should probably be interpreted only as meaning that there is a possibility of such catch rates 

 occurring. 



Turning next to the northward to the waters around Tanegashima, the peak fishing 

 season is from December to February, catches continuing to be made into March, with fairly 

 high catch rates being indicated in some years even in April. Farther to the east in the waters 

 extending to 145 E. longitude and including the Ogasawara area, catches are made from April 

 to June, but on the whole they are extremely scattered and the catch rates show very low values. 



Considerable fish are taken in June and July off the Tokiwa region of eastern Honshu. 

 Densely congregated schools again appear fronn the Sanriku region of northeastern Honshu to the 

 south coast of Hokkaido and fish are teiken continuously fronn July to November. 



In the area east of 140 E. longitude and centering between 30 and 35 N. latitude 

 some black tuna are taken, the season being fronn Novennber to March. However, in this region 

 there are practically no exploratory data for any season other than November to March, nor are 

 there any vessels actually operating there except at this season, therefore, the occurrence of 

 tuna at other seasons is connpletely unknown. 



At almost the same tinne (November to March) that these sporadic catches have been 

 nnade in the broad expanse to the east of 140 E. longitude, rather dense schools appear in 

 waters around Taunegashinna. The question of what route these schools follow before appearing in 

 this area is not as yet concretely answered. However, judging fronn the changes in fishing con- 

 ditions in this area and in other areas, it is thought that these are not already organized schools 

 which have nnigrated in fronn other regions, but that the fish gradually congregate and form 

 schools in this area. Up to the end of March these schools nnove extrennely slowly with each 

 succeeding day toward the northeast, but after the end of March, when they reach the waters of 

 Miyazaki Prefecture, they suddenly disappear and the densely populated fishing grounds vanish. 

 Hitherto the established theory has been that the schools follow the Japanese coast to the North- 

 eastern Sea Area, but annong the fishermen in the Aburatsu area there are some who clainn that 

 the direction of the migration shifts to the south from the vicinity of Toi Misaki (on the west 

 coast of Kyushu). 



Around the end of the fishing season off southern Kyushu, dense schools of black tuna 

 appear in the northeastern portion of the South China Sea and fishing flourishes for an extremely 

 short period on the east and west coasts of the island of Luzon. The peak of this fishery is in 

 April aund May, the fishing falling off rapidly in June. Judging fronn the changes in this fishery, 

 it may be thought that the schools fronn this area gradually nnove along the Okinawa chain, but 

 there is as yet no concrete proof that this is or is not the case. 



At about the sanne period sonne black tuna are taken in the northern portion of the 

 Ogasawara Islands area, aund there is sonne catch in the waters off the Tokiwa region of eastern 

 Honshu. It nnight be thought that this represents a nnovement of the schools which were densely 

 congregated off southern Kyushu, but if we consider the broad distribution this would entail, 

 there is doubt as to whether or not the schools fronn the Tanegashinna waters have beconne so 

 widely distributed as to appear all over the whole area directly under the influence of the 

 Kuroshio, from the waters off Luzon to the coasts of Japan proper, at almost the same time. 



We have almost no data with which to investigate the relationship between the schools 

 which appear around Tajiegashinna and those fronn the Luzon airea, but they can be thought to be 

 different schools in view of the following three points. The first point is the difference in the size 

 of the fish. The schools which appeared around Tajiegashinna were nnostly small fish of around 

 165 pounds in the early years of the Showa Era (1925 to 1930). With each succeeding year the 

 fish have become larger and airound 1940 their average weight was about 450 pounds (figure 13). 

 Around Luzon the fish were very large when the fishery was first developed in 1935, with fish 

 of 655 to 820 pounds in the early part of the season, gradually declining in size as the days 



140 



