14. Area of 30° to 35° N. , 



150° to 180° E. 



This sea area ia for the moat part under the direct influence of the North Pacific 

 Current (the name given to that part of the Kuroahio which leavea Japaneae watera and flowa 

 eastward), and in the northern part of the area the currents always flow to the eastward. In the 

 southern part of the area a countercurrent branches off from the North Pacific Current and flows 

 approxinnately southeastward. The subtropical line of convergence, as haa already been atated, 

 Vciries in position with the season, and in the summer it tends to move north, running east and 

 west at about the line of 30 N. latitude. In the winter it moves to the southwaird. Consequently, 

 it is said that in the summer along the southern border of the sea area great gyrals are formed 

 here and there by the countercurrents branching off to southeastward from the North Pacific 

 Current auid currents branching off to the northwestward from the North Equatorial Current. 



The vertical distribution of water temperatures and salinities is comparative uniform, 



the isotherms generally paralleling the parallels of latitude. Around February and March, when 



o 

 the winter water temperatures have reached their minimum, the 16 C. isotherm runs east and 



o 

 west at approximately the northern boundary of this sea area, while the 20 C. isotherm appeal's 



at the parallel of 30 N. In aumnner the surface water temperature over the whole sea airea ia 



o o o o o 



about 27 C. with 22 to 23 C. at the 50-meter level, and 20 to 21 C. at 100 metera. 



This sea area is well known as an albacore ground, and many boats fished there 

 around 1935, but thereafter, as the yellowfin grounds in the equatorial region were developed, 

 the number of vessels operating in this region declined markedly. However, because of the 

 prohibition on fishing in the South Seas after the war, the vessels fishing in these grounds again 

 increased jind a rather large catch was produced. 



The season is in the winter, with the nnain fishing season from Decennber to 

 February. Albacore are most numerous in the catch, but considerable numbers of broadbill 

 are taken at the beginning of the fishing season. The catch of other species of tuna ia generally 

 almost vestigial, but spearfishes are rather abundant. 



As was stated, the fishing season is during the winter and throughout the whole fishing 

 season the west winds blow strongly and continuously, meiking operations difficult, and ship- 

 wrecks are frequent so that although the catch is large it is difficult to characterize this as a 

 superior fishing ground because of the climate. 



In the following discussion this area has been divided into three parts of 10 of 

 longitude each, amd the fishing conditions within each of these sections are discussed in general. 



(a) 150 to 160° E. longitude 



The following table summarizes data from past investigations in this section. 



o / o 



Table 86. --Fiahine conditions between 150 and 160 



E. (30 to 35° N. ) 



The overall total catch rate ia allghtly over 5.8, with albacore making up alightly 

 under 83 percent of the catch. The catch ratea for bigeye tuna and apearfiahea are 0.45 and 0.52 



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