Population characteristics and fishery of yellow fin tuna, Thunnus albacares landed along the Gulf of Mannar coast, Tamil Nadu, India

Abstract

Fishery and population characteristics of yellowfin tuna, Thunrlzis ulbucures were studied. Their annual landings from Gulf of Mannar ecosystem varied between 3 (1991) and 1,006 t (2003). Annual average production for 1989-1995 was 90 t, 1996-2000 was 326 and 2001-'06 was 635. Catch was constituted by relatively small fishes. Population parameters such as growth. mortality and exploitation rates were estimated from length frequency data. Length at first capture was estimated as 52.7 cm, length at first maturity as 71.1 cm and optimum length for exploitation as 96.8 cm. Average standing stock and spawning stock biomass was 675 t and 455 t respectively. Maximum sustainable yield (MSY) was estimated as 690 t. Study revealed that yellow fin resource is subjected to intensive exploitation during 1998-2006. Recruitment pattern indicated that recruitment occurs almost round the year with peak in May-August with 60.5% of the annual recruitment. Food and feeding studies show that they feed mainly on pelagic fishes dominated by carangids, clupeids, beloneids and hemiramphids. Other components in their food are crustaceans and cephalopods.