ties all the way across the breadth of the Pacific Ocean, 

 including the site of the rich eastern Pacific yellowfin tuna 

 fishery. 



Matsumoto thinks that the tropical Pacific has large skip- 

 jack tuna resources to the west of the 180th meridian. This 

 area is at present fished only very lightly by the fleet based 

 in the Trust Territory of the Pacific Islands. Before World 

 War II, it supplied Japan with a substantial catch of skip- 

 jack tuna in those islands. 



The feeble larvae are caught by plankton nets ; but when 

 the tunas enter the next stages of their lives, as juveniles 

 able to dart about under their own power, they become 

 elusive indeed. Tens of thousands of larvae have been taken 

 on research cruises; captures of juvenile tunas can be num- 

 bered in the hundreds, says Bruce E. Higgins, who reviewed 

 the data on juveniles for the 12th Session of the Indo-Pacific 

 Fisheries Council. 



Higgins' findings complement Matsumoto's. Juvenile 

 yellowfin tuna are more common than skipjack tuna in the 

 eastern tropical Pacific, but have been reported from fewer 

 locations in the central and western Pacific. Skipjack tuna 

 juveniles were by far the most plentiful, accounting for well 

 over half the total of all juveniles. 



Were they not eaten by larger fishes, juvenile tunas would 

 be almost unknown to science. No net used today — particu- 

 larly the standard 1-m. net (fig. 14) that is used to sample 

 the plankton — catches them as often as do larger tunas 

 and billfishes. This fact is strikingly shown when locations 

 of capture are mapped. Almost all the small tunas are 

 recovered at fishing ports, that is, are found in the stomachs 

 of larger fishes landed there. Distribution maps thus prob- 



FIGURE 14 The 1-m. net is fhe standard collecting device used to 

 somple the drifting plants and animals ot the sea, the plankton. 

 "One meter" refers to the diometer of the mouth of the net. Drifting 

 specimens ore taken by the net, but very few of the active juvenile 

 forms of the tunas have ever been taken in plankton tows. 



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