Effect of hormone implantation on cryopreservation of Atlantic halibut (Hippoglossus hippoglossus L.) sperm

Hormone implantation is widely applied in halibut (Hippoglossus hippoglossus L.) aquaculture to extend the sperm production season of broodstock males. The ability to combine this technique with cryopreservation would increase sperm availability, thereby improving reproduction success and facilitating gene management. In this paper, the cryopreservation ability of sperm from hormone-treated males was examined at three times post-implantation and compared with that of sperm from males that were not hormone-treated. All sperm samples were cryopreserved using the same method. The effectiveness of these techniques was assessed by examining the fertilization rate and motility of thawed sperm. The spermotocrit and concentration of fresh sperm samples were measured to reveal the effect of hormone implantation on sperm characteristics. The reported results indicate that hormone implantation did not affect cryopreservation efficiency. The fertilization rate resulting from thawed sperm of hormone-treated males showed no significant difference from that of untreated males or from fresh sperm. A significant positive relationship was demonstrated between the spermatocrit and concentration of sperm; and a significant decrease of spermatocrit was found in sperm collected from hormone-treated males 14 days post-implantation. No significant linear relationship between spermotocrit and fertilization rate of thawed sperm was shown.