Schools of fish are present in these waters, where the^- are known as 

 " sukiipju jyakku . " 



Thus the skipjack is distributed throughout a wide area of the 

 Pacific centering on the Equator, and although there ars seasonal dif- 

 ferences in density, they occur in these waters at all times. Beginning 

 in the latter part of February, detached schools pass the Nansei Shoto 

 and appear in the Satsunan area, while other schools appear from the 

 fferianas to the Ogasawara and Zunan areaSo In mid-summer, they migrate 

 into the Sanribj area, but in the autumn, they turn southward and disappear, 

 leaving no skipjack population in those waters^ TtiO fact that the dis- 

 tribution of skipjack in Japanese waters is, for the most partj related 

 to this one pattern of migration, has been the reason for the development 

 of the peculiarly Japanese method of fishing and has set the stage for 

 the skipjack fishery » 



Section 2 Outline of Migrations 



The general terra "skipjack" (_ katsuo / includes four species, the 

 tine skipjack / magatsuo /, the sumagatsuo / Euthynnus XSit£=yj "^^^ 

 hagatsuo / Sarda orient alis /^ / A-gxis t hazard ~77 These are all tropical 

 fish which always live in sea areas which have high water temperatures. 

 They migrate into Japanese waters witn the Kuroshio in the summer. 



(1) Sumagat suo (yaito) (watanabe) / Euthynnus yaito / 



This skipjack is without longitudinal black stripes on the sides and 

 has several black spots below the pectoral fin. It characteristically 

 likes to live in the swift currents off promontories „ A coast-dwelling 

 fish, it prefers to stay close to islets, reefs, banks, and shoalSo While 

 it does inhabit swift currents, it avoids the heart of the current and 

 swims in ■che compai*atively slack water„ The fish characteristically chooses 

 a place for its nest and stays there, spotting with its keen eyes the 

 crustaceans, squid., and small fish which come drifting by and catching them 

 for food. It v;i" '. sometimes pursue its prey up toward the sur-face, but 

 usually returns -go its nest without going very far. In the dim light of 

 morning and evening these fish leave their nests and forming small schools 

 leap about en the surface. They rarely migrate out into the open sea and 

 even when moving from island to island they usually do not rise to the 

 surface layers. For these reasons they are unsuitable as the object of a 

 skipjack fishery, and they seldom migrate north of Choshi„ 



(2) Ha j;atsuo (sujigatsuo) ( kit sune gat suo ) ( hosan ) / Sarda orientalis / 



This is a fish of the offshore waters and generally swims close to 

 land at moderate depths.. They migrate into Japanese waters in small schools. 

 On their way north they are taken in set nets at places where the current 

 passes close to shore or at promontories, or when they chase young anchovies 

 into the bays. They ordinarily live close to land and rarely go out into 

 the open sea. They take dead biit as well as live bait. They also migrate 

 north in the Japan Sea, The dorsal portion of the body has many fine 

 longitudinal stripes, and the teeth are long and sharp. 



16 



