Fishery and length based population parameters of little tuna, Euthynnus affinis (Cantor, 1849) from Gulf of Mannar, Southwestern Bay of Bengal

摘要

Little tuna is the third major tuna species landed along Tuticorin coast after Yellow fin and Skipjack tuna. The species is mostly harvested by large meshed drift gillnets where minor and seasonal catches comes from trawls and lines. Few months post fishing ban period are peak fishing season with high catch rates. There does exist, a seasonal shift in fishing ground in response to changing wind and current pattern. The species showed a positive allometric growth with 'b' estimated as 3.1989. Asymptotic length (L-infinity) and growth coefficient (K) were 79.0 cm and 0.63 yr(-1), respectively. The natural, fishing and total mortality were calculated as 1.03 yr(-1), 1.37 yr(-1) and 2.40 yr(-1), respectively. The current exploitation ratio of 0.57 is considerably lower than Emax indicating the possibility of enhancing the production from the capture fisheries.