FISHERY BULLETIN: VOL. 81, NO. 1 



Table 1.— Total number of months in which bluefin tuna catch exceeded 50 t 

 within a 1° area of latitude and longitude for the years 1957-69 and 1974. Each 

 latitude and longitude indicates the southeast corner of the 1° area of considera- 

 tion. Asterisks indicate the coastline. 



Table 2.— Total landings of bluefin tuna by commercial (in 

 metric tons (t)) and sport fisheries (no. fish) in the eastern 

 North Pacific Ocean, 1918-81. Asterisks indicate no data 

 available. 



clusively by the San Pedro wetfish fleet, which 

 seasonally targets fishing effort on sardines, an- 

 chovies, mackerel, bonito, bluefin tuna, and 

 other fishes, depending on fish availability, mar- 

 ket price, and market demand (cannery orders). 

 During the second period, about 1950-present, 

 annual landings increased to 16,846 t in 1966, 

 then declined to 1,016 1 in 1981, averaging 9,076 1 

 for the period. At the beginning of this period, 



many of the high-seas boats that had converted to 

 purse seining began catching large numbers of 

 bluefin off Baja California, although they target- 

 ed their fishing on yellowfin tuna, Thunnus alba- 

 cares, and skipjack tuna, Katsuwonus pela- 

 m is. 



Two sources of data were used in summarizing 

 total catch by area. The first, landings reported 

 by CFG, separates pounds landed in California 

 for 1918-79 into those caught in California wa- 

 ters and those caught south of California waters. 

 These data reveal an overall decreasing trend in 

 bluefin catch north of the international border; 

 and, until about 1963, there was an overall in- 

 creasing trend in total catches south of the inter- 

 national border (Fig. 2). 



The second source of catch data also includes 

 effort information and was compiled into a data 

 base for summary and analysis. These data, rep- 

 resenting about 87% of the catch during the peri- 

 ods 1954-69 and 1971-74, came from summaries 

 of skippers' logs, from interviews with skippers 

 and engineers, from CFG landing receipts, and 

 from IATTC summaries of the high-seas fleet. 

 Catch and effort in the data base are recorded by 

 1° areas of latitude and longitude. For this study, 

 one boat-day or part of a boat-day of effort is as- 

 signed to a seiner for each day or partial day of 

 purse seining or searching for tuna in the bluefin 

 fishing range (north of lat. 22°N) during months 

 in which bluefin were caught. Catch data, sum- 

 marized by areas north and south of lat. 32°N 

 (the parallel nearest the international border), 

 show trends similar to the reported California 

 landings for the same years (Fig. 3). 



For comparison with the CFG reported Cali- 

 fornia landings and for future consideration of 

 the effects of Mexican regulations concerning 



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