The Effect of Seasonality on the Diet and Biochemical Composition of the Stomach Contents Tilapia Sarotherodon melanotheron melanotheron (Rüppell, 1852) in three Aquatic Ecosystems of Côte d'Ivoire (Sector VI of Ebrié lagoon, Ayamé Lake 1 and Aby-Nord lagoon)

Abstract

Culture of Sarotherodon melanotheron presents major difficulty, which is the valorization of artificial food by this species. Thus, this study aims to identify preferential prey of this species in three aquatic ecosystems (sector VI of Ebrié lagoon, Ayamé Lake 1 and Aby-Nord lagoon), with a view to developing natural food resources in farming environments. The sampling was carried out from March 2017 to February 2018 using 80 to 100 mm gillnets. Stomachs of 343 specimens were analyzed by microscopic observation, preys were identified, feed index (AI) was calculated and nutritional quality of food bolus has been determined. IA shows a preference of specimens from sector VI for Coscinodiscus sp. at dry season (IA=58.63%), rainy season (IA=65.97%) and flood season (IA=21.06%). Coscinodiscus sp. remains an essential prey in Aby lagoon at high rainy season (IA=45.66%), a dominant prey at small dry season (IA=76.06%) and small rainy season (IA=92.29%). On the other hand, in Ayamé Lake 1, Aulacoseira sp. is important prey (IA =19.03%) in high dry season, essential prey (IA=48.19%) at high rainy season and dominant prey (IA=61.21%) at small dry season. At alimentary bolus, highest contents of proteins (22.44%) and lipids (2.36%) were obtained at high dry season in the Aby lagoon. The contents of hydrolysable organic matter (4499.50 to 781.3 mg.g-1) and minerals (161.3 to 406.2 mg.g-1) remain high in three aquatic ecosystem regardless of the season. In conclusion, species has a preference for genera Coscinodiscus sp. and Aulacoseira sp and quality of food bolus is superior in lagoon.