In October, in all areas, the major part of the catch was fish of 

 85 to 95 cm. (4. I kan weight), but in Novennber there was a general and 

 conspicuous increase in fish of the 75 to 85 cm. length class (2. 8 kan). 

 Furthermore, the tendency mentioned for October for the fish to be 

 smaller in the south ajid larger in the north, as well as smaller in the 

 west and larger in the east, is extremely clearly shown in table 2. 



In October the fishing conditions between 150 E. and 160 E. were 

 remarkably poor compared with areas to the east and west, but in Novem- 

 ber, although an area of rather low catch rates can be seen in the central 

 part, the fishing conditions had picked up considerably over the whole area. 

 From what is shown in the chart, it looks as if this change in the fishing 

 conditions was brought about by a movement of the schools in from the 

 east and the west, particularly from the east. However considering the 

 size of the fish in the catch, the changes are gradual, just as they were 

 in October, and with the amount of data available it is not possible to 

 reach any conclusions as to whether the schools originated in the areas 

 to the east or to the west. 



Looking at the shifts in the fishing conditions fronn December on, 



it is thought that the schools in the extreme western portion (west of 150 E.) 



o / o 



gradually nnove toward the west, while those east of 150 E. or loO E. simply 



keep moving south. 



2. Areas of the Middle Latitudes 



Considering the middle -latitude sea areas as a whole, data are 

 s< 



high. 



very scarce and the overall situation is not clear. Although the data are 

 inadequate, between 24 N. and 30 N. on 165 E. the catch rates are rather 



The so-called Okinotorishinna fishing ground, which in October was 

 showing signs of developing, is very clearly mcirked in this month, and fish- 

 ing is active there. This fishing ground appears in complete isolation, with 

 its center at 20°N. to 25°N. , 1320E. to 137°E. Stated very broadly, this 

 fishing ground is surrounded on three sides, on the south, west, and north, 

 by the North Equatorial Current and the Kuroshio, while on the east it is 

 covered by the Ogasawara Current, flowing north along the Ogasawaras 

 aind Marianas. In the waters where this fishing ground is formed the cur- 

 rents are as shown in the supplementary chart* and the direction of flow 

 is locally complicated, however, in general it is a circular flow in a 



* From North Pacific Current Chart No. 603 1-D. 



24 



