SUMTMRY 



lo There were three longline cruises during 1950 and 1951o These 

 were designed to ascertain the distribution and abundance of 

 deep- swimming tunas in the central equatorial Pacific Oceano 



2o The longline catch was composed of large tunas, eogoj, 80= to 150- 

 pound yellowfin tunao Surface catches in the same general area 

 were composed of smaller individuals. This is apparently the 

 result of an ecological preference rather than gear selectiono 



3o At the longitudes surveyed (150°-160° W„ longitude) there was 

 a concentration of deep-=swimming yellowfin tuna between 1 =• 

 6* II„ latitudoc This concentration appears to have been due 

 to an increased food supply resulting from equatorial upwelling 

 of rich water o 



4„ Tne oceanic concentration of deep^swimming tunas did not appear 

 related to the islands of the central PacifiCo 



5, Frequentlys catches in the immediate vicinity of small islands 

 'were better than their oceanic counterparts, indicating that 

 these islands exert an influence favorable to tuna within a 

 few miles of their shoreso 



6„ The deepest=fishii:g hooks of the longline gear frequently caught 

 more tuna than hooks fished at a shallower level o 



7, Generally males greatly outnumbered females in longline catches 

 of tunas o 



8„ The equatorial stocks of deep=swimming tunas appear to represent 

 a resource capable of supporting an American fisheryo 



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