rates from the northwest-central Pacific to the 

 southeast Pacific. Hook rates remain high in the 

 southeast through the southern summer, then shift 

 northward again in the southern fall. It is the south- 

 eastern shift in apparent abundance which contrib- 

 utes to the high catch rates in the eastern Pacific 

 area of lat. 15°-25°S, long. 110°-130°W during the 

 southern summer. 



On the basis of the distribution data examined in 

 this report it would be impossible to determine 

 whether the blue marlin of the eastern Pacific are 

 from a single stock which is separate from those 

 farther west. However Anraku and Yabuta (1959), 

 who examined more extensive information, consid- 

 ered the blue marlin of the Pacific to be a single 

 population which undergoes widespread intermin- 

 gling. 



Black Marlin 



Black marlin are caught in negligible quantities in 

 the eastern Pacific Ocean. Their greatest abun- 

 dance is in the southwestern part of the Pacific 

 Ocean near eastern Australia and New Guinea. 

 Their abundance decreases rapidly toward the east, 

 and is very low east of long. 150°W. Hook rates in 

 the eastern Pacific are consistently less than one 

 fish/ 1,000 hooks. 



Because of the low catch rates in our area of 

 study quarterly charts are not shown for black mar- 

 lin. However an average annual distribution of 

 hook rates by 5-degree areas for the years 1956-1970 

 is shown in Figure 9. The area in which black mar- 

 lin are generally captured in the eastern Pacific can 

 be defined as that area lying within a diagonal line 

 extending from about the middle of Baja California 

 southwest to where the 130th meridian intersects 

 the lat. 20°N line of latitude, and a diagonal line 

 extending from the Peruvian shore at about lat. 10°S 

 to where the 130th meridian is intersected by the 

 lat. 35°S line of latitude. 



Howard and Ueyanagi (1965) discuss the general 

 distribution of black marlin throughout the Pacific 

 and Indian Oceans. For the eastern Pacific they 

 utilize information from subsistence and sports 

 fisheries to describe the nearshore seasonal dis- 

 tribution. 



They report black marlin to occur as far south as 

 northern Chile and in the north to about Cape San 

 Lucas. In their discussions of the population struc- 

 ture they consider the black marlin of the eastern 

 Pacific to be a separate stock from those farther 



Figure 9. — Annual average number of black marlin 

 caught per 1.000 hooks by Japanese longline vessels in 

 the eastern Pacific by 5-degree areas, 1956-1970. 



west. They also suggest that the fish which occur 

 off southern Peru and northern Chile may be dis- 

 tinct from those taken near shore but farther north. 



Sailfish and Shortbill Spearfish 



The quarterly distribution of sailfish and shortbill 

 spearfish is shown in Figure 10, averaged over the 

 years 1956-1970. These two species are not sepa- 

 rated in the figure because most commercial long- 

 line vessels do not differentiate between them in 

 their catch records. Some idea of the relative dis- 

 tribution of the two species can be obtained, how- 

 ever, by examining the results of exploratory and 

 research cruises in the eastern Pacific Ocean. Dur- 

 ing such cruises the two species are differentiated in 

 catch records. In their analysis of the billfish fishery 

 of the eastern Pacific, Kume and Joseph (1969a, 

 1969b), used the results of nine exploratory cruises 

 to differentiate the geographical distribution of the 



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