Video credit: Ahmed Shaheen (Egypt)
Review: Ahmed Shaheen and Abdel Rahman El Gamal (Founder of the video channel)
This video was filmed in the first constructed governmental marine hatchery located in Alexandria (Egypt).
Since the grey mullet cannot reach its full sexual maturation in captivity, the broodstock that are required for the artificial reproduction has to be obtained from the wild.
As the video starts with the catching of broodstock then stocking and maintain them in outdoor tanks until moving the ready-to-spawn broodstock into the indoor facility in the hatchery. The video shows the egg sampling process using a catheter.
In this particular process, females are hormonally induced while males can be only checked based on releasing sperm upon a light pressure. If males are not ready, hormonal induction is administered. In order for a successful reproduction, egg diameter has to reach 500 microns.
The hormone used in case of females is done as follows:
First injection: Human Chorionic Gonadotropin (HCG) at the dose of 10,000 IU/kg of the female size
Second injection: LHRH at the dose of 10-20 microgram/kg of the female size
In regard to unready males, the injection is done under skin using 17-alpha methyl testosterone at a dose of 10 microgram/male size (about 300-350 g/specimen). This is done 3 weeks before the spawning period.
The broodstock are stocked the spawning fiberglass tank of about 4 to 4.5 m3 size at a rate of three males to one female. Once the spawning is observed, the broodstock are lifted from the spawning tank leaving the fertilized eggs to develop. In a tank as such, about 250,000 – 500,000 embryos are produced bearing in mind the high fecundity of the species which is about 1.5 million eggs/kg of a female weight. Hatching occurs after about 100 to 110 hours at 25 C.
Note: the technology of the artificial reproduction of grey mullet is available in Egypt but it is carried out only at experimental scale. Fish farms rely on naturally collected mullet fry which is always larger in size and at much lower cost compared to hatchery-produced seeds. The scaling up of the artificial reproduction of mullet would be only justified upon the stopping of the collection practice of the mullet fry from the wild.