156 EIGHTH PACIFIC SCIENCE CONGRESS 



records of the Japanese fishery indicate that it is annually producing 

 about 30 million pounds of yellowfin tuna and a similar quantity of 

 bigeye tuna, with the catch increasing year by year. 



Fishing of surface schooling yellowfin tuna is not extensive in the 

 western Pacific. During the 1930's the Japanese developed a moderately 

 large fishery for surface-schooling skipjack in the Caroline, Marshall, 

 and Marianas Islands, employing the live-bait technique. Small quanti- 

 ties of yellowfin were taken incidentally. This fishery depended, of 

 course, on supplies of live bait which are not extensive in the Mandated 

 Islands (now the Pacific Trust Territories), and which have not been 

 available to Japanese fishermen since the war. Except for local sub- 

 sistence fishing by islanders of the Trust Territories, and some fishing, 

 mostly by means of traps, in the Philippines, the tuna fishery of the 

 western tropical Pacific is almost exclusively a long-line fishery at the 

 present time. 



There is also a small fishery for yellowfin tuna and bigeye tuna in 

 the immediate vicinity of the Hawaiian Islands. During the summer 

 months, skipjack tuna are taken by live-bait techniques from surface 

 schools, and a few yellowfin are taken incidentally. The main catch 

 of yellowfin, however, is made by long-lines, which capture large sub- 

 surface tunas, averaging over 100 pounds each. The catch is almost 

 entirely marketed for local consumption as fresh fish, and, hence, the 

 volume is limited by the local market. The catch is about two million 

 pounds a year, two-thirds of it being yellowfin and one-third bigeye. 



Research by the Pacific Oceanic Fishery Investigations of the U. S. 

 Fish and Wildlife Service, during the past three years, has demonstrated 

 that large concentrations of sub-surface yellowfin and bigeye tunas are 

 to be found in equatorial waters of the Central and Eastern Pacific, 

 east of the present Japanese fishery. Greatest concentrations occur 

 between the equator and the southern boundary of the counter-equa- 

 torial current, being associated with a zone of current convergence in 

 those latitudes. Sizable surface schools have also been observed in the 

 vicinity of the Line Islands and Phoenix Islands. It has also been dem- 

 onstrated by various commercial explorations that surface-schooling yel- 

 lowfin occur in some numbers in the Marquesas, Societies, and Tuamo- 

 tus. These stocks of yellowfin are at present not fished commercially. 



It would appear that the yellowfin tuna production from the Pacific 

 Ocean will continue to increase, both by expansion to presently unfished 

 areas and by further increase in production from some regions now 

 being fished. 

 Bigeye 



The bigeye tuna, Parathunnus sibi, is fished in the same regions 

 as the yellowfin tuna, and by the same gear. It constitutes an important 



