Demographic Structure and Level of Exploitation of the Small Pelagic Pellonula leonensis Boulenger, 1916 (Pisces; Clupeidae) Fishery in the Aghien lagoon, West Africa

Abstract

Demographic structure and level of exploitation of Pellonula leonensis in the Aghien lagoon were examined by applying length-weight relationship (LWR), Condition factor, Von Bertalanffy model, Mortality parameters, Exploitation rate, Recruitment pattern and Beverton and Holt analysis. Fish population were sampled monthly during one year between June 2014 and May 2015 from artisanal and experimental captures in the Aghien Lagoon. Except LWR and the condition factor, studied parameters were provided by the FiSAT II package. The negative allometric growth (b = 2.61) was reported for Pellonula leonensis. Mean values of the condition factor (CF) vary significantly from one month to another (Anova, p ˂ 0.05). Concerning growth parameters, results indicated that the asymptotic length (L∞) has been estimated at 126.84 mm SL, growth coefficient (K) was 0.67 year ^-1 and growth performance index (Φ') was 2.03. Growth modelization revealed 4 cohorts for Pellonula leonensis. The estimates of the total (Z), natural (M) and fishing (F) mortalities were 1.87, 0.92 and 0.95 year ^-1 respectively. The recruitment pattern was continuous throughout the year with two Gauss curve. The exploitation rate obtained (E = 0.51) was close to E_0.1 (E_0.1 = 0.55), thus indicating that the P. leonensis stock is in an optimum state of exploitation.