Analysis of the Operations of 

 Seven Hawaiian Skipjack Tuna Fishing Vessels, 

 June-August 1967 



By 



RICHARD N. UCHIDA, Fishery Biologist 

 and 



RAY F. SUMIDA, Biological Technician 



National Marine Fisheries Service 

 Hawaii Area Fishery Research Center 

 Honolulu, Hawaii 96812 



ABSTRACT 



Analysis of operational data collected from seven Hawaiian skipjack tuna 

 fishing vessels in the summer of 1967 showed that the vessels expended 38 per- 

 cent of their day-baiting effort at Kaneohe Bay, which yielded 14.7 buckets of 

 bait per set. Keehi Lagoon was, by far, the most productive night-baiting 

 ground; it received 84 percent of the night effort and yielded 10.4 buckets per 

 set. 



On fishing trips which averaged 15.5 hours, 31 percent of the time was 

 devoted to traveling to and from the fishing grounds, 62 percent was occupied 

 by scouting, and only 7 percent was actually spent fishing. The vessels chummed 

 83 percent of the schools sighted, successfully fished 57 percent of the schools 

 chummed, and used an average of 12.8 buckets of bait per trip. Most often seven 

 men fished per school. Fishing duration among the vessels ranged from 1 to 

 155 minutes, but most schools were fished only for short periods. 



Schools of large skipjack tuna (7 kg. or more), which dominate the summer 

 catch, were usually fished further offshore. 



About half of the schools sighted were in waters to the west of Oahu. 

 Sightings increased from daybreak to a peak at 0801-0900, dipped at 1001-1100, 

 then rose to a second peak at 1301-1400. The vessels caught 62 percent of their 

 day's catch after 1200. Cloud cover and wave height at the time of fishing had 

 no effect on the success or failure in fishing the school. Although the predom- 

 inant species of bird associated with the school was not a good indicator of fish- 

 ing success, size of the bird flock differed significantly among those schools 

 with and without catches. Among schools yielding catches, the vessels found 

 most associated with 50 or more birds; among those unsuccessfully fished, the 

 vessels found most associated with 11-50 birds. 



Data on support activities showed that it usually took nine men one-half hour 

 to unload about 3.4 metric tons of skipjack tuna. The rate of unloading depended 

 largely on the size of the fish. Loading ice required 6.6 minutes. 



Comparison of data from high- and low-producing vessels showed that a 

 high-producing vessel chummed the schools longer, used more bait in fishing, 

 tended to remain with the school longer, and was successful in fishing a higher 

 percentage of the schools it sighted. 



