Development of an extender solution for short-term sperm storage to promote seed production in alfonsino Beryx splendens

The alfonsino Beryx splendens is an important fishery resources in Japan but recently its catch has declined dramatically. To promote seed production of this fish species, we developed an extender solution for short-term storage of sperm. We diluted the semen in several solutions with different concentrations of salt, Ca2+, pH, etc. and examined the motility after storage in a refrigerator (4–5℃) for days or weeks. Slightly hypotonic NaCl solution with low concentrations of KCl and CaCl2 at pH 7.5 efficiently maintained the viability of sperm with high percentages of motility. The addition of both glucose and glycine prolonged the storage period for sperm. By using the extender solution developed in this study, we kept the alfonsino sperm active for up to 81 days in a refrigerator with the swimming velocity of 69.0 µm/s and motility of 11.2%. The alfonsino sperm stored in this extender solution for 24 days retained fertilizing capacity.