season it gradually becomes more dispersed ajid the fishing grounds shift gradually from south to 

 north. However, as there is sporadic fishing of black tuna at almost the same season in tlie 

 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 show- 

 ing 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 actuzilly 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 nniles 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, spear- 

 fishes, and sharks, however, it can by no mejins be thought to be a superior fishing ground. 



The waters of the Okinawan airchipelago 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 aind the Miyako Archipelago and south of the main is- 

 land 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 abundcint, 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 nnade at some distance from the center of the nnain 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 situ- 

 ation in this sea area on the basis of past surveys. 



The overall catch rate is slightly less than 2.0, much lower than those of the various 

 sea areais 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 yellow- 

 fin, 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 



