NATURAL HEEOUECES SECTION 



HEPOHT NUMBSH 104 



9 March 1948. 



THE JAPANESS TUHA FISHEHIES 



SUMMARY 



1. Japan la admirably situated for exploiting the tunas, as many tuna ■pecieii enter 

 Ite waters at some time during; their wide migrations. It has thus heen possible for the 

 Japanese to catch these species and to recognize them as desirable food items since ancient 

 times. 



2. Prior to and during most of the Melji Era (1867-1912), tuna fishing operations were 

 on a small scale and confined to coastal waters. With the introduction of irotor-driven ves- 

 sels, however, taking increased amounts of tuna became possible, especially from the off- 

 shore pelagic waters. The fisheries were therefore able to expand until they now rank as 



a major Japanese Industry. 



3. During the 1930' s the tuna catch in coastal and offshore home waters approached 

 its maximum, and it becaune evident that increased production would require the exploitation 

 of overseas fishing grounds. Moreover, the opening of foreign markets for tuna products 



in 1929 created eiddltional enthusiasm for developing the fisheries further. In the years 

 prior to World War II explorations were undertaken to determine new areas that could con- 

 tribute materially towards an increased tuna catch. Albacore fishing grounds were located 

 in the mid-Pacific area and were fished Intensively. Major fishing grounds for the yellow- 

 fin tuna were discovered in the tropical zone. Cominerclal fishing operations In the former 

 Mandated Islands began in 1938, but the catch never reached large proportions because fuel 

 allotments to fishing vessels operating from home ports were considerably curtailed by the 

 army euid navy. Thus, in the years before World War II, Japanese tuna operations were con- 

 fined largely to home waters, although much Information was obtained which indicated the 

 possibility of further expansion in the fisheries. 



4. Knowledge of the extent of the tuna groande in the western Pacific Ocenn is most 

 complete for the commercially important species. The research on this group of fishes also 

 reflects their importance to the Japanese. The skipjack, black tuna, albacore, and yellow- 

 fin tuna are the only tunas for which biological information of any consequence has been 

 obtained. However, much of this information is unco-ordlnated and scattered throu^ the 

 literature. 



5. The main types of fishing gear used in the tuna fisheries are the pole and line amd 

 the long line. Pole and line angling, employing live bait or a jig as a lure, is practiced 

 for surface fishing. The species most comironly obtained by this method is the skipjack. 

 Albacore, yellowfin tuna, or big-eyed tuna of small size, found feeding on the surface, are 

 also taken with this gear. The long line technique has been developed to a high degree of 

 perfection by the Japanese in order to fish b'elow surface levels la the offshore pelagic 

 waters, Albacore, black tuna, yellowfin tuna, and big-eyed tuna are teJcen largely by this 

 method. Marlins, swordflsh, and eallflsh are also caught in considerable numbers on long 

 lines and are included by the Japanese in the species comprising the tuna fisheries. Other 

 tuna gear of lesser importance are the huge trap-like set nets, drift nets, circling nets, 

 trolling Jigs, and spears. 



This report was prepared by Dr Sidney Shapiro, scientific consultant. Fisheries Division. 

 Dr Katsuzo Kuronuma, biologist at the Tokyo Central Tlsheries Experimental Station, aided 

 materially in compiling the data. All Illustrations were made by Kateuyuki Klta and Saburo 

 Satouchi, draftsman and artist respectively for Fisheries Division. 5 



P-6307 



