Fishery and biology of tunas in the Indian seas

Abstract

Tunas and tuna-like fishes belong to 6 genera, viz., Thunnus, Katsuwonus, Euthynnus, Auxis (tribe Thunnini) and Sarda (bonitos) and Gymnosarda (tribe Sardini) of the family Scombridae. Tunas are among the largest, most specialized and commercially important of all fishes (Collette and Nauen, 1983). They are found in temperate and tropical oceans around the world and account for a major proportion of the world fishery products. Tunas are unique among fishes because they possess body temperature several degrees higher than the ambient waters and have high metabolic rates that enable them to exhibit extraordinary growth patterns. They have streamlined bodies and vary extensively in size, color and fin length. They are fast swimmers capable of traveling more than 48 km/h (Collette and Nauen, 1983), migratory and have few predators. They are the second most important item, next only to shrimps, in the world seafood trade and therefore form specifically targeted fisheries globally by nations such as France, Spain, Thailand, Taiwan, Korea, Japan and USA. In the Indian Ocean which contributes 19% of the world tuna catch, tuna fishing and fisheries have emerged as focal points to address issues of sustainable development and management of fishery resources, especially in the context of EEZ regulations, UNCLOS and other international conventions.