and Izu chains on the way to the Northeastern Sea Area, 

 where they are also fishedo 



(b) The migratory schools are fished not only 

 in the Ogasawara and Izu areas but also in the seas to the 

 southwest of those islands o Their distribution is broad and 

 unselectiveo 



bo There are thus two groups of schools of different 

 origins coming into the Northeast Sea Area, and con- 

 sequently it would appear that variations in the 

 catch in this area are closely linked with the numbers 

 of fish of these groups which migrate into the areao 

 Andj considering the points (1) that the migratory 

 schools provide 80 percent of the to^al skipjack 

 catch of the Northeastern Sea Area and (2) that medium 

 sized skipjack (h to 8 pounds) make up 70 to 80 percent of 

 both the total number of fish taken and the number 

 of appearances of schools, it is thought that most 

 of the skipjack schools in the area are medium-sized 

 migratory schools and that the numbers in which they 

 migrate into the area have a great effect on the 

 catcho 



Notess (a) Fish under 26 cm body length are first-year 

 fisho Those 26 - 3ii cm are second-year fisho Those 3h - h3 

 are third-year fisho Ihose k3 = $h are fourth year fisho Fish 

 longer than ^k cm are in their fifth year or older o 



(b) Considering the catch in the Northeastern Sea 

 Area from the point of view of the sizes of fish taken, the 

 order of importance is medium, large, and smalls, but in the 

 Zunan and Satsunan Sea Areas the order is small, medium, and 

 large o In general ^ small skipjack are few in the north and 

 numerous in the south » 



(c) In the Northeastern Sea Area the catch for 

 1936 was the greatest in the last ten years in number of fish 

 taken, but the fishing situation was abnormal rrith the main 

 part of the catch consisting of small fish of around 2o5 pounds 

 (under h pounds) o 



/J^ n j-i- * 4. weight (gr) x 1000 



(d) Condition factor ^ , S n^^ ) &-^ i ^ — _ 



length ^cmj ^ 



12 



