made in Pearl Harbor, through the cooperation of the U.S. 

 Navy and the State of Hawaii. 



Success was achieved in the search for other small fishes 

 that could supplement or replace the nehu. A small clupeid, 

 the threadfin shad (Doivnoma petoioisc) , adaptable to life 

 in fresh or salt water, was introduced into Hawaii in the 

 1950's and has established itself in fresh water reservoirs 

 (figs. 10 and 11). 



In the summer of 1968, under the direction of biologist 

 Robert T. B. Iversen, the Charles H. Gilbert tested at sea 

 the relative effectiveness of nehu and threadfin shad as 

 bait for skipjack tuna. This carefully designed experiment 

 showed conclusively that there is no important difference 

 between catches made with threadfin shad and nehu — one 

 takes just as many skipjack tuna as the other. This result 

 is important, for two reasons: the first deals with tradition 

 and prejudice — earlier attempts to locate an alternate bait 

 in Hawaii concentrated on the cichlid, tilapia. The fisher- 

 men soon concluded that the tilapia simply was not a good 

 bait for skipjack tuna. The result has been that only 

 exhaustive tests, such as have been made, can now convince 

 them that any other bait will serve to catch fish from 

 the types of schools found in the central Pacific. The 

 second reason the result is important is that the threadfin 

 shad, although delicate, is not as fragile as the nehu; it 

 survive.s in far higher numbers in the baitwells than does 

 nehu. A higher survival rate means that a skipjack tuna 

 vessel need not bait so often and consequently that fishing 

 trips can be longer. It appears that even in seasons as 

 mediocre as the past two have been, the catch depends 

 largely upon how much time the vessels spend at sea scout- 

 ing for and catching fish. Threadfin shad is still not the 

 "perfect" bait, if such exists. The Hawaiian supply, which 

 is restricted to a few fresh water reservoirs, may be small 

 in relation to the demands that might be placed on it. 

 Furthermore no one has cultured the animal. Therefore 



the search for other bait species will continue. The de- 

 sired species must meet several criteria : it must be small, 

 silvery, active, and capable of being raised in large numbers 

 at a relatively low cost. Several possibilities are being 

 considered. 



Other Problems of the Fleet 



Although a large resource is known to exist nearby, 

 today the Hawaiian skipjack tuna fleet is a prisoner of its 

 own inadequacies. The vessels are too small to venture far 

 from the islands. Figure 12 .shows the most productive 

 areas fished by the fleet in the period 1948-65. None ex- 

 tends very far from shore. The heaviest catches are made 

 within a few miles of bustling metropolitan Honolulu. The 

 catch is highly seasonal; about 53 percent of it is taken in 

 the summer, with a peak in July. These conditions persist in 

 spite of the presence of a cannery in Honolulu that now has 

 to import tuna to keep operating. Thus a ready market 

 exists. 



In an effort to diagnose some of the more pressing ail- 

 ments of the industry, the Laboratory in the summer of 

 1967 posted seven observers on vessels of the skii)jack tuna 

 fleet. These men studied many aspects of the tuna boat 

 operations. Their data afford the first exhaustive quanti- 

 tative information on how the boats and the fishermen 

 go about their job. This valuable fund of information 

 was collected only through the whole-hearted cooperation 

 of the tuna boat skippers. 



At the height of the .sea.son, the vessels work a 15.5-hour 

 day, leaving port before daybreak and returning after 

 sunset. They see about six schools of tuna, successfully 

 fish about 2.6 of them. The average catch per school is 

 just short of a ton. 



One valuable result of this survey has been the documen- 

 tation of the very wide variability in some aspects of the 

 operations. A boat with a good catch record takes about 



13 



