RECENT STUDIES ON TUNAS AND MARLINS IN JAPAN 



By HiROSHi Nakamura ^ and Yoshio Hiyama 2 



Because the tunas and marlins fisheries are important in this coun- 

 try, numerous works have been produced by our biologists over a long 

 period of time, but here we shall describe some recent achievement of 

 our biologists as regards these fishes. 



(1) Taxonomy 

 Only a few amendments and additions have been made since Kishi- 

 nouye (1923) reviewed the fishes of Thunnidae. Jordan and Evermann 

 (1926) established gen. Kishinoella for Neothunnus rarus Kishinouye 

 and added Neothunnus itosibi. Nakamura (1939) thought the latter 

 had no difference from A'', macropterus, and Serventy (1941) thought 

 the former was a synonym of K. tonggol. Kamohara (1940) changed the 

 name of the Japanese bluefin tuna to Thunnus thunnus Linn, and that 

 of the albacore to G. alalunga. 



About Xiphiiformes, since Nakamura (1937) reviewed Istiophoridae 

 and Xiphiidae of the West part of the Pacific, Hirasaka and Nakamura 

 (1947) made a few amendments and additions. They established gen. 

 Kajikia for Makaira mitsukurii Jordan &: Snyder, added K. formosana 

 and established gen. Marlina for Makaira marlina Jordan & Hill, and 

 added Eumakaira nigra N.g. n.sp. 



(2) Distribution and Migration 



As most of the fishes are caught by the long line in this country, 

 the method of tagging is quite difficult though so many efforts have 

 been made. Now the tagging method for the pole and line fishing is 

 under investigation with the cooperation of both authors. 



Therefore, our knowledge on the migration of these fishes is merely 

 based on the seasonal change of the fishing grounds, about which so 

 many data have piled up already. On the other hand, since Kishinouye 

 (1923), so many biologists like Kimura (1941-1949), Uda (1935-52), and 

 Aikawa (1933) have discussed the oceanographic conditions of the hab- 

 itation of these stenothermal fish species from various points of view. 

 Recently Nakamura worked out the distribution of these fish kinds by 



^ Nankai Regional Fisheries Research Laboratory, Kochi, Japan. 



^ Fisheries Institute, Faculty of Agriculture, Tokyo University, .Japan. 



X65 



