with the two baits during 1967 and 1968 aboard 

 the research vessel Charles H. Gilbert . 

 Threadfin shad and nehu were alternated among 

 25 of 28 skipjack schools fished and alternated 

 every 3 to 5 min on each of the other 9 skipjack 

 schools. 



2. When bait was alternated among schools, 

 the following catch data were recorded. Aver- 

 age number of skipjack tuna caught per minute: 

 shad - 7.5; nehu - 8.2. Number of skipjack tuna 

 caught: shad - 1,428; nehu - 1,597. Average 

 number of skipjack tuna caught per school: 

 shad - 102; nehu - 114. Average weight of 

 skipjack tuna caught per school: shad - 344 kg; 

 nehu - 485 kg. Average duration of fishing per 

 school: shad - 10.8 min; nehu - 15.4 min. 

 Percent of schools chummed that were suc- 

 cessfully fished: shad - 50.0; nehu - 35.9. 



3. When bait was alternated on the same 

 school, the following catch data were recorded. 

 Average number of skipjack tuna caught per 

 minute: shad - 9.1; nehu - 7.7. Number of 

 skipjack tuna caught: shad - 1,248; nehu - 998. 

 Average number of skipjack tuna caught per 

 school: shad - 139; nehu - 111. Average weight 

 of skipjack tuna caught per school: shad - 461 

 kg; nehu - 314 kg. Percent of schools respond- 

 ing to first bait chummed: shad - 12.0; nehu - 

 55.6. 



4. Nonparametric statistical tests showed no 

 significant differences between threadfin shad 

 and nehu in the following categories of catch 

 data: skipjack tuna catch per minute, catch per 

 minute of skipjack tuna <4.5 kg, catch per min- 

 ute of skipjack tuna >4.5 kg, number of skipjack 

 tuna caught per school, duration of fishing per 

 school, and weight of skipjack tuna caught per 

 school. 



5. Underwater photographs taken automati- 

 cally indicated shad concentrated skipjack tuna 

 in the fishing area equally as well as nehu. 



6. Threadfin shad and nehu have similar 

 swimming behavior when used as chum for 

 skipjack tuna fishing. 



7. Bait-sized threadfin shad occur in Hawai- 

 ian freshwater impoundments during the peak 

 months of skipjack tuna fishing. They are 

 hardy, readily handled in large numbers and 

 easily acclimated to salt water. 



ACKNOWLEDGMENTS 



I would like to acknowledge the capable as- 

 sistance of the captain and crew of the Charles 

 H. Gilbert , without whose help the shad could 



not have been captured or tested at sea, and of 

 my colleagues Reginald M. Gooding, Eugene L. 

 Nakamura, Earl Murchison, John J. Naughton, 

 and Randolph K. C. Chang, for their unstinting 

 cooperation in conducting the experiments and 

 making bait observations at sea. I thank Richard 

 N. Uchida and Eugene L. Nakamura for review- 

 ing the manuscript. 



LITERATURE CITED 



BROCK, V. E., and R. N. UCHIDA. 



1968. Some operational aspects of the Ha- 

 waiian live-bait fishery for skipjack tuna 

 ( Katsuwonus pelamis ). U.S. Fish Wildl. 

 Serv., Spec. Sci. Rep. Fish. 574, 9 p. 



HIDA, T. S. 



1970. Surface tuna schools located & fished 

 in equatorial eastern Pacific. Commer. 

 Fish. Rev. 32(4): 34-37. 

 HIDA, T. S., and D. A. THOMSON. 



1962. Introduction of the threadfin shad to 

 Hawaii. Progr. Fish-Cult. 24: 159-163. 

 ROYCE, W. F., and T. OTSU. 



1955. Observations of skipjack schools in 

 Hawaiian waters, 1953. /U.S./ Fish Wildl. 

 Serv., Spec. Sci. Rep. Fish. 147, 31 p. 



SHANG, Y. C. 



1969. The skipjack tuna industry in Hawaii: 

 Some economic aspects. Univ. Hawaii, 

 Econ. Res. Center, 59 p. 



SIEGEL, S. 



1956. Nonparametric statistics for the be- 

 havioral sciences. McGraw-Hill, New 

 York, 312 p. 



UCHIDA, R. N. 



1967. Catch and estimates of fishing effort 

 and apparent abundance in the fishery 

 for skipjack tuna ( Katsuwonus pelamis ) 

 in Hawaiian waters, 1952-62. U.S. Fish 

 Wildl. Serv., Fish. Bull. 66: 181-194. 

 YUEN, H. S. H. 



1959. Variability of skipjack response to 

 live bait. U.S. Fish Wildl. Serv., Fish. 

 Bull. 60: 147-160. 



1969. Response of skipjack tuna ( Katsuwonus 

 pelamis ) to experimental changes in 

 pole-and-line fishing operations. In A. 

 Ben-Tuvia and W. Dickson (editors), Pro- 

 ceedings of the FAO Conference on Fish 

 Behaviour in Relation to Fishing Tech- 

 niques and Tactics, Bergen, Norway, 19- 

 27 October 1967. FAO (Food Agr. Organ. 

 U.N.) Fish. Rep. 62, 3: 607-618. 



GP O 999^402 



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