Effect of aromatable androgen (17-methyltestosterone) on induced maturation of silver European eels (Anguilla Anguilla ): Oocyte performance and synchronization

The reproductive performances of silver European eel in term of gonad development and egg production, employing slow-release implants with the androgen 17-MT (1mg) in combination with traditional weekly injection of carp pituitary extract (CPE) was evaluated. Wild female European eels (Anguilla anguilla) underwent a standard induction protocol with CPE and were randomly divided into three groups (N-group, no implant; Y-group, with implant; and control, C-group, no treatment). The results showed that 17-MT-treated females (Y-group) reproduced spontaneously about 6 weeks earlier than the N-group females with a saving of almost 40% in CPE and time of induction. Concerning artificial induction of maturation in female silver eels, our study demonstrated that they positively respond to androgen exposure also in terms of eggs productivity. Indeed, Y-group was more productive than N-group: in Y-group, 11 eels ensured an eggs production that exceeded 50% of initial body weight (BW), whereas in N-group only three eels have exceeded this value. The results suggest that 17-MT should be considered in future protocols for the improvement of the artificial reproduction of female silver European eels.