Study of the population structure, exploitation level and growth in relation to the otoliths weight of Pseudotolithus senegalensis (Valenciennes, 1833) and Pseudotolithus typus (Bleeker, 1863) in Benin coasts

Abstract

Abstract Pseudotolithus senegalensis and Pseudotolithus typus are two species of Scianidae family, with commercial importance that can be found in the offing of Benin coasts. The population structure, exploitation level and growth in relation to the otoliths weight of these two species were assessed from 154 and 159 specimens of P. senegalensis and P. typus respectively sampled from fishermen of the Artisanal Fishing Port of Cotonou for four (04) months period. The study of population structure of these two species showed dominance of males with single-modal height distribution for P. senegalensis and bimodal for P. typus. The curve of length-weight relationship indicates positive allometric growth for P. senegalensis (b = 3.360; p < 0.05) and P. typus (b = 3.317; p < 0.05). Growth parameters and performance index ϕ' estimated for both species are L ∞ = 37.80 cm, K = 1.100 an − 1, ϕ'= 3.196 for P. senegalensis and P. typus, L ∞ = 53.55 cm, K = 0.480 an − 1 and ϕ'= 3.139. The exploitation level shows an under exploitation of their stocks. Besides, the otoliths weight relation with fish length showed that b < 3 and positive correlation was observed between otoliths weight and fish weight for both species.