250 



300 



(in) 



10 20 30 40 50 60 TO 80 90 100 ISO 200 (M) 



Figure 4a. --Water temperatures on a 200- 

 mile section due east of Inubozaiki, De- 

 cember 8-9, 1938. 



(TTi) 10 20 30 40 50 60 TO 80 90 100 



Figure 4b. Water temperatures on a 200 

 mile section due east of Inubozciki, De- 

 cember 29-30, 1938. 



200 IM) 



In Decennber the 

 southern extremity of the 

 albacore fishing grounds, 

 as has been shown in the 

 figures, is at 27 N. , and 

 to the northward the grounds 

 extend to 39 N. Consequently, 

 this means that fishing grounds 

 appear within the Kuroshio as 

 well as to the north and south 

 of it. If the oceanographic 

 observation data and the data 

 on the fishing conditions were 

 for the same year, it would 

 probably be possible to make 

 some observations concern- 

 ing the relationship between 

 currents and fishing grounds, 

 but, unfortunately, at present 

 we do not have any data of 

 this sort. 



Table 6a and b shows 



the relationship between the 



surface water temperature 



and the catch rate for this 



area, which is divided into 

 o o 



one part from 30 N. to 35 N. 



o 

 and another part from 35 N. 



to 40°N. 



Stated very generally, 

 table 6a represents the Kuro- 

 •hio Countercurrent, and b 

 represents the main Kuroshio 



and the waters to the north of 



it. South of 35°N. the catch 



rates are highest within the range of water temperatures of 20 to 21 C. , 



followed by the rates at water temperates of 21 to 22 C. Below that the 



catch rates drop as the water temperatures fall. In the areas north of 

 o o o 



35 N. the highest catch rates are at water temperatures of 17 to 18 C., 



followed by those areas having water temperatures of 18 to 19 C. The 



catch rates are lower where the water temperatures are above or below 



this range. South of 35 N. the average temperature at which catches are 



40 



