tagging experiments of 1922 and 1923 showed that 

 these traps caught large numbers of the fish bound for Ikatan and Morzhovoi Bays 

 and thence for Bristol Bay. With this in mind we have investigated the correlation 

 shown between the catches in Popof Strait and those at Ikatan and in Bristol Bay 

 for the years 1922 to 1927, inclusive. For this purpose we have used Spearman's 

 coefficient of correlation (p), which is recommended for cases in which the number 

 of items is small. While this method is not as accurate as the better-known formula 

 of Pearson (r) it is as reliable a method as is justified by the available data. The 

 following values of p have been determined: 



Popof Strait and Ikatan +0. 657 ±0. 164 



Popof Strait and Bristol Bay +. 600 ±. 184 



A high degree of correlation is indicated, as would be expected from our knowledge 

 of the routes of migration. 



On account of the marked change in the effectiveness of the fishery, which took 

 place in 1922, and the short series of years since that event we do not feel justified 

 in making any additional analyses of the data. 



RED COVE 



This fishery has drawn chiefly upon a small run of red salmon that enters a 

 stream flowing into Red Cove. As is the case in most such small fisheries, doubtless 

 it has been prosecuted intensely, and our data, although not extensive, indicate a 

 general decline in the yield, which may safely be ascribed to depletion. 



