Population Dynamic of the Shield-head Catfish Synodontis Schall (Bloch & Schneider, 1801) in Upper Atbara and Setit Dam Complex, Sudan

Abstract

This study aimed to assess important population bio-parameters of Synodontis schall in the Upper Atbara and the Setit dam complex (Sudan), comprising asymptotic length, growth curvature, length at maturity, optimum length, growth performance index, and mortality rate. The study was based on the need to assess capture fisheries; whose success depends on understanding the species' population structure. For five months (September 2019 and January 2020), 500 specimens of S. schall were collected randomly using gillnet from fishermen monthly. Morphometric parameters were taken in the field. The length-weight relationship demonstrated a strong correlation coefficient of r = 0.902, indicating a negative allometric growth pattern with a b-value of 2.619. The von Bertalanffy growth function was used in estimating population parameters obtained from length-frequency data; The asymptotic length (L∞) was 36.75 cm, the growth curvature (K) was 0.78 yr.-1, and the optimum length (Lopt) was 23.09 cm. The total mortality (Z) was 2.09 yr.-1; exploitation rate (E) = 0.34 yr. -1, natural mortality (M) and fishing mortality (F) = 1.39 and 0.7 yr. -1, respectively. The overall growth performance index of 3.023 indicated a slow rate of growth. The results suggest that this species and other commercial species require further research on population dynamics.