If this ia compared with the area from 160 to 170 E, which lies adjacent on the west, 

 there is a slight increase in black tuna and a sharp decline in yellowfin. There appears to be 

 somewhat of a tendency to decrease in the case of bigeye tuna, but there is no great difference, 

 the spearfish catch rate has dropped by half, and the albacore catch rate is rather conspicuously 



GO 



lower. Connpared with the area of 30 to 35 N, adjacent on the south, both black tuna and 

 yellowfin are extremely scarce, but the bigeye catch rates show quite equal values. The albacore 

 catch rate is somewhat higher in this sea area, but the difference is not as marked as that be- 

 tween this sea area and the area to the west of it. Spearfishes are scarce in both sea areas, but 

 the decline is somewhat more conspicuous in this area. 



longitude. 



The following table shows fishing conditions within the area by sections of 2 of 



Table 107. --Fishing conditions by sections (35 to 40 

 N. . 170°to 180° E.) 



The bigeye catch rates are somewhat lower in the central section, and higher at the 

 eastern and western extremities. In general albacore catch rates are high in the west and low in 

 the east, with a maximum catch rate of 10.6 in the section from 172 to 174 E. The spearfish 

 catch is so small as to be of no great importance, bat although it is difficult to perceive any local 

 differences in fishing conditions for striped marlin, the broadbill appear generally to have higher 

 catch rates in the west and lower in the east. A remarkably low catch rate for sharks in the 

 section fronn 174 to 176 E. is indicated, but elsewhere they generally show uniform vadues. 



180° E 



o o 



When these conditions are connparea with those in the area of 30 to 35 N. 



170° to 



a very similar trend for bigeye tuna is indicated. In general albacore caitch rates are 

 higher in this sea area, but in both areas roughly the same trend of higher rates in the west and 

 lower rates in the east can be detected. It is difficult to recognize any marked fluctuations in 

 the case of spearfishes and sharks. These facts indicate that the two sea areas have the same 

 characteristics as fishing grounds. 



The local variations in fishing conditions from north to south have been shown in table 

 108 by dividing the cirea into sections of 1 of latitude. 



From the table it is clear that the bigeye catch rates aie high in the south and 

 gradually decrease toward the northward. In the case of the albacore, on the contrary, the trend 

 is for high rates in the north and lower in the south, but this trend is not as regular as in the case 

 of the bigeye. For the spearfishes no definite trend CEin be detected, but the sharks clearly show 

 higher rates in the south and lower rates in the north, just as do the bigeye tuna. 



133 



