Homogeneity of the Groups of Black Tuna m the Sat&unan Sea Area 



[Inglish title and synopsis] 



/ippearances^of t 

 South of Kyushu 



Appearances^of^the Groups of XhnnnuP. oriental is (T„ & S„) in the -ieas 



SYNOPSIS 



Average catch per boat per voyage as well as the average body-weight 

 of Jhunnus orientalis (To 6c S„) fished during every decade of the months 

 in the seas south of Kyushu was investigated with the daily records of 

 the landings from long-line fishijig-boats for tunny at the two ports 

 Aburatu. and WangS from Decn 1934 to Jvine 1939, as basis o 



Generally speaking, larger fishes appearing early in the fishing 

 season gradually give place to the sraalier-sizedo iiinor fluctuations 

 in the average body-weight, however, can be recognized as follows s — 



Seasons From mid-Dec o Early and mid- iiid to late Late Aprilj Towards 

 to early Jan,, Fobo, inarch, mid-June 



Aver .weight: cao55 Kwan cao 45 " ca» 52 " oa u 40 " cao47 " 

 (206 kg), (169 kg), (195 kg), (150 kg) (176 kg) 



Hauls: At the beginning vYith earlier With later Towards, At the end 

 of hauls, good hauls, good hauls, and of hauls o 



^nd of English synopsi¥| 



_(1) 

 Hiroaki Aikawa and ^^asuo Kato have used the vertebrae of the 



honmaguro, Thunn us orientalis (Xemminck & Schlegel) to determine its 

 age, have found tne ranges of length and weight, the growth rate, and 

 the condition factor for each age, and from the records of the landings 

 at Aburatsu m 193 7 they J-ave shown that the tuna landed at Aburatsu 

 consist mainly of three groups of eighth-year, ninth-year, and tent-h-year 

 fish. Of these eighth-year fish form 31?S, ninth- year fish 49?^, and 

 tenth-year fish 20^ of the whole catch o The percentage of eighth-year 

 fish does not change markedly throughout the whole fishing season^ but 

 the ninth-year fish are most numerous in the peak season, and the tenth- 

 year fish a re rather numerous only at the beginning of the season » 



The present authors have made a study of the general trends and 

 changes throughout the fishing season in the tuna schools whiii migrate 

 into the Satsunan sea area, basing the work on the records of the number 

 of vessels returning from fishing, the number of fish landed, and the 

 weight (in kan [^o27 poundFJ ) of fish land«d as given in the daily reports 

 of the tuna long-line fishing situation (a very few troll-caught fish 

 are included) at the two ports of Aburatsu and Nango (Sakaematsu) from 

 December, 19o4, to Jun.e, 1939 o 



(•l-i Aikawa, Hiroaki and i^^asuo Kato;; Bullo Japo Soc„ Scio Fish, 7(2), 1938. 



17 



