Tuna resources exploratory fishing survey by tuna longline in the Eastern Indian Ocean
1991
Chitjaroon Tantivala (Oceanic Fisheries Div., Bangkok (Thailand))
Tuna resources exploratory survey by tuna longline in the Eastern Indian Ocean covered 14,000 square nautical miles, the total catch of 12,169.6 kilograms was obtained by tuna longline 69,949 hook, the hooking rate was 8.93 no./1,000 hooks. Tunas are dominant species which consists of 52.16 % of the total, the hooking rate was 4.64 no./1,000 hooks. The fishing ground which yielded a comparatively high hooking rate was at the Ninety East Ridge where the average hooking rates of dominant species were Yellowfin tuna 3.04 no./1,000 hooks, Bigeye tuna 0.89 no./1,000 hooks and Skipjack 1.33 no./1,000 hooks. The period from April-May had a higher hooking rate than the period from February-March. In addition, it was found that during the former period the highest hooking rate was at the depth around 123-128 meters with temperature of 15.9 deg C whilst in the latter it was at 140-145 meters depth and temperature 17.2 deg C. The species compositions consisted of 14 family, 20 genus and 30 species.
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