6. Southern part of former South Seas Mandate (0 to 10 N. 



130° to 170° E. 



) 



The current syatems of this area fronn south to north are the South Equatorial 

 Current, the Equatorial Countercurrent, and the North Equatorial Current. The boundary between 

 the South Equatorial Current and the Equatorial Countercurrent is from the vicinity of the 

 Equator to about 3 N. latitude and the boundary between the Equatorial Countercurrent and the 

 North Equatoriad Current is between 5 and 8 N, latitude. The boundaries between these cur- 

 rents are not straight lines but change with the topography and the season, however, in general 

 they parallel the parallels of latitude. They are generally pushed to the southward during the 

 season of northeast winds and tend more or less northward during the season of southwesterly 

 winds. The pattern of the current in the vicinity of 130 E. longitude, that is, at the western 

 extremity of this area, is affected by the proximity to land and is remarkably complex. 



The following table shows nnonthly changes in water tennperatures based on data from 

 observations made at fixed stations by the former South Seas Governnnent-General Fisheries 

 Experiment Station in the vicinity of 7 10' N,, 134 30' E. 



Table 29. --Water temperatures for each month 

 (7° 10' N., 134° 30" E.) 



Surface water temperatures are high in May and June and in October and November, 

 low in February and March, and they also drop somewhat in August. The 50-meter level shows 

 high temperatures above 29 C. in July and September and October, while in January and 

 February the temperatures at this level are lowered to 27. 5 C. At the 100-meter level the 

 water temperature rises above 26 C. in August and in October, and in February it reaches its 

 lowest point with readings between 22 C. and 23 C. Water color is I or II on Forel's scale and 

 transparencies are 30 to 40 meters. 



During the season of southerly winds the sea is extrennely calm, and this is called the 

 calm season. During the season of northeasterly winds the wind cind waves sometimes rise 

 rather high cuid it appears that at times difficulty is experienced in fishing. 



After the South Sea islands in this region became a Japanese mandate, attention was 

 first given to the skipjack grounds and efforts were made to develop them. As a result skipjack 

 fisheries were fairly well developed on the grounds around the coasts of the various islands. 

 However, the bait problem was not solved and the fishery was always in difficulties because of the 

 uncertain bait supply and economic factors such as the falling price of the product (mainly dried 

 skipjack). 



The former South Seas Government-General, with the support of the Ministry of 

 Agriculture and Forestry, undertook the investigation ajud development of tuna longlinlng grounds 

 in this region, but for a long time they attracted very little attention. It appears that the reason 



66 



