9/ 



group hypothesized by Uda— . Most of the large-sized vessels which put 



out with the objective of fishing albacore have operated in this region, 

 particularly between 1925 and 1935, when it was the main fishing ground 

 for the larger vessels. Around 1936 the yellowfin grounds of the South 

 Seas were opened up, and thereafter the number of vessels operating in 

 this region greatly dinninished. After the war, when the fishing grounds 

 were limited by the so-called MacArthur Line, the number of vessels 

 operating in this region again increased, but with the disappearance of 

 the MacArthur Line there was another marked decrease in the number 

 of vessels operating. 



In this sea area the fishing is already quite good in November; 

 the catch rates further rise in December, and east of 165 E. almost all 

 of the unit areas show catch rates above 3.0. The catch rates for unit 

 areas are highest in the north, with the majority above 34 N. showing 

 rates above 5.0. Along the southern edge of this area, contrary to the 

 case of the areas west of 160 E. , the catch rates are somewhat lower 

 than the overall average for the area. 



Table 11 shows the frequency distribution of coefficients of varia- 

 tion for six divisions of this area made by dividing it into east and west 

 halves of 10 of longitude each and further dividing these into three parts 

 of 3 of latitude each. 



Table 11. --Variation in fishing conditions between 160 E. and 

 180 in December 



Just as in the waters west of 160 E. , the variation in fishing con- 

 ditions is snnall in the south, and this is judged to indicate fairly stable 

 conditions. Conditions in the most northern part of the section of 170°E. 

 to 180 are not well known because of the paucity of data, but it is clear 



9/ 



- Uda, Michitaka. Bull. Jap. Soc. Sci. Fish., Vol. 5., No. 5. 



47 



