the investigations had poor results at first and that it consequently was not understood that there 

 were excellent fishing grounds in this region was mainly the unsuitable construction of the fish- 

 ing gear. The gear in use at that time was exactly the same in construction as that used in 

 Japanese coastal waters. Consequently it was unsuited to the markedly different environment 

 afforded by the waters of this area; it is said that the branch lines were too short and did not 

 reach the level at which the tunas swim. 



Gradually measures were tciken to improve the methods of investigation, aind it was 

 made clear that this region affords excellent fishing grounds, which were thus finally brought to 

 the attention of the industry. The direct motive for the sudden development of the fishing 

 grounds of this region was the full load of yellowfin brought back in 1936 by the Hidekichi Maru 

 (90 tons) based at Misaki in Kanagawa prefecture. Stimulated by this, the large fishing boats 

 based at Misaki began competing to fish on these grounds. Some mention of the history of this 

 fishery has already been made in preceding chapters. 



Fishing ground surveys and fishing experiments in this region were carried on by the 

 former South Seas Government-General Fisheries Experiment Station with its research vessels 

 Hakuo Maru and Zuiho Maru. Later when this region was being exploited as a longlining ground 

 for tuna, principally yellowfin, a large nunnber of prefectural reseeirch vessels also operated 

 there and, as the following table shows, the data from their researches are quite abundant. 



Table 30. --Fishing conditions in the southern portion 

 of the former South Seas Mandate (0 - 

 10° N. , 130° - 170° E.) 



Note: The figure for yellowfin also includes 142 albacore. 



data. 



The situation as regards sharks is not clear because there are many omissions in the 

 However, calculations based on considerable material give a catch rate of about 1.5. 



As for the composition of the catch of tunas and spearfishes, yellowfin were most 

 numerous forming slightly under 74 percent of the whole. Spearfishes were slightly more than 

 15 percent and bigeye tuna were 11 percent. In addition a very snnall number of albacore were 

 caught, amounting to about 0.6 percent of the yellowfin. On the whole the catch rates in this 

 area are somewhat better than in the Pacific coastal waters of New Guinea or the Solomon 

 Islands, and not greatly different from those of the South China Sea or the Celebes Sea. 



There appear to be fairly conspicuous differences in the fishing conditions in 

 different parts of this region. The following table shows a comparison of fishing conditions north 

 and south of the line of 5 N. latitude. 



67 



