The effects of different hormonal treatments on the oocyte maturation in wild grey mullet (Mugil cephalus) collected from the Iranian coastal waters of the Oman Sea

To investigate the effects of different hormonal treatments on the oocyte maturation in wild- caught grey mullet (Mugil cephalus), fish were subjected to 4 different hormonal treatments as follows: (a) a control group received 0.5 ml/kg B.W. physiological saline, (b) fish injected with 20 mg/kg carp pituitary extract (CPE) as a priming dose followed by 200 µg/kg sGnRHa as resolving dose, (c) fish injected with 200 µg/kg sGnRHa as a priming dose followed by the same injection as a resolving dose and, (d) fish received 20 mg/kg CPE as a priming dose followed by injection of 200 µg/kg sGnRHa in Freund’s incomplete adjuvant emulsion. All GnRHa treated groups received 20 mg/kg B.W. metoclopramide as dopamine antagonist (DA). The interval between two injections was 24 hrs. At 6, 12, 24 and 48 hours post final injection ovarian sles were taken by soft plastic catheter and the maturation of oocytes was examined according to oocyte diameter, position of germinal vesicle and coalescence of oil droplets. The results showed that all hormonal treatments were significantly effective in progression of the oocyte maturation in comparison to control group. The treatments (b) and (d) were more effective than treatment (c) and resulted in final oocyte maturation and germinal break down. It was for the first time that emulsified GnRHa (sGnRHa-FIA) was shown to be effective in final oocyte maturation and ovulation of the species. The results showed that all hormonal treatments were effective in induction of oocyte maturation in wild-caught grey mullet and could be used in commercial hatcheries.