that meridian. 



After 1956 the Japanese longline fishery in the 

 eastern Pacific expanded rapidly and at the present 

 this fleet is fishing in all areas of the eastern Pacific 

 in which billfish and tunas are found. 



In addition to their commercial longline opera- 

 tion, the Japanese used longline gear to investigate 

 the complex oceanic environment during a number 

 of scientific cruises devoted to fishery biology and 

 exploratory fishing. The results of these investiga- 

 tions are well documented in trade as well as scien- 

 tific journals. Some of the latter are: Suda and 

 Schaefer, 1965; Kume and Schaefer, 1966; Kume 

 and Joseph, 1969a and 1969b; Anonymous, 1972. 



Commercial longline vessels of the Republics of 

 Korea and China also fish for billfish in the eastern 

 Pacific. The vessels of these two countries first 

 began their operations in the eastern Pacific in the 

 mid- 1 960' s. Documentation of these fisheries is not 

 complete and statistical coverage is low (Anony- 

 mous, 1968a, 1970a, and 1971a). 



In 1965 the U.S.S.R. conducted two longline 

 cruises in the eastern Pacific, mostly in the Gulf of 

 Tehuantepec, Mexico. Results are given in Chernyi 

 (1967); Novikov and Chernyi (1967); and Yurov 

 and Gonzalez (1971). The latter report also dis- 

 cussed the results of a Cuban longline expedition 

 for billfishes and tunas in the eastern Pacific in 1967 

 (Bravo and Gonzalez. 1967). 



During Cruise 14 of the RV Anton Bruun, oper- 

 ated by the U.S. National Science Foundation, 

 longlining was conducted off Chile and Peru in 1966 

 (Shomura) 2 . 



Experimental longline fishing for swordfish off 

 California and Mexico was conducted by the U.S. 

 Bureau of Commercial Fisheries in 1968. Results 

 of these investigations were given by Kato (1969). 



Most recently, in 1970, personnel of the Scripps 

 Institution of Oceanography conducted experimen- 

 tal longline fishing for tunas and billfish in the east- 

 ern Pacific Ocean to the west of Baja California 

 (Blackburn, Williams, and Lynn) 3 . 



In this report the literature mentioned above is 



2 Shomura, R. S., unpublished report. Cruise Report, Re- 

 search Vessel Anion Bruun, Cruise 14. Special Report No. 4, 

 Marine Laboratory Texas A&M University, Galveston, Texas, 

 38 pp. (pages 7 through 38 not numbered). 1966. 



3 Blackbum, M., F. Williams, and R. Lynn, unpublished re- 

 port. The bluefin tuna approach region off Baja California, pp. 

 17-19 in: Progress Report — Scripps Tuna Oceanography Re- 

 search (STOR) Program— Report for the year July 1, 1969 -June 

 30, 1970. Univ. Calif., Scripps Inst. Oceanogr., IMR Ref. 

 (71-3). SIO Ref. 70-32:24 pp. 1970. 



utilized to discuss the distribution of billfishes in the 

 eastern Pacific Ocean. Data on catch and effort for 

 the Japanese longline fishery, which captures ap- 

 proximately 85% of the billfish taken in the eastern 

 Pacific, are used to study trends in relative abun- 

 dance, effort, and catch. In the final section prob- 

 lems relevant to scientific research on billfish are 

 discussed. 



THE DATA— SOURCES 

 AND PROCESSING 



The major source of the information used in this 

 report is from the Japanese longline fleet. These 

 vessels maintain logbook records of their fishing 

 operations which are submitted to the Fisheries 

 Agency, Ministry of Agriculture and Forestry, 

 Japan. The data are printed each year in the Annual 

 Reports of Effort and Catch Statistics of the Re- 

 search Division, Fisheries Agency of Japan 

 (Anonymous 1968b, 1969b, 1970b, 1971b, and 

 1972). Catches expressed incumbers offish are re- 

 ported by species, areas of 5 geographical degrees 

 on a side, month, type of operation, size of vessel, 

 type of bait utilized, number of sets and number of 

 hooks. Data from 1966 through 1970 (Anonymous, 

 1968b, 1969b, 1970b, 1971b, and 1972) were taken 

 from the Fisheries Agency's Annual Reports; prior 

 to that time the reports of Suda and Schefer (1965), 

 Kume and Schaefer (1966) and Kume and Joseph 

 (1969a), were used. Details of data collection, han- 

 dling, and logbook coverage are given in these re- 

 ports. 



All logbook catch and effort data were stored on 

 magnetic tape and then used to generate tabulations 

 of catch and effort in convenient format for 

 analysis. 



In order to compute total catch for the Japanese 

 longline fishery, the recorded logbook catch was 

 adjusted by the reciprocal of the percent coverage 

 which the logbooks represented of the total catch. 

 These percentages, which vary between 60 and 90, 

 are given in the relevant reports listed above. 



The saury (Cololabis saira) has been the princi- 

 pal bait used by the Japanese longline fishery but in 

 recent years there has been increased use of other 

 types of bait. Since 1964 some of the vessels operat- 

 ing off the west coast of Baja California, Mexico 

 have used squid (Todarodes paciftcus) for bait. At 

 least through 1966 these vessels were fishing mainly 

 for swordfish, usually at night. It is unknown 

 whether this type of fishing was done subsequent to 



311 



