parable data for shad, since the shad were not 

 placed directly into the baitwells but were 

 placed first into 2,350-liter (620-gal) portable 

 transfer tanks and then into the larger 34,850- 

 liter (9,200-gal) holding tanks for several days 

 prior to being placed into the baitwells. How- 

 ever, it was not unusual to place about 10,000 

 to 15,000 shad in a 2,350-liter oxygenated tank, 

 transport them for 37 km from the reservoir to 

 the larger holding tanks and find less than 50 

 dead shad on arrival. In placing shad aboard 

 several vessels using a variety of transfer 

 methods on other occasions, the average mor- 

 tality the following day was 16% (Iversen and 

 Puffinburger ). Assuming optimum transfer 

 conditions, a mortality rate of 10% by the fol- 

 lowing day appears attainable. During Gilbert 

 cruise 116, 113 buckets of shad were carried in 

 the ship's baitwells and 30 buckets in portable 

 tanks on deck a distance of 4,300 km southeast 

 of Hawaii for use as live bait in skipjack tuna 

 fishing (Hida, 1970). Although mortalities in 

 the portable tanks were about 50% due to bait 

 being lost through open seams in the tank cov- 

 ers, mortalities in the regular baitwells were 

 negligible. 



Use of a live bait with a lower mortality rate 

 than nehu could result in a reduced overall bait 

 requirement, but only if the fishing effort re- 

 mained unchanged. A reduced bait requirement 

 is unlikely to happen because the purpose of 

 developing a substitute bait is to increase fish- 

 ing effort. What is more likely to happen is 

 that use of a hardy bait will allow fishermen to 

 increase the number of trips, fish farther off- 

 shore, or possibly increase the duration of each 

 fishing trip. Presently most trips last 1 day 

 and the boats rarely fish more than 170 km 

 from the islands (Uchida, 1967). The net result 

 could well be an increase in the total amount of 

 bait needed. 



The availability of bait-sized shad must also 

 be considered. Landings of skipjack tuna in 

 Hawaii are highest during the months of June 

 through August, lowest in November through 

 March, and intermediate in the remaining 

 months (Brock and Uchida, 1968). In Hawaii 

 shad begin to spawn in the late winter and early 

 spring, with the heaviest spawning apparently 

 occurring in February and March. In about 10 

 to 12 weeks the young shad grow to 40 to 50 mm 



'iversen, Robert T.B.,and Jay 0. Puffinburger. 

 Capture, transportation, and pumping of threadfin 

 shad, Dorosoma petenense . Unpublished MS. 



and are large enough to use as bait. The avail- 

 ability of bait-sized shad thus coincides with 

 the heaviest demands for bait from the fisher- 

 men during the summer. Bait-sized shad must 

 also be abundant enough to meet needs. In re- 

 cent years, the annual catch of nehu has aver- 

 aged about 24,500 buckets (Uchida, 1967). It is 

 not known how large an impoundment would be 

 required to produce that many buckets of shad. 

 During 16 days of baiting in Wahiawa Reser- 

 voir between February 18 and June 15, 1970, 

 we captured 1,025 buckets of shad, an average 

 of 64 buckets per day. More could have been 

 captured, for the amount removed was limited 

 by the carrying capacity of our portable tanks. 

 Wahiawa Reservoir probably contains at least 

 5,000 buckets of shad in the summer. The 

 reservoir has a surface area of 122 ha (302 

 acres) at high water. Thus it may be possible 

 to culture enough shad in a pond or impound- 

 ment approaching the size of Wahiawa Reser- 

 voir to satisfy a significant percentage of the 

 fleet's total bait requirements, providing the 

 cost of culturing, capturing, and acclimatizing 

 the shad is economically feasible. 



What Remains to be Done? 



On a short-term basis, the next logical step 

 is a comprehensive sea test under actual com- 

 mercial conditions. Providing enough shad to 

 one or more commercial boats so that they 

 could fish exclusively with shad during all or 

 part of the peak fishing months would produce 

 information on fishing effort and catches due to 

 the use of a substitute live bait. More precise 

 information is also needed on the amount of 

 shad that can be cultured in ponds of different 

 sizes and on the costs of shad culture. The 

 results of a comprehensive commercial fishing 

 test and cost estimates for culturing shad 

 should lead to a rational decision on the eco- 

 nomic feasibility of using shad as a substitute 

 live bait for nehu. 



On a long-term basis, biological investiga- 

 tions are needed to determine if the shad's 

 reproductive cycle can be manipulated to pro- 

 duce earlier spawning and if it is possible to 

 raise shad on a large scale in a bait hatchery. 



SUMMARY 



1. In order to compare the effectiveness of 

 threadfin shad with the anchovy (nehu) normally 

 used as live bait for skipjack tuna fishing in 

 Hawaii, 37 schools of skipjack tuna were fished 



