C. Sharks 



There are a great many species of sharks, but among them the following 10 or so 

 species have an especially close connection with the tuna longline fishery. 



Differences can be detected in the habits of these various species. Some of them 

 have a distribution and a migrational habit resembling that of the yellowfin, while others move 

 in a way resembling some of the spearfisnes. In some cases their migrations precede and in 

 others they follow those of the tunas and spearfishes. As almost nothing is known as yet of these 

 relationships, it is far from the stage of practical application, but if thorough studies are made, 

 it may be thought that there is ample possibility of using these sharks as indicators of fishing 

 grounds and fishing seasons. Hitherto, there have been no studies at all from this point of view, 

 howfever, but in the future this sort of work should be emphasized. 



1. Aozame, Isurus glaucus (Miiller and Henle) 



Also called aoyagi , iragi, and shibibuka. 



The body is spindle-shaped, and the snout is pointed and equipped with sharp teeth. 

 It reaches a length of about 4 meters. The back is a deep indigo blue and the belly is white. 

 This fish occurs widely in warm seas south of central Japan, but is not abundant. The skin is 

 said to be the best for leather of any shark skin. 



2. Rakudazctme , Isurus nasus (Bonnaterre) 



Also called moka and nezumizame . This fish is stouter than the aozame. Whereas 

 the aozame is a warm-water species, this species prefers cold waters and is numerous from 

 northeastern Japan northward. In northeastern Honshu a longline fishery has developed which 

 has this shsirk as its special object. This is the so-called mokanawa . 



3. Hachiware, Alopias profundus (Nakamura) 



Foxshark or thresher shark (Engljind). 



This is one of the thresher shark family and its caudal fin is broad and equal in 

 length to the rest of the body. The eyes are large and of the shape of a gourd turned upside 

 down. This shark attains a length of more than 4 meters and inhabits warm seas. 



4. Onagazeime , Alopias pelagicus (Nakamura) 



Foxshark (England). 



This shark resembles the preceding species, but its caudal fin is longer than the 

 rest of the body eind narrow. The eyes are small and of a green-gray color whereas in the 

 preceding species the eyes are of a blackish-gray color. This species is widely and generally 

 distributed in warm seas. Both species attain a length of about 4 meters. It appears that there 

 is yet another very similar species but little is known of it at present. 



5. Itachizame, Galeocerdo ctrcticus (Faber) 



There are brown markings on the body. Large specimens attain a length of 3 meters. 

 This is a very widely distributed shark, ranging from the Equator to the vicinity of 80 N. and S. 

 latitude. It is generally most abundant in the vicinity of islands and often eats gulls and other 

 water birds, for which reason it is called the "bird shark" in Formosan Chinese. It is an extra- 

 ordinarily voracious animal, and humjin bones and so forth are found from time to time in its 

 stomach. 



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