AQUA_2020_1080: Sperm management of European catfish (Silurus glanis L.) for effective reproduction and genetic conservation

The European catfish (Silurus glanis; also called wels or sheatfish) is one of the largest commercially important freshwater fish species. The objective of this study was to examine the storage time of its semen in an immobilization solution (IS) to enhance conservation and aquaculture programs. Changes in spermatozoan motility was examined in semen stored on ice in 20 mL tubes in IS for 0, 1, 7, 14 and 28 days post-stripping (DPS). Stored sperm samples were pooled and used for fertility testing at 1 and 7 DPS. The IS maintained sperm motility at > 90% during days 1-7 of semen storage, and curvilinear velocity (VCL) and straight-line velocity (VSL) were up to the levels of 163 and 90 mu m s(-1), respectively. Spermatozoa stored for 14 days had 60% motility and VCL and VSL values were similar to those of 7 DPS. Sperm motility was only 1% at 28 DPS with VCL and VSL of 79 and 24 mu m s(-1), respectively. The fertilization and total hatching rates of eggs activated with sperm stored for 7 days were reduced, but the slight decrease was compensated by the increase in supply of spermatozoa which resulted in overall 80% level of fertility and hatching. The number of larval malformations was not correlated with storage time of sperm. Based on the results of this study, sperm from the European catfish can be collected and stored in IS for as long as 1 week, retaining quality sufficient for fertilization to yield normal fry