Channel catfish ovarian fluid differentially enhances blue catfish sperm performance

Area of Science:

• Reproductive Biology
• Aquaculture
• Fish Gamete Interactions

Background:

• Ovarian fluid (OF) plays a critical role in externally fertilizing fish by influencing sperm performance and fertility.
• Understanding gamete interactions is essential for channel catfish (Ictalurus punctatus) ♀ × blue catfish (Ictalurus furcatus) ♂ hybrid aquaculture success.
• Sperm performance is significantly impacted by the female's ovarian fluid environment.

Purpose of the Study:

• To determine the impact of channel catfish OF on blue catfish sperm activation and performance.
• To assess variations in sperm behavior when activated in OF from individual female catfish.
• To evaluate the influence of specific male-female gamete interactions on fertilization outcomes.

Main Methods:

• Sperm from four male blue catfish were activated with and without diluted OF from six individual female channel catfish.
• Sperm motility, velocity (VCL), and longevity were quantified using computer-assisted sperm analysis (CASA).
• A total of 24 experimental crosses were analyzed to assess sperm performance metrics.

Main Results:

• Ovarian fluid significantly increased sperm velocity at 10, 20, and 30 seconds post-activation compared to the control.
• Sperm motility was significantly higher in OF at 30 seconds post-activation, with no significant difference at 10 or 20 seconds.
• Ovarian fluid treatments substantially enhanced sperm longevity, and significant male × female interactions affected all measured sperm parameters.

Conclusions:

• Ovarian fluid is crucial for simulating natural conditions and accurately assessing fish sperm performance in vitro.
• Specific male-female gamete interactions are highly significant and influence sperm motility, velocity, and longevity.
• Further research into gamete interaction mechanisms can improve in-vitro fertilization protocols and aid conservation efforts for threatened freshwater species.