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I. DESCRIPTION OF THE FISHERY 



I. A. History of the Fishery 



Commercial longline fishing for albacore ( Thunnus alalunga) , bigeye 

 tuna (T. obesus) , and yellowfin tuna (T. albacares ) in the Indian Ocean, 

 started" after World War II although exploratory fishing by Japanese vessels 

 in the early 1930's had indicated the presence of tunas in the eastern 

 Indian Ocean. Intensive commercial longline fishing in the Indian Ocean 

 began in 1952 in the eastern sector and rapidly expanded westward to reach 

 the African coast by 1956 (Figure 1) (Nakamura et al . 1956; Kikawa et al . 

 1969). Countries currently maintaining longline fleets in this area 

 include Japan, Korea, Taiwan, U.S.S.R., and Sri Lanka. Vessels from 

 Australia, India, Madagascar, Maldives, Pakistan, Sri Lanka, Democratic 

 Republic of Yemen. Seychelles, and Oman catch surface yellowfin tuna 

 (Wetherall et al.M. 



The surface skipjack tuna ( Katsuwonus pel amis) fishery in the 

 Indian Ocean is still relatively undeveloped. Most of the catches of 

 skipjack tuna, and a smaller but growing proportion of the catches of 

 yellowfin tuna, are made in localized fisheries along the coastline of the 

 various countries bordering the ocean and around the many island groups. 

 The origins of these fisheries are obscure and their historical accounts 

 are few and fragmentary.. In Sri Lanka (Ceylon), skipjack tuna are taken 

 by trolling gear, drift nets, and pole-and-1 ine. Use of the pole-and-1 ine 

 method dates back to 1919 in Sri Lanka and in Minicoy, Laccadive, and 

 Maldive Islands to 1909 (Sivasubramaniam 1965). Countries reporting 

 skipjack tuna catches in the Indian Ocean include Australia, Comoros, 

 Indonesia, Japan, Korea, Maldives, Mauritius, Seychelles, and Sri Lanka 

 (Food and Agriculture Organization of the United Nations [FAO] 1979). 



I.B. Trends in Catch and Effort 



Al bacore - The estimated annual catch in the Indian Ocean rose from 

 100 metric tons (mt) in 1952 to 17,700 mt in 1962. From 1962 to 1978, the 

 estimated annual catch fluctuated widely, reaching a high of 28,200 mt in 

 1974 (Table 1 and Figure 2). 



^Weatherall, J. A., F. V. Riggs, and M. Y. Y. Yong. 1979. Some 

 production model analyses of tuna and bill fish stocks in the India 

 Ocean. SWFC Admin. Rep. H-79-7, Nat. Mar. Fish. Serv., NOAA, Honolulu, 

 Hawaii, 12 p. Prepared for the Workshop on the Assessment of Selected 

 Tunas and Billfish Stocks in the Indian and Pacific Oceans, Shimizu, 

 Japan, 13-22 June 1979. 



