to low-temperature areas^ of Isss tiian ^ Co in the iwintar and 

 it is presumed that warm-water fishes such ac .^he skipjc?,ck 

 wo'old find it difficult to sndiire such viclsnt oceanographic 

 changesj which are thought to ba special?>.y ursuitable for hheir 

 spawning and for the growth cf the larval fish| also because 

 actually the fish catch ceases xvj. the winter and no fish are 

 seen (it happens rarely that one is hooked on tuna longlines 

 during tiie winter in vfarra-water masses far off to the east); 

 and because the catch of laxgs and small fish is raarkedly smaller 

 than that of mediusn fisho However _, in the Satsunan and Zunan 

 sea areas tliroughout the whole fislung season some schools of 

 medium-sised skipjack are fished along with the schools of large 

 and small fish that concentrate in the vicinity of islands and 

 reefs and for thiis reason we knew of the existence of other 

 schools v.'hich are comparatively sedentary' and rcake only email 

 migrations in addition to the north-south migrating schools 

 described above o 



The foregoing discussion is based on only the data for one 

 year so there are many points whd.ch require much further studj'' 

 and examination in the future„ Farticolarly the distribution 

 of large, mediuiTi, and snail siaes, various degrees of maturityj 

 and various degrees of fatness and leanness must be investigated 

 in detail J and the actual paths of the migratory movements of 

 the schools must be ascertained by tagging as many skipjack as 

 possibles 



Skipjack schools and the objects with ^vhich they ^r^ 

 asso ciatedn ~A study'like th? one previcusly rsportedS/ Yvag 

 carried out in 1933 throughout the whole fishing season and 

 over the ifldiole fishing area. Table U shows the number of 

 appearances of each type of school and the n-oinber of fish 

 caught in each month » In the Hokkai-Sanriku sea area the 

 greatest number of appearan.ces is that for unaccompanied schools 

 followed by schools associated mth sharks, birds _, whales, and 

 logs in that order o For the total number of fish taken the 

 order was shark-associated, iznassociated, vmale-associatsd, 

 bird-associated, and driftwood-associatedo Conbiiiing the tiTO 

 categories we find that shark-associated and unassociatsd schools 

 are far more numerous than the ether types „ In contrast to this 5 

 in the Zunan Sea Area there are chiefly bird-»a.3sociated and 

 sedentary schools, followed by unassociated sciiools, the extremely 

 small number remaining being driffeYood-associated azid shark- 

 associated in that order. In the Satsun^Rn Sea Area bird-associat&d 

 schools are by far the most numerous followed by sedentary and 



-/ Michitaka Udas Sea conditions in the raters adjacent to Japan 

 in each month averaged over a nun^ber of years. Fisheries 

 Experiment Station Reports Nos„ 1, 2, 3o 



5/ 



Iklichitaka Udas Tne shoals of "katuwo" and their angling. 

 Bullo Jap„ Soco Sci, Fish, 2 (3)s 1933o (Sea p„ 68)0 



5> 



