Auxis aaru 



Juveniles of this species are obtained from time to time in the 

 same manner as the juvenile skipjaok, which they olosely resemble in their 

 development. These fish oan easily be distinguished from their outward 

 appearance alone by the thinner body and the discontinuity of the dorsals. 

 As examination of the visoera shows that the right lobe of the liver is 

 thiok and long, reaching to the anus, and the walls of the rectum are 

 thick. Their food, like that of the skipjaok, consists of larval oopepods 

 and decapods. 



Date Length Location 



May 75 mm 



May 21 80 mm (2 fish) Gonsone 



June 192 3 145 mm 



July 1923 145 mm 



Yellowf in tuna ? [ Neothunnus macropterus ] 



One juvenile thunnid 100 mm long was collected by Mr. Umemoto from 

 the stomach of a skipjack taken at Gogosone [29°30 , N, 129<*B f E] on May 10, 

 The skin and viscera had been damaged. It is broader than juvenile bonitos, 

 the caudal fin is large, and the first dorsal is high. From the large site 

 of the eye it might perhaps be thought to be a juvenile big-eyed tuna 

 [ Parathunnus mebaohi J, but it is perhaps better to consider it a juvenile 

 of the yellowfin tuna f which are abundant in the vicinity. A small air 

 bladder oan be seen on the dorsal surface of the body oavity. At some 

 time in the future when a large number of specimens of this type oome 

 to hand, it will probably be possible to find out to what s pedes these 

 juveniles belong. No big-eyed tuna or yellowfin with ripe eggs have been 

 seen hitherto, and it is not known when they spawn or at what size they 

 mature, but this juvenile was apparently hatched around March or April. 



The above information all concerns pleoostean fishes. 



Inusawara t [Cybium ohinense ] 



A 26 ran juvenile which Mr. tiaemoto took from the stomach of a 

 skipjack at Gonsone on April 14 was thought to be a plecostean, but from 

 the large size of the mouth and the fact that the maxillary projects 

 slightly past the posterior edge of the eye it is judged to be a cybiid. 

 The head is large, occupying more than one-third of the total length, and 

 both lobes of the caudal fin are broad and somewhat rounded in outline, 

 although they appear small in comparison with the breadth of the body* 

 The identification as an inusawara is based on there being 18 vertebrae 

 anterior to the anus. 



Gurukun [ Rastrelllger chrysozonus ] (reported in 

 ""under the name agifurakiya) 



Vol. 1 



Specimens from 20 to 37 mm in length were recovered from the stomachs 

 of skipjack taken at Gonsone on April 14. The body is slender and the fish 

 closely resemble young mackerel. It appears that they grow to about 150 mm 

 by the latter part of May. This rate of growth is very rapid oompared to 

 that of the European mackerel, which is said to grow on the average 10 mm 

 per month. 



14 



75JJ1 



