twice as much fish per trip as one with a poor record. It 

 fishes just about as many schools, but the yield per school is 

 higher. 



The object of this study is to design new and better 

 fishing strategies and tactics for the Hawaiian fleet. This 

 can be done only after careful analysis of the data. All the 

 1967 data have been transferred to cards and run through 

 specially devised computer programs. The observational 

 program was repeated in 1968. The resulting data are now 

 being prepared for analysis. 



The catch in 1967 was very poor; 1968 was somewhat 

 better, but not much so. Badly needed now ai'e data from 

 a good season, so that operations under varying conditions 

 of yield can be compared. 



Preliminary results already provide numerical data where 

 only estimates had been available before, such as the 

 amount of bait taken and how it is used. The seven vessels 

 studied used about 25,000 pounds of nehu as bait during 

 June, July, and August 1967, according to Laboratory 

 scientist Richard N. Uchida. Most of the nehu were used 

 in chumming schools from which fish were caught. About 

 four buckets (appro.ximately 32 pounds) were used, on the 

 average, for each successfully fished school. The skippers 

 spent little i)ait on schools that could not be fished. 



The material shows that in the summer of 1967, which 

 was a poor skipjack tuna season, catches of fewer than 200 

 fish each were made in about three-fourths of the schools 

 successfully fished. 



FIGURE 11, Plocid Wahiowo Reservoir, a few miles outside of Hono- 

 lulu, holds the lorgest supply of thrcodfin shod in Hawaii. The fish 

 were seined there ond transported by truck to Honolulu for tests 

 at seo. 



The skipjack tuna appear in schools in which generally 

 all of the fi.sh are about the same size. That is, there are 

 schools of small fish and schools of large fish, but no 

 schools of small and large fish mixed. The boats that 

 fished the schools of small fish got smaller total catches 

 than those that fished large fish. Schools of large fish 

 provided catches as large as 10 tons, as against an average 

 of 1 ton for all the catches. 



The study shows that the Hawaiian skipjack tuna fleet 

 attempts to fish about 80 percent of the schools sighted, 

 but that only half of the schools sighted yield successful 

 catches. A surprisingly large percentage of the fish are 

 now escaping the fishermen's efforts to catch them, Uchida 

 says. 



The Larger Resource 



Kiitsinroinis pclamis. the small tuna that is called skip- 

 jack tuna ill English, aku in Hawaiian, is caught around 

 the Hawaiian Islands throughout the year. Total catches 

 have varied from 6 million to 16 million pounds a year, 

 but be the year good or poor, the best catches have always 

 been made in the summer. It has thus seemed probable 

 to fishery scientists that in addition to a local population 

 of skipjack tuna, the Hawaiian fishery is drawing upon a 

 migrant population that visits the islands in greatest num- 

 l)ers in summer. Within the past few years, scientists at 

 the Laboratory in Honolulu have concluded that these 

 "season" fi.sh, as the summer migrants are called, are 

 part of a large population resident in the central Pacific 

 Ocean. They hypothesize that one of the main spawning 

 grounds of the skipjack tuna lies to the .south and east of 

 Hawaii in the equatorial central Pacific. Fish spawned 

 there migrate to the west coast of Central America and 

 Mexico, where about 70,000 tons of young fish are har- 

 vested annually. Within a few months, the hypothesis 

 holds, the skipjack tuna then turn westward again, return- 



15 



