Reproductive biology of Synodontis membranaceus in the Bagoué River (Ivory Coast)

This study aims to describe the reproductive parameters of Synodontis membranaceus in the Bagoué River basin. Sampling campaigns were carried out every two months from August 2018 to February 2020. The Synodontis membranaceus individuals used for the reproduction study were obtained from experimental and commercial fishing. The size at first sexual maturity (L50) for females and males is 110.49 mm and 93.65 mm (standard length), respectively. The average gonadosomatic index (GSI) of Synodontis membranaceus females shows two periods: the first from October 2018 to April 2019 and the second from April 2019 to October 2019, with high GSI values (0.14% and 0.39%). In addition, the percentage of mature females during this period is greater than 50%. The gonads therefore reach maturity between February and August. The spawning period takes place from August to February. The estimated absolute fertility of Synodontis membranaceus ranges from 2,451 to 15,411 oocytes with an average of 7,157 ± 3,810, and relative fertility is 121 oocytes to 2,342 oocytes per gram of body weight. The average relative fertility is 574 ± 472 oocytes per gram of body weight. In conclusion, the study of reproduction reveals that males reach sexual maturity before females.