LONGLINE FISHING FOR TUNA IN THE CENTRAL EQUATORIAL PACIFIC, 1954 



By 



Edwin S. Iversen, Fishery Research Biologist 



and 



Howard O. Yoshida, Fishery Aid 

 Pacific Oceanic Fishery Investigations 

 Honolulu, T. H. 



One of the chief goals of the Pacific Oceanic 

 Fishery Investigations (POFI) is to evaluate the 

 equatorial Pacific tuna resources and to make 

 the results of this appraisal available to Ameri- 

 can fishermen. In order to locate the regions 

 of greatest tuna abundance and define their 

 boundaries it has been necessary to do experi- 

 mental fishing throughout vast areas of the 

 equatorial Pacific. Our principal sampling tool 

 has been the longline, which is used commer- 

 cially to great advantage by the Japanese. Our 

 research program has also of necessity included 

 an evaluation of the longline method and of means 

 of increasing its efficiency. 



The present report is the fifth in a series 

 and includes information obtained during experi- 

 mental and commercial operations in the equa- 

 torialarea in 1954. The earlier reports (Murphy 

 and Shomura 1953a, 1953b, 1955, and Shomura 

 and Murphy 1955) included processed data from 

 cruises of 1950 through 1953, with some infor- 

 mation from Japanese commercial fishing oper- 

 ations. The highlights of the 1954 fishing are: 



(1) First commercial effort by American 

 fishermen based on POFI research. 



(2) First use of steel-mainline gear. 



(3) Continued fishing for nearly 1 year in 

 the Line Islands area, mainly near 

 Christmas Island. 



(4) Sharp difference in seasonal catch rates 

 from previous years. 



Longline catch statistics for the central 

 equatorial Pacific during 1954 came from many 

 sources. There were 2 POFI research cruises 

 and 11 fishing trips by 6 American commercial 

 vessels to the central equatorial region during 

 the year. The John R. Manning (cruise 20) 

 operated entirely within the Line Islands area; 

 the Charles H. Gil bert (cruise 15) fished three 

 north-south lines of stations, one close to Baja 



California at 119°W. longitude, one that crossed 

 the Equator on 110°W. longitude, and a third 

 which crossed the Equator on 155°W. longitude. 

 The American commercial vessels operated in 

 the vicinity of the Line Islands . Two of the com- 

 mercial cruises made during 1954 were of imme- 

 diate interest to the fishing industry so a general 

 account of the venture was published (Iversen 

 and Murphy 1955). In addition, longline fishing 

 was initiated at American Samoa. The overall 

 operation from January to April 1954 was re- 

 ported by Van Campen (1954); the catch rates 

 will be discussed in this report. Lastly, we 

 have utilized the available data from Japanese 

 longline fishing near the Equator. 



In order to avoid needless repetition the 

 present report does not include as detailed an 

 analysis of the 1954 fishing results as was pre- 

 sented for the years 1950 through 1953 in the 

 four previous numbers of the series. For in- 

 stance, little space will be devoted in this re- 

 port to the discussion of tuna other than yellow- 

 fin since other species were not taken in sufficient 

 quantity to be of commercial interest. Operational 

 details and the complete catch records for fishing 

 cruises during 1954 are given in the Appendix. 

 For the sake of simplicity, only the vernacular 

 names of the various species in the catch will be 

 used in this report. The scientific name for 

 each species is listed in table 1 of the Appendix. 



ACKNOWLEDGMENTS 



Appreciation is extended to the captains and 

 crewmen of both the commercial and POFI ves- 

 sels for their cooperation and to the scientific 

 personnel who made the observations, in many 

 instances under adverse conditions. Deserving 

 of special thanks are the following commercial 

 vessel captains and owners: S. Jangaard, L. 

 Jangaard, A. Ottness, E. Oswald, H. Sperling, 

 and J. Parsons. The bathythermograph tem- 

 perature sections and the Christmas Island tem- 

 perature graph were prepared by T. S. Austin. 



