As the table shows, the catch rates in 1950 were nearly three 

 times those of the preceding and following years. There are also violent 

 fluctuations in catch rates within unit areas, as shown in table 17. 



Table 1 7. --Fluctuations in the catch rates by unit areas 

 /frequency of coefficients of variation/ 



The oceanographic conditions have changed considerably since 

 November. In November there was a clearly marked gyre, with the 

 fishing grounds developing in its middle, but in December this gyre has 

 become unclear and displaced to the southeast (see the supplementary 

 chart for November). 



The albacore taken in this area, as shown in table 18, are all 

 extraordinarily large fish. 



Table 18. --Albacore size composition in the Okinotorishima area 

 by years, 1949-51. Weights (W) in ( ) are in kan = 8. 27 lbs. 



As can be seen from the table, the fish are extraordinarily large, 

 with a great difference in size as compared with those from the North 

 Pacific fishing grounds. South of the Subtropical Convergence, at about 

 the same longitude, the density of distribution of albacore is generally 

 low and the fish are generally large, apparently of about the same size 

 as the fish taken on this ground. 



4. South Seas 



The catch rates are generally up as compared with November. 

 As has already been stated, there is a scattering of unit areas with catch 

 rates of 1.0 or greater. 



53 



