Stock assessment of the bigeye grunt Brachydeuterus auritus (Valenciennes, 1832) in the coastal water of Ivory Coast.

Abstract

The stock assessment of Brachydeuterus auritus was carried out in the coastal water of Ivory Coast from January to December 2009. Monthly length frequency data were analyzed using FiSAT software and Jones’ Cohort Analysis Model for the estimation of population parameters, total biomass and Maximum Sustainable Yield (MSY). The asymptotic length (L∞) was 25.20 cm, the growth coefficient (K) was 0.58 year-1, and the calculated growth performance index (φ’) was 2.57. The total mortality (Z), the fishing mortality (F) and the natural mortality (M) were 2.01, 0.74 and 1.27 year-1, respectively. The exploitation level (E) was 0.37 while the maximum allowable limit of exploitation (Emax) was 0.85. The biomass was 2507 tons, which provided the MSY of 2079 tons. The recruitment pattern was continuous with two major peaks per year. The exploitation level (E = 0.37) and the fishing mortality approximated the precautionary target reference point (0.64 year−1) and was within the precautionary limit reference point (0.84 year−1), suggesting that the big eye grunt stock is exploited at a low rate.