Growth, Mortality and Exploitation of the African Lesser Threadfin Galeoides decadactylus (Pisces, Polynemidae) Fishing by the Gill Net "Soovi" in Benin Nearshore Waters

The African lesser threadfin, Galeoides decadactylus, is one of the fish species commonly caught in the nearshore waters of Benin. It is well appreciated for the quality of its flesh. But since these twenty past years, the African lesser threadfin's production has been decreasing with more small-sized fishes appearing in catches, and little is known about the species' population dynamics. Therefore, the growth and mortality parameters of the lesser African threadfin offBenin's near shore waters were investigated using length-frequency data of 1027 specimens sampled from Gill net hauls over a period of 12 months. The length-weight relationship was computed from linear regression analysis. Galeoides decadactylus exhibited negative allometric growth (b = 2.955 ≠ 3; p < 0.05) with an abundance of small sized specimens. The von Bertalanffy growth constants for Galeoides decadactylus were TL∞ = 26.25 cm, K = 0.800 yr^sup -1^, and t^sub 0^ = -0.60 yr with a derived growth performance index of [straight phi] =2.741.The instantaneous rates of total mortality (Z), natural mortality (M), and fishing mortality (F) were respectively 1.88, 1.64 and 0.24 per year. The rate of exploitation (E = 0.13) showed an under-fishing of this species. This fishery could be well managed by increasing the fishing effort. Decreasing of the African lesser threadfin population in the catches could be attributed to other factors.