Figure 1. — Threadfin shad, 

 Dorosoma petenense . 



Figure 2. — Nehu, 

 Stolephorus purpureus . 



actual fishing time and should increase the 

 overall catch of the fishermen. 



Threadfin shad were first introduced into 

 freshwater impoundments and streams in 

 Hawaii in 1958 and by 1960 had become es- 

 tablished in several reservoirs (Hida and 

 Thomson, 1962). Among the attributes of 

 threadfin shad which led to their investigation 

 as a new baitfish are: tolerance to both salt 

 and fresh water, hardiness, silvery color, size, 

 swimming behavior, and low mortality during 

 mass handling. Also, the use of threadfin shad 

 would not require any major changes in the 

 methods used by skipjack tuna fishermen in 

 Hawaii. In recent years threadfin shad in 

 Wahiawa Reservoir, Oahu, have become suf- 

 ficiently abundant to make large-scale fishing 

 tests possible. 



METHODS AND MATERIALS 

 Experimental Fishing 



Fishing took place during five different 

 cruises of the research vessel Charles H. 

 Gilbert in Hawaiian waters in 1967 and 1968 

 (Table 1). Nehu, the regular skipjack tuna bait, 

 were used as a control, and fishing data were 

 collected from 37 of 101 schools of skipjack 

 tuna encountered. On the first three cruises 

 both threadfin shad and nehu were chummed 

 alternately for 3- to 5-min periods on each of 

 nine schools of skipjack tuna fished. On the 

 latter two cruises the two bait species were 

 alternated among 28 schools of skipjack tuna, 

 except on three occasions when operational 

 problems prevented alternation of bait. 



Fishing was carried out in the following 



