On the Population Dynamics of Labeo senegalensis (Valenciennes, 1842) in Upper Atbara and Settit Dam Complex, Eastern Sudan

Abstract

In the present study, 500 specimens of Labeo senegalensis were collected from artisanal fishing boats during the period from September 2019 to January 2020. The total length of the collected specimens ranged from 21.2 to 47.5 cm with a mean of 27.7 ± 10.91 cm. The maximum length was 45.0 cm, while the maximum predicted length at the 95% confidence limit was 46.18 cm. The length-weight relationship was highly correlated (r = 0.947), with a b-value of 2.847, indicating negative allometric growth. Growth parameters estimated from the von Bertalanffy growth model were: L∞ = 47. 5 cm, K = 0.86 yr⁻¹, and theoretical age at zero length “t0” was -0.786 yr⁻¹. The relative longevity (Tmax), was 2.7 years; and the growth performance index at 3.28. The total, natural, and fishing mortality rates were estimated as 2.29 yr⁻¹, 1.38 yr⁻¹, and 0.91 yr⁻¹, respectively, which gives an annual exploitation rate of 0.4 yr⁻¹. The exploitation levels at 10%, 50%, and maximum sustainable exploitation (Emax) were calculated as 0.355, 0.278, and 0.421, respectively. The capture lengths at 25%, 50%, and 75% were estimated as 16.56 cm, 20.39 cm, and 24.14 cm, respectively. Maximum, limit, and optimum fishing levels of fishing (Fmax, Flimit, and Fopt) were found to be 0.81, 0.92, and 0.55, respectively. The asymptotic length of L. senegalensis population “L∞ “in this study was calculated at 30 cm, while the growth coefficient “K” was found to be 1.5 yr⁻¹. The length of catch at 50% and 75% was estimated at 9.5 and 12 cm, respectively. This investigation was important for monitoring and managing fisheries resources to enhance sustainability and conservation efforts of the stocks of L senegalensis, one of the most important commercial fish species in the Upper Atbara and Settit Dam Complex.