Heavy landings of yellowfin tuna Thunnus albacares (Bonnaterre, 1788)by hooks and line off Chennai coast

Tunas are commercially important fish and widely but sparsely distributed throughout the oceans of the world, generally in tropical and temperate waters. They are grouped taxonomically in the family Scombridae, which includes about 50 species. The most important of these in commercial and recreational fisheries are yellowfin (Thunnus albacares) (Fig. 1), skipjack (Katsuwonus pelamis), bluefin tuna (T. tonggol), frigate tuna (Auxis thazard) mackerel tuna (Euthynnus affinis) and striped bonito (T. orientalis). They are exploited mainly by hooks and line, mechanised gillnets and trawlnets in India.