Anticipating the Effects of Increasing Rivers’ Water Salinity for Sustainable Conservation of Tilapia Resources in Rural Coastal Zone of Benin, West Africa

Abstract

The current research aimed at using the application of multi-factor models to support fisheries management decisions for successful resources’ conservation. The study was based on the tilapia species Coptodon guineensis, which is among the most widely exploited in Benin coastal zone. In an attempt to suggest conservation strategies, the phenotypic variability of 356 accessions of this species was assessed in relation with water salinity, and several interactions. The fish were collected through small-scale experimental fishing using cast nets and gillnets. The findings indicated that the salinity observed in the sampled rivers is due, at proportions ranging from 0.13% to 47%, to the sea surface salinity (SSS) of the Atlantic Ocean, suggesting a leading inland origin of the salinity of these rivers. The evidence also showed that the tilapia populations have been relatively adapted to the increasing water salinity of the sampled rivers. The fish species*river type and fish species*fish sex interactions had significant effects on phenotypic characteristics rather than river type*fish sex interaction. For an efficient conservation of these populations, two conservation areas (Lake Nokoué and Porto-Novo lagoon vs Lake Toho and Grand-Popo lagoon), could be considered for this tilapia species.

Keywords: Aquatic salinization, population adaptation, growth parameters, interaction patterns