In the Sulu Sea yellowfin are most numerous followed by the spearfishes, and fishing 

 proceeds throughout the year. The Celebes Sea is also an excellent fishing ground with yellowfin 

 tuna most numerous, followed by the spearfishes, of which the chief is the white marlin. The 

 fish are caught there throughout the year, but the peak of the season is during the season of 

 southwesterly winds, the fishing situation appearing to resemble that of the southernportion of 

 the East Philippine Sea. 



In the low latitudes of the Pacific, in the grounds centered along the Equator, yellow- 

 fin are very abundant, forming about 75 percent of the catch (excepting sharks). Bigeye tuna are 

 about 10 percent and spearfishes about 15 percent. Some albacore are taken, but there are ab- 

 solutely no records of black tuna being caught there.— Seasonal changes in the fishing situation 

 are slight, but in general catch rates are better during the season of southwesterlies than during 

 the season of northeasterly winds. Proceeding northward from the '-icinity of the Equator the 

 catch rates for yellowfin fall off sharply, the catch rate curve dipping to a low in the vicinity of 

 10 N. The spearfishes are most abundant in an area centered on ZO N. latitude. 



The preceding is an outline of the fishing seasons and fishing grounds in the western 

 part of the Pacific Ocean north of the Equator. In general the density of distribution of tliese 

 fishes in this area increases during the summer. However, the albacore and broadbill are more 

 abundant during the winter. From a geographical point of view, the yellowfin are very densely 

 distributed in the Equatorial Countercurrent, spearfishes are most abundant in the North Equa- 

 torial Current, and albacore are most plentiful to the north of the subtropical convergence. 

 Broadbill are also more numerous north of the subtropical convergence, but there the principal 

 zone of distribution is narrow in an east-west direction. Bigeye tuna are caught in roughly 

 equal abundance all over the whole area. The black tuna appears to occur chiefly in the area of 

 the Kuroshio. 



IV. Fishes Taken by Tuna Longline Fishery 



The tunas are among the fishes with which the Japanese are best acquainted, but 

 this is only true of tuna which has been made into sliced raw fish or served on top of rice balls. 

 There are actually few people who know what the fish look like, and even fewer who can tell one 

 species from another. Still fewer people know where and by what methods such fish are taken. 



As indicated by the number of names cited in the preceding chapter, the number of 

 species is fairly large. They all migrate extensively in the open sea and their capture is attend- 

 ed by extremely hard labor on the part of the fishermen, who sail the broad sea in small vessels 

 and do battle with the elements. 



As has been stated .previously, the greatest among the tuna fisheries is the longline 

 fishery. The principal objects of this fishery are of course the various species of tuna, but at 

 some times and places the spearfishes also have an extremely important significance. Although 

 they do not have the economic value of the other fishes, the sharks are also important in the 

 catch of this fishery. The following is a brief account of the habits and form of these fishes. 



4/ The capture of a few individuals was reported from mothership-type operations carried on 

 from June to September 1950. 



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