Cryopreservation of kelp grouper (Epinephelus moara) embryos using non-permeating cryoprotectants

Abstract

In this paper, we present a new approach to cryopreserve kelp grouper embryos using non-permeating cryoprotectants (NPC). Various cryopreservation factors (embryo container, cryoprotectant solution, embryonic stage, equilibrium time, solution concentration, and thawing temperature and time) were screened in preliminary experiments. We found that using 1 M sucrose to equilibrate for 5, 6, and 7 mins and using cryotube II as the container for embryos was most effective for the kelp grouper embryos at the 16S and TB stages. Thawing was most effective at 24 °C for 30s. In six of the experiments, at least four groups of embryos survived freezing and thawing. In total, 1195 viable embryos were recovered from those four experiments. The survival rate was 12.60%–31.3%, the hatching rate was 5.08%–41.28%, and maximum alive time of the thawed embryos ranged from 70 h to 9 days. These results are encouraging for future experiments on cryopreservation of kelp grouper embryos using NPCs, and our study provides new cryopreservation conditions for grouper embryos.