continues moving to the southwest and it seems to be located in the 

 vicinity of 30°N. , 140°E. As a result, in the vicinity of 140 E. the 

 zone of high catch rates appears to be pushed from 30 N. southward 

 to the vicinity of 25 N. to 27 N. 



Uda — , studying the fishing conditions in 1935 and 1936, hypothe- 

 sized that the albacore east of 150 E. may have, after moving south to 

 the north side of the Subtropical Convergence, migrated west along to the 

 line of 150 E. and then turned north. However, when we consider the 

 movements of these albacore which have migrated south to the north side 

 of the Subtropical Convergence in terms of catch rates, we may wonder 

 whether they do not turn directly back north without moving west. 



Judging from the fact that we can detect no tendency for the catch 

 rates to decline in the areas far off to the east, and from the fact that 



there is. on the contrary, a tendency for the catch rates to rise simul- 



o o 



tajieously in the east and west between 30 N. and 32 N. in April as com- 

 pared with March, it is thought that the albacore which migrated south in 

 the form of an elongated band and stopped on the north side of the Conver- 

 gence directly enter upon their northward migration in that same form. 



As for the size composition, the pattern of larger fish on the south 

 side and smaller fish on the north side which was seen during the period 

 of southward migration now becomes unclear (see table 1), 



Table 1. --Length composition (%) of albacore landed from the North 

 Pacific ground in April, Mean weight in kan (8,27 lbs.) 



There is still room for investigation of the question of whether or 

 not this tendency is a phenonnenon that is limited to the southern extremity 

 of the fishing ground. It still appears that the fish are larger off to the 

 eastward. Between 140 E. and 150 E. medium-sized albacore of about 

 3 keui /25 lbs. / predominate overwhelmingly. Between 28 N. and 30 N. 

 the size composition shows practically no cheinge from the preceding month. 



10/ 



— Uda, Michitaka and Hidematsu Tokunaga. 1934. Relationship 



between albacore fishing conditions and oceanographic conditions. Bull. 



Jap. Soc. Sci. Fish., Vol. 5, No. 5. 



114 



