Sexual development in Russian sturgeon (Acipenser gueldenstaedtii) grown in aquaculture
The Russian sturgeon (Acipenser gueldenstaedtii) has been introduced into aquaculture in recent years, following the decline of natural populations and the resultant increases in the price of caviar. In nature, males and females of this species mature sexually after 8 to 13 and 10 to 16 years, respectively. Fertilized Russian sturgeon eggs were bred up to 7 years of age in a commercial farm. Plasma E2 was measured, and developmental stage of the gonads was determined by endoscopy and histology. GnRH, alone or combined with metoclopramide, as well as hCG, were injected into 4-, 5- and 6-year-old females, and E2 levels were determined. Even at 5 years of age, the gonads of all female fish tested were at the pre-vitellogenic stage and they did not respond to exogenous GnRHa or hCG administration. Vitellogenesis started at 6 years of age, when GnRHa treatment elicited a marked increase in E2. However, 3- to 4-year-old males’ testes already contained spermatids and spermatozoa, and they had all matured by the age of 4 years. Ovarian development was highly asynchronous in the early vitellogenic stages. The sexual development of Russian sturgeons bred in captivity was investigated according to morphological, histological and endocrinological parameters. The information on gonadal development in relation to age and body weight is an important management tool for sturgeon aquaculture for reproduction and caviar production.