Successful hybridization of groupers (Epinephelus coioides x Epinephelus lanceolatus) using cryopreserved sperm

This study examined the effect of three extenders, Marine Fish Ringer (MFR), sodium citrate (CT), and sodium chloride (NaCl) and two cryoprotectants (10% dimethyl sulfoxide-DMSO and 15% Trehalose) on the cryopreservation of giant grouper, Epinephelus lanceolatus sperm which was later used for hybridization trial with orange-spotted grouper, Epinephelus coioides. Fish Ringer and sodium citrate as extenders resulted in higher fertilization (71 ± 3 and 68 ± 4%, respectively) than NaCl (58 ± 1%). There was no difference in percent fertilization and hatch between DMSO and Trehalose and all combinations of extenders and cryoprotectants tested. Successful hybridization of E. coioides x E. lanceolatus was achieved for the first time between these two species using cryopreserved sperm from giant grouper. There was no difference in percent fertilization and hatch between hybrid and nonhybrid, orange-spotted grouper, but percent deformity of the hybrids (47%) was higher (P< 0.05) than non-hybrid (21%). Survival (22%) of the hybrid was lower than non-hybrid (51%) 12. days post hatching (first feeding period). However, this difference was not significant at the end of 45-day study period. Development stages were also not different between hybrids and non-hybrids during the observation period, except hybrid grouper exhibited yellow color with 5-7 oblique black bars across their lateral lines, similar to that of giant grouper by day 45 post hatching. This study successfully demonstrated the use of cryopreserved sperm from giant grouper to produce E. coioides x E. lanceolatus hybrid offsprings thus, laying the groundwork for further comparative studies on hybrid performance.