Spatial Distribution and Demographic Structure of Pellonula leonensis Boulenger, 1916 (Clupeiforme: Clupeidae) across Fishing Zones of the Taabo Dam Lake, Côte d’Ivoire
Ahoutou Konan Eric *
Faculty of Science and Technology (ST), Alassane Ouattara University (UAO) in Bouaké, BPV Bouaké 01, Côte d'Ivoire and Research Station on Inland Fisheries and Aquaculture, National Agronomic Research Center, 01 BP 633, Bouaké, Côte d’Ivoire.
Anvo Morgane Paul Magouana
Research Station on Inland Fisheries and Aquaculture, National Agronomic Research Center, 01 BP 633, Bouaké, Côte d’Ivoire.
Da Costa Kouassi Sebastino
Research Station on Inland Fisheries and Aquaculture, National Agronomic Research Center, 01 BP 633, Bouaké, Côte d’Ivoire.
*Author to whom correspondence should be addressed.
Abstract
Understanding spatial variation in the demographic structure of exploited fish populations is important for identifying areas where fishing pressure may affect recruitment and reproductive capacity. This study assessed the spatial distribution and demographic structure of Pellonula leonensis across seven fishing zones of the Taabo Dam Lake, Côte d’Ivoire. Commercial fishery landings were sampled monthly from August 2014 to July 2015, and 10,875 specimens were examined for standard length, sex, and maturity stage. Sampling locations and dates were recorded when fishing vessels unloaded their catches, enabling comparison of demographic indicators among the zones. Sex ratios varied significantly among zones, with females predominating at Courandjourou (1:4.63) and Antonio (1:2.01), whereas males predominated at Dike (1.68:1). Mature specimens were more abundant than immature individuals in most zones, although no significant difference was observed in the Islands area. Mature females accounted for 60.71% of catches at Courandjourou, 37.37% at Antonio, 34.48% at Islands, and 31.05% at Port. The proportion of specimens within the optimal size range was highest at Courandjourou (46.07%) and lowest at Dike (23.43%). Super-breeders were poorly represented across all zones, ranging from 2.27% at Antonio to 16.36% at Islands. These findings demonstrate marked spatial variation in sex ratio, maturity composition, and size structure across the reservoir. Continued monitoring incorporating seasonal conditions, environmental variables, and fishing effort is required to confirm these patterns and support the development of zone-specific management measures for the sustainable exploitation of P. leonensis in the Taabo Reservoir.
Keywords: Pellonula leonensis, Taabo Reservoir, demographic structure, spatial distribution, sex ratio, maturity stage, optimal size, super-breeders, inland fisheries, fishery management