Abstract:According to the tuna catch database established by Indian Ocean Tuna Commission (IOTC), which covers the time from 1967 to 2004, the annual and the total catch in each spatial grid of 5°×5° were summarized. In addition, the maps of total catch distribution of the Indian Ocean tuna long-line fishing were plotted using GIS software, and the spatial distribution of tuna were analyzed. The analysis showed that big eye tuna Thunnus obesus, yellow fin tuna T.albacares, albacore T.alalunga and swordfish Xiphias gladius were the main species caught by tuna longline fisheries in the Indian Ocean, which comprised 90% of the total catch weight. Although the catch weight of the four main species in the Indian Ocean showed a trend of increase from 1967 to 2004, the maximum and minimum productions were different. Though the four species distributed widely in the Indian Ocean, their top catch areas were widely different.
