Fishery and stock structure of Thunnus albacares (Bonnaterre, 1788) off Andhra waters along western Bay of Bengal

The fishery and stock structure of Thunnus albacares off Andhra waters along western Bay of Bengal was studied from 2012 to 2015. The average annual landing of the species during the study period was 5,952 t contributing 32.9 % of the total tuna landings. Gill nets contributed 59 % of the catches, followed by hook and lines (34 %). Von Bertalanffy growth equation was L-t = 196.35 [1 - e(-0.23 (t+0.0546))] and natural mortality, fishing mortality and total mortality was 0.4, 0.71 and 1.11 with exploitation ratio of 0.64 and exploitation rate of 0.43. Annual average stock, standing stock biomass and maximum sustainable yield were 13,879 t, 8,383 t and 4,653 t, respectively. Yield per recruit and biomass per recruit estimated were 2584.7 g and 3640.4 g. The exploitation rate, yield and yield per recruit indicate the stock of T. albacares to be overexploited. To sustainably and optimally harvest the species, reduction in the present fishing effort by 60 % is necessary, thereby increasing the yield by 35.31 %. With overcapacity in the number of gillnetters and hook and line units operating in the waters off Andhra Pradesh, implementation of the recommended fleet size proposed by Central Marine Fisheries Research Institute by means of buy-back measures and strict adherence to Minimum Legal Size at harvest would ensure sustainable and optimum exploitation of the resource.