FIGURE 16 Brian J Rothschild of the BCF Loborotory in Honolulu 

 has hypothesized that the skipiack tuna of the costern Pacific ore 

 spawned in equatorial woters of the centrol Poofic. They enter the 

 eastern Pacific fishery at on age of about I year but remain there only 



are correct (fig. 16). Very briefl.v. these hypotheses said 

 that the eastern Pacific stock of sl\ipjack tuna is spawned 

 somewhere in the central Pacific, that the fish enter the 

 eastern Pacific at about 1 year old but remain there no more 

 than a few months, that at about 18 months they return to 

 spawn in the central equatorial Pacific, and that most of 

 them are never caught in any fishery. Evidence to support 

 the main points of these hypotheses is plentiful, but direct 



few months. Those that are not caught return to the central Pacific 

 and spawn. This older stock is not substantially fished at present. 

 Rothschrld sees o similar movement of the fish in the Southern 

 Hemisphere. 



proof is lacking and will remain so until more is known 

 about certain aspects of the life history of the fish. 



One of these aspects is tied into the probability of the 

 existence of several subpopulations of skipjack tuna. It has 

 now been shown, through the work of the Laboratory in 

 Honolulu, that subpopulations of skipjack tuna are detect- 

 able and that several exist in the central Pacific. These 

 groups of skipjack tuna do not interbreed. Lucian M. Sprague 



25 



