SUMMARY 



1. During January, February, and "arch, the John P. -occupied 



fishing stations on 155°, 169°, and 180° W. longitude. Fishing 



on 120° and 130° '.V. longitude was done with the Charles H. Gilbert 

 during L!ay and June. 



2. The catches made during these cruises gave farther proof of the 

 presence of a "rich zone" of yellowfin tuna previously reported 

 for the equatorial region. 



3. The latitudinal variation of this zone generally coincided with 

 differences in the prevailing winds. '.There southeasterly winds 

 prevailed, the concentration of tuna was to the north of the 

 Equator, and where the winds were northeasterly or variable the 

 zone was displaced to the south. 



U. The high catches of albacore tuna made in southern latitudes on 

 169° and 180° W. longitude point to a possible area of commercial 

 exploitation .^or this species. 



5. Both the yellowfin and bigeye tuna increase in average size from 

 west to east. 



6. With the exception of the albacore, the tunas (yellowfin, bigeye, 

 and skipjack) showed a greater catch of males than females. 



7. Results of Japanese commercial fishing in the central Pacific 

 agreed closely as to catching rate and sizes of tuna taken with 

 those obtained by POFI vessels fishing in the same general area 

 3 months earlier. 



8. Both yellovjfin and bigeye tuna were usually caught in greater 

 numbers on the deeper hooks. Exceptions probably were due to 

 streaming of the line when the thermocline was at shoal levels. 



albacore catches revealed a mors definite stratification, 

 with deep hooks consistently showing the highest catch rate. 



?. Experimental fishing with longer float lines indicated that the 



modified z°' sr :Yas fishing at a deeper level, and was more efficient 

 in the capture of albacore. 



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