In May and June in the waters off southern Japan, in the Zunan area, 

 and off Nojimasaki as much as 85 ■= S9% of the catch is made up of ZDedium 

 skipjack of 350 =■ 550 inomme which are thought to form the later Group A of 

 the Northeastern area, agreeing pretty well with the weight composition of 

 Northwestern waters, laut in the Satsunan and Ogasawara areas the catch 

 contains a mixture of all year=elas0©s from young fish of about 250 momme 

 to old fish of about 2 kan and over half of the catch is made up of big 

 fish of 550 momme and overo During the period July - Octoberj when the 

 Northeastern area is having its peak season, no particular diminution in 

 the number of medium skipjack is perceptible, and in the winter season large 

 fish of 550 momme and above become markedly numerouSo 



It is, of course J net possible from body-weight data alone to determine 

 the age or provenance of the schools, but it is presumed that in the waters 

 of the Satsunan and Ogasawara islands the schools mainly composed of young 

 fish of 350 momme and under and mature fish of 550 mcjime and over remain 

 as sedentSry fish, while the medium-sized fish of 350-550 m omme . which are 

 regarded as being of roughly the same age-=class (fourth^year fish), come 

 from somewhere to congregate off Shikoku, in the Kumano Nada, and off 

 Zunan around May and June.. These are presumed to be the fish which move 

 north to the Northeastern sea area between July and Octobero It is 

 thought that in order to forecast the skipjack fishing situation in the 

 Northeastern sea area it is important to know not only the situation as 

 regards the sp*,wning and growth of the skipjack which are to form this 

 group of mediTim^ sized fish (fourth-year fish) but also the amount of 

 third-year fish and the conditions which govern the migration of the 

 fourthly ear fish„ 



Finally I wish to express my gratitude to Dro Uda for his guidance 

 and encouragement and to the Kesennuma Land Radio Station for the data which 

 was supplied me, and I hope to take in the future and in other sea areas as 

 many fish measurements as possibleo 



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