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ter of 1965 the fishery was shared by 62 vessels from Japan, 

 30 from Korea, and 13 from Taiwan. 



Tuna Larvae and Young 



If all the eggs spawned by a single female yellowfin tuna 

 in one season were to survive the vicissitudes of life in the 

 sea, at maturity they alone would provide a catch of about 

 half a million tons of fish. Most fishes have this prodigal 

 reproductive potential : It is the mechanism that maintains 

 the breed. 



It would be useful if tuna eggs (fig. 12) could be identified 

 as to species, but they cannot be. All tunas except the 

 albacore can be identified at the next stage of their life, 

 the larval. The distribution of larvae pictures the areas and 

 time of spawning of the tunas. For the Governor's Confer- 

 ence, Walter M. Matsumoto reviewed all available evidence 

 on the occurrence of tuna larvae in the Pacific. 



The most intensively investigated sector of the Pacific is 

 that narrow strip along the west coast of North America 

 which is the site of the field studies of the California Coop- 

 erative Oceanic Fisheries Investigations. Almost 16,000 

 plankton samples were taken there in 1951-60. This area, 

 however, is nearly barren of tuna larvae. Far more produc- 

 tive of larvae have been the region west of Central America, 

 sampled mostly by the Inter-American Tropical Tuna Com- 

 mission, and the central Pacific, where the Laboratory in 

 Honolulu has made several thousand plankton tows. 



Matsumoto found that skipjack tuna larvae were re- 

 markably sparse in the eastern Pacific (fig. 13). They have 

 been captured widely and often in the central Pacific from 

 lat. 30° N. to 20° S., and presumably (data are very sketchy) 

 are frequently taken in the western Pacific, where their 



FIGURE 12. Immature eggs taken from a female skipjack tuna. Most 

 of those in this photomicrogroph ore obout one one-hundredth of on 

 inch in diameter. The larger circles ore eggs thot ore further devel- 

 oped thon the others. 



20 



