of if^' is given here for fish of the year because, althoufjh eecond-year and third- 

 year fish are both taken froni May to December, fish of the year are taken only 

 after August); l^r S^Po^ (l~gl+»£_.) . 1,300. Accordingly |JX- p^' - 1*|^ x 



The young yellowfin in the waters adjacent to Sumazu come up throu^ the Ogasa- 



waras together vdth the mature fish and are carried from the south by the same 



ocean currents which bring the inigrt:.tory schools, and for these reasons it is 



probably approximately coiTect to consider that r^s r. Since the catch in Numazu 



waters is made with fixed nets, it is probably also safe to assume that f^ i f '. 



Consequently if £-2 a 1 then p^j .75o The natural aortality rates for both 



young and adult yellowfin do not differ greatly and are thought to be of the 



same order as those for the black ttina. Therefoi'e if Ss .20, the rate of catch 



for the young fish Is f^s 1 - -s^S, - ,062 and that for adult fish is 



•30 



i" = 1 - *S = .287, 



On the Stock of the Albacore, Germo germo (Lacepbde) 

 S^jrnopsis jin English^ 



Stock of Germo gertno (Lacepede) was studied on the basis of catch records 

 classified according to the body-length and body-weight. Survival rate was es- 

 timated to be about ,66, while fishing rate as about ,18. Qend of English 

 synopais] 



The California albacore, which had been showing a tendency to decrease in 

 abundance since 1916, had by 1926 fallen into e condition in which it might be 

 said that there was almoet no catch at all, and that condition has persisted 

 to the present day. (1) In the past the albacore catch on the coasts of Japan has 

 been very small, but under the stimulus of the demand from California positive 

 efforts have been made to increase the catch and the fishing grounds have been 

 extended farther and farther out to sea in the search for the schools. Along 

 with these developments, hoTrever, certain ill omens have appeared in the fish- 

 ing situation. The comparatively large albacore which migrate in close to the 

 coasts in the sumirer have gradually diminished in numbers and the fisheiy has 

 barely been able to keep going by increasing the catch of the medium-sized al- 

 bacore which migrate into the offshore waters in the winter. v2) This may per- 

 haps be due to a change in the course of migration of the albacore, «rtiich are 

 the most truly pelagic of all the tunas, but in case this decline may possibly 

 be due to overfishing, it is a problem which requires a great deal of attention. 

 The present study was undertaken because of my desire to gain some knowledge 

 concerning these points. 



10 



