Qceanographic conditions 



This sea area is where the Kuroshio, flowing up along the Japanese 

 islands, turns to the east away from the islands, and consequently the cur- 

 rents are a great deal more complex than they are farther to the east. 





\ 



J55' . 





Figure Z shows the currents for the 

 period December to March, based on the 

 North Pacific Current chart, Hydrographic 

 Office Chart 603 lA. As the figure shows 

 between 35°N. and 37°30'N. , east of 145 E. , 

 the currents run almost due east. Farther 

 north the currents also trend generally to 

 the east, but they flow somewhat irregularly 

 and instances can be seen where they flow to 

 the south, to the southwest, or to the north. 

 West of 145 E. , between central Honshu 

 and the waters off Kinkazan in northeast 

 Honshu, there is a strong current flowing 

 to the northeast, with another current flow- 

 ing south along the coast. The waters south of 35 N. are the Kuroshio 

 Countercurrent area, and there we see a clockwise gyre taking in all of 

 the area from 30°N. to 35°N. , 140°E. to 145°E. An area of irregular 

 currents can be seen centered at 150 E. Farther to the south no strongly 

 marked currents can be seen. 



Figure 2. --Vector current 

 chart (based on J. H. O. 

 6031A) 



The main fishing grounds are in general on the east side of the 

 Kuroshio. The area of low catch rates running from the vicinity of 40 N. , 

 155 E. to 30 N. , 150 E. appears to correspond to the area of irregular 

 currents. 



Before the war there were regular transverse observation lines 

 running from east to west across this area, but the data for December 

 extend to only 200 miles off the coast and, therefore, there is no way of 

 knowing the overall oceanographic situation. 



Table 5 consists of data from sectional observations running from 

 Cape Nojima to northeast of Iwojima in November and December of 1949 

 and the same months of 1950. 



Figure 3a and b depicts the distribution of water temperatures and 

 salinities given in table 5. 



From this table and the figures it can be seen that between 32 N. 

 o 

 and 34 N. water of high tennperature reaches fairly great depths, and this 



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