Effect of slow-release 17β-estradiol injection on the growth performance of female Siberian sturgeon, Acipenser baerii (Brandt 1869) broodstock at different sexual maturity stages

Introduction: Sturgeon aquaculture is of great economic importance due to the high value of caviar and meat. However, challenges such as reproductive and growth limitations in female broodstock hinder productivity in controlled environments. Steroid hormones are among the key factors regulating growth and reproduction in fish. Among them, 17β-estradiol (E₂) plays a crucial role in sexual differentiation, gonadal development, and metabolic regulation. Slow-release hormone delivery methods have been proposed as a potential approach to enhance growth and maturation in fish species. The aim of the present study was to investigate the effect of slow-release E₂ injection on the growth performance of female Siberian sturgeon, Acipenser baerii at different sexual maturity stages.
Materials and Methods: A total of 30 female Siberian sturgeon were selected and categorized into three groups based on their sexual maturity stage (II, III, and IV). Each stage was divided into two subgroups: 1) E₂-treated group (received 2 mg E₂/kg body weight); 2) Control group (received 0.2 mL coconut oil/kg body weight). The hormone was administered intraperitoneally every two months, and the experiment lasted four months. Biometric measurements and growth performance, including body weight, total length, weight gain (WG), specific growth rate (SGR), body weight increase (BWI), condition factor (CF) and average daily growth (ADG) were conducted at 30-day intervals. Statistical analysis was performed using repeated measures analysis of variance to assess the effects of treatment, maturity stage, and time on growth indices.
Results and Discussion: The findings revealed a significant interaction (P<0.05) between treatment, sexual maturity stage, and time in all growth parameters except CF. The highest final body weight (7950 ± 320.93 g) and total length (120.60 ± 11.20 cm) were recorded in the E₂-treated fish at stage IV after 120 days, while the lowest body weight (4170 ± 137.47 g) and total length (94.50 ± 0.93 cm) were observed in control fish at stage II after 30 days (P<0.05). The highest WG (610 ± 18.70 g), SGR (0.42 ± 0.00 %/day), BWI (13.62 ± 2.33 %), and ADG (20.33 ± 3.30 g/day) were recorded in the E₂-treated fish at stage II after 90 days (P<0.05). The CF remained unchanged across all groups, and no mortality was observed throughout the experiment. These findings indicate that E₂ administration promotes somatic growth at early maturity stages (II), whereas at advanced stages (IV), it facilitates gonadal development. The hormonal influence on growth appears to be stage-dependent, with higher energy allocation towards reproductive tissues at later stages. Similar studies on other sturgeon species (e.g., Huso huso, and Acipenser stellatus) suggest that E₂ stimulates insulin-like growth factor-I production and enhances protein synthesis, ultimately improving growth. However, excessive doses may negatively impact somatic growth by favoring gonadal tissue development.
Conclusion: Slow-release E₂ injection significantly affects the growth performance of female Siberian sturgeon, with stage-dependent effects. At early maturity stages (II), it stimulates somatic growth, while at advanced maturity stages (IV), it promotes reproductive development. These findings suggest that timing and dosage optimization are crucial for maximizing the benefits of hormonal treatments in sturgeon aquaculture. Further research is needed to explore the molecular mechanisms underlying E₂'s role in growth regulation and to determine the long-term reproductive consequences of hormone administration.