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when it expanded its po1e-and-l ine operations offshore along the Kuroshio 

 front. The developing Japanese coastal gill net fishery has also begun 

 reporting catches of North Pacific albacore, as have the longline fleets of 

 Taiwan and Korea which have recently begun fishing in the North Pacific. 



III. STATUS OF THE STOCKS 



The status of North Pacific albacore was assessed by participants 

 attending the Fifth North Pacific Albacore Workshop held in June and July 

 1980. 



I II. A. Stock Structure 



The Pacific albacore population is assumed to be composed of north 

 and south stocks separated near the equator. The complex migratory 

 patterns of juveniles within the north stock have led some scientists to 

 hypothesize that more than one stock exists in the North Pacific, but not 

 enough is currently known about the migration of adults to substantiate 

 this hypothesis; therefore, a single north stock is assumed. 



III.B. Stock Assessment and Fishery Evaluation 



III.B.l. Trends in Catch-per-Unit-Effort 



Because of difficulties associated with standardizing 

 effort among the different gears, an overall index of abundance for the 

 entire fishery is not available. However, catch-per-unit-effort (CPUE) for 

 the Japanese surface, Japanese longline, and U.S. surface fisheries (Figure 

 4) have all shown decreasing trends in recent years. 



III.B. 2. Results of Production Model Analysis 



Production model analysis is also problematic due to the 

 effort standardization problem. An analysis prepared for the albacore 

 workshop (Figure 5) predicted a maximum sustainable average yield (MSAY) of 

 between 104,000 and 236,000 mt. Although it is impossible to select a 

 "best" value, the midpoint of 170,000 mt may be reasonable. 



III.B. 3. Results of Yield-per-Recruit Analysis 



Yield-per-recruit (Y/R) analyses indicate that the 

 expansion of the Japanese surface fishery in the early 1970 's decreased the 

 Y/R for the entire fishery (Figure 6). While the Y/R for the Japanese 



