Combining surplus production and spectral models to define fishery management advisory - a case study using the threadfinbream fishery along Kerala coast

Threadfinbreams have emerged as a very important resource along the west coast of India both as food fish and as raw material for export oriented surimi production. The state of Kerala contributes 30-40% of the total threadfinbream production in the country landed mainly by multiday trawlers. The analysis of the catch and effort of threadfinbreams during 1985-2012 along Kerala revealed that the landing recently showed decline despite increased fishing effort. A simulation study was conducted to examine the effects of restrictions imposed on the total hours of operation of multiday trawlers on the threadfinbream fishery of Kerala. A genetic algorithm was used for simulation of threadfinbream fishery along Kerala coast using surplus production model and spectral time series methods. Numerical simulations were made for selected seven levels of exploitation and the average biomass and average yield were calculated and compared with the maximum sustainable yield (MSY). The results indicated that the optimum level of exploitation is at 85.1% of the current level of exploitation to keep the average annual yields during 2013-2020 just below MSY