During the season of southwesterly winds the sea is generally very calm. However, in the typhoon season the paths of the storms occasionally cross this sea area. Caution is necessary, particularly toward the beginning and end of the typhoon season, for at this time many typhoons cross the northern part of the area. During the season of northeasterlies strong winds blow continuously, the seas are high, and it is occasionally difficult for fishing boats to operate. Wind and seas are particularly high off Annam, making operations by small boats difficult. The waters off Luzon are generally calm. The history of the development of the tuna longline fishery in this area is so closely tied up with that of the tuna fishery at Takao that they may be said to be the same thing. The tuna longline fishery based at Takao, which started around 1913 under the aegis of the former Formosa Government-general, developed year after year with the South China Sea as its principal fishing ground. At first sailing vessels were used, but very soon all the boats were powered, beginning with vessels of about 20 horsepower and gradually increasing in size with the years until many vessels of 100 tons and 200 horsepower were being constructed. In 1936 the number of vessels operating had increased to about 300. The fishing grounds were gradually extended to the southward from the southern portion of the Formosa Strait and the whole South China Sea came within the operating area. The boats then began going farther into the Sulu Sea, Celebes Sea, and East Philippine Sea regions, and before the war the catch had surpassed the value of 15 million yen per year. The fishing season is for the most part during the season of northeasterly winds. Vessels which had been docked and overhauled during the typhoon season gradually go into operation from the latter part of September on acid ordinarily continue fishing until about May of the following year. However, around June to August a fishery for sailfish with the gear called barennawa is carried on, so even during the typhoon season fishing does not stop altogether. Beginning in 1935 there was a rapid development of the black tuna fishery and its fishing season was from March to early June. As it became known that many black marlin could be taken during the southwesterlies the latter years of the Japanese occupation of Formosa saw longline fishing carried on almost throughout the year. The following is a general outline of fishing seasons and the fishing situation in the South China Sea. At the beginning of the season around September Sonne catches, principally of yellowfin, were made in the southeastern portion of the area, that is, the part adjacent to the Sulu Sea, and with the passage of time fishing gradually became active in the vicinity of Steward Bank and Macclesfield Bank, after which the fishing suddenly became good all over the whole area. However, around January to March, when a conspicuous cold water zone appears in the central portion of the area, as already noted, fishing becomes generally poorer in this central area. Toward the end of the fishing season the center of the fishing grounds shifts from the vicinity of Dangerous Ground to the waters off Cochin China and Annam, and at this time the fishing for spearfishes becomes active from this area to the vicinity of Hainan I. The principal species in the catch is the yellowfin. Data from investigations covering the whole year indicate that about 90 percent of the fish in the total tuna and spearfish catch of the longline fishery in this region are yellowfin, the remaining 10 percent being bigeye tuna () and spearfishes. However, this is in the overall view and as was noted earlier, the situation is completely different as regards the so-called barennawa, which fishes especial for bigeye tuna and sailfish or in the case of the fishery between the waters of Annam and the Hainan I. region, where spearfishes are the main objective. The foregoing is the situation which obtained before the development of the black tuna fishery in recent years. The main component of the catch during the black tuna season was, it goes without saying, black tuna. In recent years the black marlin has followed the black tuna in becoming abundant in the catch, and taking Formosa as a whole it appears that in recent years the number of tunas and the number of spearfishes in the catch have been almost equal (see table 7). The first captures of black tuna in this area were in 1935. Before that year there are no records of this species being taken, but it is questionable whether they were completely absent. Questioning of fishermen at Takao at that time revealed that every year at about the same 61