Abstract
Grey mullet brood stock, maintained under a shifted photoperiod, were treated with controlled- release hormonal devices to accelerate gonadal development and subsequent spawning. The females received testosterone and a superactive GnRH analogue (GnRHa) given via slow-release devices (microspheres). The males received 17ct-methyltestosterone via microspheres. Once oocytes reached the diameter of >500 nm, females were induced to spawn with OtH-calibrated carp pituitary extract followed 24 hours later by GnRHa administered via a sustained-release implant. The females were allowed to spawn in the presence of males. An average of 4.4 million eggs was obtained from each female, and the fertilization rate ranged from 20% to 98%.