Population Biology and Reproductive Characteristics of Pseudotolithus elongatus in the Cacine River Estuary, Guinea-Bissau

Résumé fourni par la source

Pseudotolithus elongatus is one of the most commercially important species supporting artisanal fisheries in Guinea-Bissau; however, its population biology and reproductive characteristics remain poorly understood, particularly in estuarine ecosystems. This study provides the first integrated biological characterisation of P. elongatus in the Cacine River Estuary, Guinea-Bissau, based on 1776 specimens collected through three independent sampling programmes. Length at first sexual maturity (L50) was estimated using binomial generalised linear models (GLMs); length–weight relationships were assessed by ordinary least squares regression and analysis of covariance (ANCOVA); sexual size dimorphism was evaluated using a battery of parametric and non-parametric tests (ANOVA, Welch’s t-test, Kruskal–Wallis, Kolmogorov–Smirnov); and sex ratio was tested using chi-square goodness-of-fit tests with Yates’ continuity correction. Females attained sexual maturity at a significantly smaller size than males (L50 = 224.9 mm vs. 306.8 mm), and both sexes exhibited positive allometric growth. Females attained larger body sizes and predominated in the largest length classes, confirming pronounced sexual size dimorphism. Reproductive activity occurred throughout the year, with a distinct spawning peak during the dry season (February–April), and the overall sex ratio remained close to parity despite significant variation among length classes and months. These findings provide a biological baseline to support evidence-informed fishery management of P. elongatus in Guinea-Bissau and highlight the need for long-term, standardised monitoring in the Cacine River Estuary.