It is only very recently that this area has attracted notice as a tuna longline fishing 

 ground. In the eau-ly years of the Showa Era (the late ZO'a ) the research vessel Shunkai Maru 

 (180 tons) of the former Formosa Government General made some surveys in the northern part 

 of the area, but the results were extremely poor, the area was ticketed as being alnnost value- 

 less as a fishing ground, and it was thenceforth neglected. According to the commonly prevail- 

 ing opinion at that time, an area like this one without reefs or shoals, and indeed one of the two 

 deepest parts of the world's oceans, was adjudged to be unsuitable for the establishment of the 

 tuna longline fishery. 



The investigations of the Shunkai Maru were made in February. The investigations of 

 the Shonan Maxu in this sea area were undertjjcen from June to Septennber of 1937. As a result 

 of the work of the Shonan Maru it became known that this area was an extraordinarily good fish- 

 ing ground, the attention of commercial operators was suddenly attracted, and a constant pro- 

 cession of vessels based at Takao began fishing there. In the beginning the principal object of 

 the fishing in the northern portion was the black marlin and the main catch in the southern portion 

 was yellowfin tuna. Beginning in the following year (1938), it gradually became known that the 

 northern portion was an extremely fine black tuna ground and there was a sudden increase in the 

 number of vessels fishing there for this species. The fishing season for black tuna, as was 

 stated in the section on the South China Sea, is from the latter part of March to early June. The 

 main fishing season for black marlin is from April to August, the fishing ground for this species 

 being generally slightly farther off shore than that for the black tuna. Consequently, although the 

 positions of the fishing grounds differed somewhat, the northern part of this sea area was judged 

 to have ample value as a tuna longline fishing ground fronn April to around August to September. 

 After September, that is with the start of the season of northeasterly winds, the fishing appears 

 to deteriorate sharply, but the details of this are not clear because of the paucity of data. 



Because of the distance, the southern part of this area, where yellowfin were the msiin 

 catch, was not fished very much, only aji occassional large vessel having operated there. It is 

 certain that at some seasons it is an extremely good fishing ground, and it appears that in the 

 most southerly portion seasonal changes in the fishing conditions are comparatively slight. 



Most of the investigations in this cirea were made by the Shonan Maru, Shunkai Maru, 

 and Takao Maru. There are also some data from operations of the Kiyo Maru and the Zuiho Maru 

 in the southern part of the area. The data from these vcirious sources are summarized in the 

 following table to indicate fishing conditions in this region. 



Table 37. --Fishing conditions in the East Philippines 

 Sea (0 to 20° N. , 120° to 130° E. ) 



Catch rates are fairly high, nearly 6.0 . On the whole the data are scarce, and 

 there are none at all for January, October, and December, so the seasonal changes in the fish- 

 ing conditions are not well known, however, the data in the foregoing table can be divided between 

 the northeast and southwest monsoons as follows. 



74 



