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II. THE NATURE AND SIGNIFICANCE OF U.S. AND FOREIGN 

 PARTICIPATION IN THE FISHERY 



United States tuna processors utilize domestic and foreign-caught 

 bigeye tuna for canning as light meat tuna. The highest recorded U.S. 

 Atlantic bigeye tuna catch (865 mt) occurred in 1974 (Figure 6). In 1979, 

 the U.S. catch was 200 mt. The amount imported is difficult to determine 

 since bigeye and yellowfin tuna are not separated in import reports. The 

 preliminary U.S. catch of yellowfin and bigeye in 1980 (preliminary figures 

 do not separate catches of the two species) was 8,500 mt. 



U.S. participation in the Atlantic fishery (which is a multi-specific 

 tropical tuna fishery catching bigeye, yellowfin, and skipjack tuna) is not 

 expected to increase above 1980 levels (6 vessels). Future foreign 

 participation in the fishery is difficult to estimate with any degree of 

 certainty but is not anticipated as long as the fisheries continue 

 operating within their current geographical boundaries and current fishing 

 methods. 



III. STATUS OF THE STOCKS 



I II. A. Stock Structure 



Bigeye tuna are distributed throughout the Atlantic Ocean (Figure 

 1). Scientists have hypothesized separate north and south Atlantic stocks. 

 Evidence for this includes a decline in hook rates in the equatorial 

 Atlantic and preliminary evidence of separate spawning areas, one in the 

 northern and one in the southern tropical areas. 



Recapture of bigeye tuna tagged in the eastern Atlantic indicate 

 that the fish generally remained in areas of tagging off Dakar and Point- 

 Noire, except for a single fish that exhibited northward migration from the 

 Gulf of Guinea to the area off Dakar after one year. Since evidence of 

 either a single or separate northern and southern stocks is inconclusive, 

 two hypotheses are used in stock assessments: 1) a single Atlantic stock, 

 and 2) two independent stocks separated at approximately 5° N latitude. 



