Thai Tuna Longline Fishing in the Indian Ocean from 2000 to 2006

Abstract

               Thai tuna longliners were operating in the Indian Ocean from 2000 to 2006; data from their logbooks displayed important information of their fishing operation. Total annual catches during the period were: 384.90, 390.93, 93.57, 252.48, 272.41, 280.12 and 414.44 tonnes, with a value of 2, 1.84, 0.46, 1.16, 1.58, 0.98 and 2.42 million USD, respectively. Fishing grounds were in four zones namely: the Bay of Bengal, the west coast of Indonesia, Somalia and the Seychelles, and the southern part of the Indian Ocean.

                The highest catch rate was found in Somalia and the Seychelles (1.3 fish/100 hooks), followed by the west coast of Indonesia (1.2 fish/100 hooks) and the southern part of the Indian Ocean (1.0 fish/ 100 hooks). The lowest catch rate was reported in the Bay of Bengal (0.7 fish/100 hooks), which compared to other fishing grounds. The major catch species were bigeye tuna (Thunnus obesus), yellowfin tuna (T. albacares), albacore tuna (T. alalunga), and swordfish and other large pelagic species comprising 36.64, 35.77, 20.28 and 7.31% of the total seven-year catch, respectively. Bigeye tuna were caught in all fishing grounds, with the highest catch in the southern part of the Indian Ocean. Yellowfin tuna occurred in all fishing grounds. However, the highest abundance was found in Somalia and the Seychelles, while the lowest numbers were found in the Bay of Bengal. Albacore tuna were dominant in the southern part of the Indian Ocean. Other large pelagic species recorded included: swordfish (Xiphias gladius), sharks, blue marlin (Makaira mazara), black marlin (M. indica), striped marlin (Tetrapturus audax) and sailfish (Istiophorus spp). Thai tuna longliners fished north of equator during 2000 to 2002 and moved south of the equator during 2003 to 2006. Analysis of catch data by the PRIMER program showed changes in target species from yellowfin tuna, bigeye tuna, swordfish and other species during 2000 to 2002 to albacore tuna, bigeye tuna, yellowfin tuna, swordfish and other species during 2003 to 2006.