Population dynamics and biological parameters of the Nile perch (Lates niloticus, Linnaeus, 1758) in Roseires Reservoir, Sudan

Abstract

This study examined key biological characteristics and population dynamics of the commercially important Nile perch (Lates niloticus) in the Roseries Reservoir, Sudan. A total of 654 specimens were collected tri-monthly from four reservoir stations between April 2019 and March 2020 using experimental multi-filament gill nets. Total and standard lengths were measured to the nearest millimeter, ranging in total length from 9 to 85 cm, with a mean length of 40.35 ± 13.43 cm. Analysis of the length–weight relationship indicated negative allometric growth (b = 2.652). Age composition ranged from 1+ to 6+ years, with an estimated maximum longevity (Tmax) of 8.37 years. Growth parameters derived from the von Bertalanffy growth model revealed an asymptotic length (L∞) of 93.54 cm and a growth coefficient (K) of 0.34 yr⁻¹. Mortality estimates showed a total mortality rate (Z) of 1.13 yr⁻¹, with natural mortality (M) of 0.63 yr⁻¹ and fishing mortality (F) of 0.5 yr⁻¹. The exploitation rate (E) was 0.44, indicating that the stock is being harvested at an optimal level. These findings provide critical baseline information for stock assessment and support the development of sustainable fisheries management strategies for Nile perch in the Roseries Reservoir