Effect of long-term storage on the quality of cryopreserved sperm of the giant grouper, Epinephelus lanceolatus

The giant grouper, Epinephelus lanceolatus, is one of the most valuable tropical commercial fishes. The asynchronous maturity periods between males and females hampers breeding programs. Sperm cryopreservation for gamete conservation is important for fish reproduction. We evaluated the effects of storage for 1, 3, 4, and 5 years on cryopreserved sperm of the giant grouper, E. lanceolatus, in 10% DMSO as a cryoprotectant with artificial seminal plasma and 300 mM sucrose as a diluent. Sperm motility, cell survival rate, DNA damage, fertilization rate, and hatching rate were investigated in this study. Post-thaw sperm motility peaked after 1 year of storage (63.27 +/- 2.87%; p < 0.05), followed by 3 and 4 years (54.50 +/- 4.33% and 54.40 +/- 0.30%, respectively). Post-thaw sperm motility decreased after 5 years of storage. The cell survival rate after 1 year of storage (91.54 +/- 3.02%) was similar to that of fresh sperm (98.12 +/- 0.44%). The rate of DNA damage was unaffected by storage but significantly higher than that of fresh sperm. The fertility rate was significantly higher after storage for 1 and 3 years (98.06 +/- 0.57% and 93.26 +/- 1.73%, respectively). Samples stored for 1 and 3 years also resulted in high hatching rates (95.90 +/- 1.53% and 88.73 +/- 1.15%, respectively), which tended to decrease with increasing storage duration. Sperm cryopreserved for 4 years were of good quality in terms of motility and cell survival rate. However, storage for longer than 3 years decreased the fertility and hatching rates.

Automated summary

This study evaluated the effects of long-term storage on cryopreserved sperm of the giant grouper and found that 1-year storage resulted in the highest post-thaw sperm motility. The cell survival rate after 1 year was similar to fresh sperm, but the rate of DNA damage was higher. Fertility and hatching rates were higher after 1 and 3 years of storage, but decreased with longer storage duration.