Impact of dredging on the ichthyofauna of the lowlands: comparison of the reproduction parameters of Sarotherodon melanotheron populations (Rüppell, 1852) of dredged lowlands and the coastal lagoon at togbin in southern Benin

Abstract

The sampling between June and September yielded 428 specimens (230 for lagoon and 198 for shallows) on which breeding parameters were determined; monitoring monthly measurements of the physicochemical parameters of the water. In the long run, only the depth differs between the two environments (Prof lag = 1.57 m, Prof bottom = 6.2 m) (p <0.05). The absolute fertility obtained in the lagoon (1,552 eggs) did not differ from that of the lowlands (1,468 eggs) (p> 0.05). The sex ratios obtained are not different from the unit (lagoon p = 0.99204, lowlands p = 0.7113). The first sexual maturity sizes of females and males are respectively 6.51 cm and 7.17 cm for the lagoon and 15.32 cm and 10.65 cm for the dredged bottomlands. The ovarian diameter revealed the size of the eggs in the shallows (0.17 cm) compared to the lagoon (0.11 cm). Ultimately, dredged water bodies will only serve biodiversity.