1Department of Fisheries, Faculty of Natural Resources, University of Guilan, Sowmeh Sara, Iran
2Fisheries General Directory of Guilan, Bandar Anzali, Iran
3Shahid Dr. Beheshti Sturgeon Fish Propagation and Rearing Complex, Rasht, Iran
Since sturgeons have no external sexual dimorphism and there are no external markers to determine sex, internal examination of the gonads should be used to sex identification. The present study describes the biopsy method and histological observations of the gonads of great sturgeon (Huso huso) in both sexes at different age classes. Sex and maturity stages of 226 great sturgeons were identified through gonadal biopsy and histological observations. A 20-25 mm incision was made with a sharp scalpel through the ventral midline between pectoral and pelvic fins, that allowed gonads to be viewed. Determination of sex and maturity stage was successfully performed in all fish. The sex ratio under culture conditions was 1:0.84 (female: male). Most males and females were at mid-spermatogenesis and pre-vitellogenesis stages, respectively. No apparent mortality and infection was observed after surgery and gonad biopsy in fish. Results of this study showed that sex could be identified by this method when fish are 3-year-old or more. Therefore, biopsy technique is a simple and cost-effective tool in sturgeons and has an important role in aquaculture management and conservation benefits.