Growth, Mortality, Sexual Maturity and Exploitation Level of the Golden African Snapper (Lutjanus fulgens, Lutjanidae) in Ghanaian Waters

Abstract

The golden African snapper, Lutjanus fulgens, is one of the most commercially important demersal species exploited by commercial fishers along the coast of Ghana. Growth and mortality as well as aspects of reproduction of L. fulgens were studied to contribute to the paucity of biological information on the species in Ghanaian waters. Samples were collected along the coast of Ghana from September 2018 to August 2019. Total lengths of L. fulgens sampled ranged between 16.2 and 45.6 cm. Length-weight relationship of the species showed isometric growth pattern. The asymptotic length (L_∞), growth coefficient (K) and age at zero length (t_o) for L. fulgens were estimated as 51.09 cm, 0.47 yr^-1 and -0.301yr respectively. Total (Z), fishing (F) and natural (M) mortality rates of L. fulgens were estimated at 2.69 yr^-1, 1.91 yr^-1 and 0.78 yr^-1 respectively. The length-at-first capture (L_c) = 31.51 cm, was slightly lower than the length-at-first maturity (L_m) = 33.7 cm for females. The exploitation ratio (E = 0.71) of the stocks in Ghanaian waters was above the optimal exploitation levels. Peak spawning period was observed from July to September. Mean fecundity was estimated to be 77,833 ± 13,012 eggs (mean ± SE). There was no significant difference observed in the sex ratio between males and females. The findings suggest the stocks are under high fishing pressure and so it is recommended that to avoid exploiting the spawning biomass, closed season could be observed during the spawning periods.