of fish taken in the various unit areas. Landings by 

 weight can be estimated from the data along with 

 average body weight data. 



Catches per unit of fishing effort: The catch per unit 

 of effort (CPUE) can be obtained in terms of catch in 

 numbers per 100 or 1,000 hooks fished. Strasburg 

 (1970) studied year-to-year changes in CPUE of 

 billfishes in the Pacific by analyzing the 1953-63 

 Japanese longline data for quadrangles measuring 20° 

 of latitude and longitude. He noted a progressive 

 decline over the years in the CPUE for the striped 

 marlin of western and central South Pacific (lat. 20°- 

 40°S) areas. Strasburg (1970) concluded that while 

 some workers have attributed the decline in CPUE to 

 heavy fishing, "It is impossible to determine its real 

 cause without more information on various biological 

 features related to migration, reproduction, age, and 

 year classes." 



Honma and Suzuki (1969) studied the apparent 

 abundance of striped marlin in the principal fishing 

 grounds in the Pacific (northwestern Pacific, eastern 

 Pacific, and waters east of Australia) for the years 

 1960-66. They noted no apparent trends in CPUE in 

 the northwestern Pacific and eastern Pacific grounds. 

 On the other hand, for waters east of Australia, they 

 reported a definite decreasing trend; the CPUE has 

 been at a low level of around 0.1 fish per 100 hooks 

 since 1964. 



Of the striped marlin in the Indian Ocean, Kikawa 

 et al. (1969) examined the annual changes in CPUE 

 (number of fish per 1,000 hooks) based on data for the 

 years 1962-67. They reported CPUE of about 0.6 fish 

 per 1,000 hooks between 1962 and 1964, followed by an 

 increase to about 1.0 in 1965-67. The authors conclud- 

 ed that "An increasing trend in the CPUE for striped 

 marlin in this period may probably represent the in- 

 crease in effectiveness in catching fish." 



Fishing effort per unit area: Figure 8 shows the dis- 

 tribution of fishing effort of the Japanese tuna 

 longline vessels in 1970. The effort, in terms of 



numbers of hooks fished, is shown by 5° quadrangles. 

 If we examine the data along with catch per unit 

 area data of striped marlin (Fig. 9) it is apparent that 

 the relatively large fishing effort in the eastern Pacific 

 off Mexico and Ecuador is principally related to pur- 

 suit of striped marlin in those areas. 



Total fishing intensity : The total fishing effort of the 

 Japanese longline vessels in recent years (1965-69) for 

 the Pacific and Indian oceans is estimated at about 

 400 million hooks fished per year. The efforts by areas 

 are given in Table 5 (see 4.23). 



Since 1963 there has been a significant increase in 

 fishing effort in the eastern Pacific region. Correspond- 

 ingly the fishing grounds for striped marlin also has 

 increased during this period. 



In the South Pacific region, however, effort has 

 decreased from about 100 millin hooks in 1965-66 to 

 around 70 million hooks beginning in 1967. 



5.42 Selectivity 



Small striped marlin under 80 cm eye-fork length 

 are virtually never taken by longline. 



Furukawa et al. (1958) have reported that striped 

 marlin taken by harpooning in the East China Sea 

 fishing grounds are relatively heavier (higher fatness 

 index) than fish taken by longline. 



5.43 Catches 



Total annual yields: The FAO "Yearbook of fishery 

 statistics" reports the total annual yields of striped 

 marlin; Table 8 summarizes the 1970 catch (FAO, 

 1971). The recent total annual landings of striped 

 marlin have been around 25,000 tons from the Pacific 

 and Indian oceans. 



Total annual yields from different fishing 

 grounds: As seen in Table 8, the striped marlin 

 catches are high in the eastern Pacific; the catch from 

 this area comprises about one-half of the total Pacific 



Table 8. — Catches of striped marlin by fishing areas for 1964-70. (From FAO, 



1971.) 



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