season it gradually becomes more dispersed and the fishing grounds shift gradually from south to north. However, as there is sporadic fishing of black tuna at almost the same season in the waters contiguous to this area on the south and north, if the schools do move from south to north, it is in a renicirkably dispersed state. It is thought that from about the time the black tuna season ends, dense schools of black marlin migrate into the area, but we do not as yet have any concrete data concerning this fact. The basis for this supposition is, as was stated in the section on the East Philippines Sea, that between May and September dense schools of this species are seen in the North Equatorial Current and the region of the origins of the Kuroshio, and there are two or three records showing that quite a few black marlin are taken about the same time in the Yonakuni Island area. It is considered that their fishing grounds are probably farther off shore than the harpooning grounds, and as there have actually been hardly any fishing vessels operating there, nor any experimental or exploratory fishing, there are no data at all to offer as evidence. As the foregoing shows, this area has hardly been considered as a fishing ground during most of the season of southwesterly winds. The fishing ground during the northeast monsoon, both in the case of the harpoon fishery and the longline fishery, is extremely coastal in character, being limited to within 30 miles of the shore. The situation farther off shore was investigated by the Shonan Maru, Shichisei Maru (fisheries research vessel of the former Taihoku Province), and the Takao Maru, which caught considerable amounts of tunas, spearfishes, and sharks, however, it can by no means be thought to be a superior fishing ground. The waters of the Okinawan archipelago are noted as a fishing ground for sedentary skipjack rather than as a tuna ground. Nevertheless, tunas and spearfishes are taken throughout the region and certain localities are known to be outstanding longlining grounds. There are excellent grounds between Uotsuri Shima and the Miyako Archipelago and south of the main island of Okinawa, and at the extreme northern end of the area is the famous black tuna ground around Tanegashima. Throughout the area as a whole the spearfishes are most abundant, followed by yellowfin, bigeye, and black tuna, with albacore extremely scarce. The spearfishes are abundant throughout the year, but particularly from April to August and in general east of 125 E. longitude. The most abundant species is the white marlin, followed by the striped marlin and the black marlin. The seasonal changes in abundance of different species are the same as for the East Fornnosa Sea. The catch of sailfish also appears to increase during the summer. After August the fishing shifts to the vicinity of the 100-fathom line in the East China Sea, and the fishing grounds of this region, although they differ from season to season, extend through the waters west of Kyushu on the north to the Tsushima Strait area. Yellowfin are fairly abundant in April May and November December, and a tendency can be detected for catch rates to increase gradually to the eastward. Bigeye tuna are rather abundant from November to January but appear to be hardly taken at all at other seasons. There are two fishing seasons for black tuna; one is around December and January, with the fishing grounds in the extreme northern part of the region. However, fishing is not very good at this time and the catches are made at some distance from the center of the main fishing grounds. The other season is around April to June, with the grounds on the east side of the archipelago. The fishing is sporadic and there are no concentrated catches. Some albacore are taken from January to March, but they are not very abundant. Table 44 shows the fishing situation in this sea area on the basis of past surveys. The overall catch rate is slightly less than 20, much lower than those of the various sea areas described earlier. Comparing those parts of the area north and south of 25 N. latitude, as the table shows, the catch rates are higher in the north for all fish except the yellowfin, and the overall average catch rate is higher in the north. It will be noted that the catch rates for black tuna and albacore are much greater in the northern part. 81