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FIGURE 15. A new type of net will be used by the Laboratory in 

 Honolulu in an ottempt to capture juvenile tunos ot seo. This large 

 trawl, with o mouth opening of obout 65 feet, is designed to be towed 

 at a specified depth in the woter The mesh is so small that the 

 juveniles, which are no more fhon o few inches long, connot escape. 



ably misrepresent the actual distribution of juveniles in the 

 ocean. 



Seeking a better method for the collection of the fish, 

 Higgins consulted with the Bureau's Exploratory Fishing 

 and Gear Research Base, Seattle, which supervised the 

 design and construction of a new type of net (fig. 15). It 

 is very large, with a mouth which when open is big enough 

 to engulf a six-story building. The mesh is small, so that 

 the juveniles cannot escape. It can be towed at middepths. 

 This new trawl net will be tested on cruises of the research 

 vessel Townsend Cronnvcll during 1967. 



Large amounts of statistics on the tunas become available 

 only after the fish enter the commercial catch. The several 

 fisheries of the Pacific draw on the tunas at different stages 

 of their life. Statistics from the catch allow fishery scien- 

 tists to determine what elements of the population support 

 which fisheries. Sharp differences appear: Off Japan, for 

 example, the bigeye tuna taken by the longlines are shorter 

 (and presumably younger) than those taken in equatorial 

 waters. Bruce E. Higgins, who has reviewed the records of 

 lengths of fish in the several fisheries, says the sizes also 

 change markedly from west to east. The larger bigeye tuna 

 are caught in the east. Albacore taken near Japan are 

 mostly 20 to 30 inches long; those near Hawaii, much 

 longer. Yellowfin tuna in the western Pacific are 30 to 40 

 inches long, and those of the open seas slightly larger than 

 those caught closer to land. In the eastern Pacific, where 

 the yellowfin tuna are the object of a large surface fishery, 

 smaller fish are caught; the average length is about 23 

 inches, but the deep-swimming yellowfin tuna caught by 

 longlines are very large. Skipjack tuna in the eastern Pacific 

 are small and young. In the central Pacific, several size 

 groups are present. Larger fish (more than 20 inches long) 

 are invariably the preponderant type in the peak summer 

 catches in Hawaii. 



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