similar phenomenon in the spearfishes of the waters adjacent to 

 Fonnosao The results j, interestingly enough,, are completely- 

 opposite to the case of the scombroids £, as will be shown later,, 



As regards similar problems with the yellowfin tuna, the 

 'author has only a little material and so cannot set forth any 

 concrete opinion, but table 1 cites an examplon In those fish 

 which are of sizes to the left of the dividing line in the 

 tables the sex ratio is close to 1 s 1,, while in the larger ones 

 there is a marked predominance of maleso This condition cor- 

 responds to that cited by Dro Kishinouye for the early part of 

 the fishingo 



Table lo Sex ratios and size differences by sex 



(yellowfin, June-September 1937 j, Bast Philippine Sea) 



Weight 4 7 10 13 



/ / / / 



16 19 22 25 28 31 34 



^ ^ . , , /////// 



(kg) 7 10 13 16 19 22 25 28 31 34 37 



Females 008643246 



Males 



1 



8 



4 



8 



12 16 

 (61) 



10 18 

 (63) 



37 40 43 46 49 52 55 Total 



/ / / / / / / 

 40 43 46 49 52 55 up 



22 14 12 



30 35 42 26 17 12 



119 

 (58) 



2 227 

 (164) 



Notes Figures in parentheses are the totals on each side of the vertical ruleo 



The distribution of No_ rarus is not yet well understood^ 

 but in Japanese waters it is known only from southern Kyushu to 

 the Nansei Shoto regiono Of all the species of tuna, this one 

 seems to have the greatest preference for the coastal water 

 areas s and it apparently is seen commonly in the vicinity of 

 tropical islandSo 



Figure 6 shows the distribution with respect to latitude 

 of all of the tunas except the black tuna and IL, rarus o The 

 curves of the catch rates in the range of 140° - 150° east 

 longitude have been drawn In the same way as in the preceding 

 f igui'eSo 



As is clear from the figure j, the yellowfin plays a 

 controlling role in the total catch up to the vicinity of 10° No 

 From about 10° - 24° No the spearfishas determine the overall 

 catch rates, and farther north the albacore has the greatest 

 significance„ The big-eyed tuna are somewhat more numerous to 

 the south, but there is no great difference and they are thought 

 to be distributed uniformlyo 



23 



