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I. DESCRIPTION OF THE FISHERY 



I. A. History of the Fishery 



Yellowfin tuna ( Thunnus albacares ) in the western Pacific Ocean 

 (west of ca. 150° W longitude) is caught primarily by longline gear; 

 smaller amounts are taken by pole-and-1 ine, purse seine, and other surface- 

 fishing gear. The longline fishery that now extends completely across the 

 Pacific Ocean between approximately 45° N and 45° S latitude is an 

 outgrowth of the Japanese longline fishery, which was generally confined to 

 the western Pacific before World War II. The Japanese longline fishery 

 quickly expanded eastward after the war and reached the American continents 

 in 1964 (Figure 1). Longline vessels from Taiwan joined the fishery in 

 1962 and those from South Korea, in 1965 (Suzuki et al . 1978). Because the 

 longline fishery extends completely across the Pacific Ocean, for the 

 purpose of this report yellowfin tuna are considered for the entire Pacific 

 Ocean insofar as they relate to the longline fishery. 



Japan, Taiwan, and the Philippines have surface fisheries for 

 yellowfin tuna in the western Pacific. Australia, Fiji, Gilbert Islands, 

 Papua New Guinea, New Zealand, and French Polynesia also show landings of 

 yellowfin tuna (Food and Agriculture Organization of the United Nations 

 [FAO] 1977, 1978). 



The U.S. (Hawaii) has a small longline fishery and also a surface 

 fishery for yellowfin tuna in the western Pacific. 



I.B. Trends in Catch and Effort 



The total annual catch of yellowfin tuna (all gear combined) ranged 

 from 28,586 to 193,518 mt from 1952 to 1977 in the western Pacific (Table 

 1). The catches made in the various Japanese fisheries (which totaled 

 28,118 to 101,480 mt from 1952 to 1977) contributed the largest amount to 

 the western Pacific annual total (Table 2). The bulk of the Japanese total 

 annual catch is taken by longline vessels over 20 gross tons. Table 2 also 

 shows the catch by gear, for other countries fishing yellowfin tuna in the 

 western Pacific 



The total western Pacific catch of yellowfin tuna peaked in the 

 mid- 1960 's (with a high of 110,458 mt in 1966), declined slowly to 76,121 

 mt in 1971, then increased rapidly to levels higher than that in the 

 1960's, reaching 193,518 mt in 1977 (Figure 2). Reported catches from the 

 Philippines since 1974 (Table 2) account for the increase in the total 

 recorded catch of yellowfin tuna in recent years (FAO, in press). 



The total (Japan, Korea, Taiwan) fishing effort for yellowfin tuna 

 in the Pacific generally showed an increasing trend from 75 million 



