Spawning season variations of female Nile Tilapia, Oreochromis niloticus, from man-made lakes of Cote D'Ivoire

The spawning season of Oreochromis niloticus females was studied over two a nnual cycles in 6 small agropastoral and 2 large hydroelectric reservoirs o f Cote d'Ivoire (Ayame and Kossou), situated between 5 and 10 degrees N of latitude. Reproduction occurred during a marked season in the agropastoral reservoirs and in Lake Ayame, whereas it was continuous in Lake Kossou. Spa wning season differed between reservoirs and among years within the same re servoir. Seasonal changes in temperature, rainfall, day length, chlorophyll a concentration and water level often corresponded with changes in the ann ual spawning cycle. However, annual periodicity of O. niloticus reproductio n was more likely influenced by the ephemerides cycle.