Coastal Aquaculture and Mariculture

Unit 3 - Indian Ocean capture fisheries

3.4. High Sea fisheries of Indian Ocean
The high sea of the Indian Ocean support in the long line fisheries carried out for albacore, big eye, blue fin and yellow fin tunas with incidental catches of bill fishes, sharks and so on.
Sashimi grade tunas cost very high in Japanese market and it is costlier than shrimp, the popular export commodity in India and elsewhere. Annual tuna production from Indian Ocean varied around 0.707 to 0.917 million tonnes and India's contribution was 45,000 t which is 5.9% of the total tuna production from Indian Ocean. Thus production in the world continued to increase from an average; annual catch 1.81 million tonnes in 1970s to a peak of 4 million tonnes during early 2000. The contribution towards total tuna production by the Indian Ocean was 21 % which is next to the Pacific Ocean (65%). The production from the Indian Ocean increased from 0.22 mmt to 0.83 mmt during 1970s and 2000 respectively. Though as many as 134 countries produce tuna in the world, only 18 countries contribute more than 1.0% towards the total catch. Among the top twelve tuna producing countries during 1990s five countries such as Philippines (9.7%) Ubdibesua (8.7%) China, Taiwan (6.6%) Thai1and (3.4%) and Maldives (2.0%) contributed about 30% of the total tuna catch.

Tunas are exploited by different types of gears like gillnets, hooks and lines, purse scine, long line, trawl and ring scine. Though many species support the global tuna fishery, only seven species such as Thunnus albacares, T. obesus, T. alalunga, T. thynnus, T. maccoyi, Auxis thazard and Katsuwonus pelamis are universal in occurrence. Among the other species E. affins, T. tonggol, T. atlanticus and Sarda orientalis are found in the Indian Ocean. There is scope for further increase in the production of yellow fin, skipjack and small tunas from the Indian ocean, as the landings of these species continued to increase with minor fluctuations, whereas, Southern bluefin landing started to decline from the early 1980's onward Albacore, bigeye and yellowfin are fully exploited in the Indian ocean and Southern bluefin is on the verge of depletion. Only skipjack is either under or moderately exploited.