Indian Ocean Tuna Longline Fisheries

Chinese fisheries catch had increased to 42.7899 millions tons in 2002 after decade's rapid development, many important coastal ocean fishes had been over-exploited to a low catch level in the period. Recent years, the total coastal oceanic catch had decreased slightly, so it had been the basic national policy that we should make arduous efforts to enlarge, optimize, and improve the technological and economic levels of oceanic fishery. Chinese oceanic fishery consisted of coastal trawl fishery in west Africa, oceanic sleeve fish fishery, and oceanic tuna long-line fishery mainly, and the proportion of tuna fishery had increased gradually among them recent years.Oceanic tuna fishery was the old-line fishery industry with large size and production value. Chinese tuna fishery had some problems such as outdated information and production technique, scarcity of technological study, and lower economical benefits, etc. because of short producing period and some other reasons. This paper reported the general situations of tuna fishery in Indian ocean in recent ten years, and studied die fishing efforts, catch, CPUE, and fishing grounds of two long-line crafts from Zhonglu oceanic fishery co. Ltd in equatorial waters of Indian ocean in 2002, in order to gave the new fishery information to the producer, and to improve the technique of our tuna long-line fishery. The results were as follows mainly:The amount of tuna fishing country and ground in Indian Ocean was 40, main countries and grounds were European community, Indonesia, India, Iran, Sri Lanka, Taiwan and Maldives with the catch proportion of 68.17% together in 2000. The tuna fisheries catch was about 1.4 million tons in 2000 with the majority of tunas, especially skipjack, Katsuwonus pelami, yellowfin tuna, thunnus dbacares,and bigeye tuna, thunnus obesus. The main gears were purse, gillnet and long-line in the fishery. China captured small amounts of tunas in Indian Ocean annually, from 444 tons in 1995 to over 6000 tons in 2000.The data from the fishing efforts of the two crafts said, that vessel Taili fished for 250 days in 12 months with the average 20.83 days per month all year; vessel Taikun fished for 200 days in 10 months with the average 16.67 days per month all year. The two vessels fished for 450 days in 2002 with average 37.5 days per month together.The data from the catch of the two vessels indicted that, Vessel Taili captured 190532 kg all year with the average 15878 kg monthly, vessel Taikun captured 181311 kg all year with the average 15109 kg monthly. The two vessels captured 371843 kg together all year and 30987 kg per month averagely.The data from the CPUE of the two vessels said, that the daily catch of vessel Taili was 470-1084 kg monthly with the average 779 kg all year, vessel Taikun had the daily catch of 274-1330 kg monthly with the average 868 kg all year. The daily catch of the two vessels was 472-1240 kg monthly with the peak in February and the bottom in August in 2002. The average daily catch of the two vessels was 810 kg all year.The results from the statistical analysis on experimental data indicted that no prominent differences exited between two crafts on the fishing days, nominal catch and nominal daily catch. The fishing grounds and catch varied markedly monthly.By the paper, the Indian Ocean had about 1.4 millions catch in tuna fishery every year recently, so it was high-catch fishing ground for the tuna fishery. The two vessels had gotten good experimental results about die fishing grounds and technique of the tuna long-line fishery especially in west Indian Ocean, and the experimental results would show important reference for the tuna producer and researcher. And meanwhile, we thought this study was not full-scale and profound still for factors such as few vessels, short experimental time and some other conditions. More study work should be done on the domain in the future.