PRODUCTION OF HYBRID GROUPER Epinephelus lanceolatus ? × Epinephelus fuscoguttatus ? USING CRYOPRESERVED SEMEN TRANSPORTED BY DRY ICE
Hybrid groupers are popular cultured fish for the Asian marine finfish aquaculture industry. The shortage of E. lanceolatus semen is a constraint for the production of hybrid grouper fry. Cryopreserved semen were transported by packaging in a Styrofoam box with dry ice as preservation medium. Transportation of cryopreserved semen from the cryopreservation centre to production hatcheries was by commercial courier service provider. The performance of cryopreserved semen transported using dry ice was tested in artificial insemination of hybrid grouper based on the fertilization rate, hatching rate and abnormalities of the produced larvae. Five treatments were employed in the experiment: exposure of the cryopreserved semen inside a sealed Styrofoam box loaded with dry ice for 24 hours (Treatment 1), 48 hours (Treatment 3) and, 72 hours (Treatment 5) and immersion of the cryopreserved semen into liquid nitrogen after exposure to dry ice for 24 hours (Treatment 2) and 48 hours (Treatment 4). The two controls were fresh semen (negative control) and cryopreserved semen in liquid nitrogen (positive control). There was no significant difference (P > 0.05) on the fertilization rate for all controls and treatments. For hatching rate, there was no significant difference (P > 0.05) among two controls and Treatment 1 and Treatment 2. There was also no significant difference (P > 0.05) among the positive control, treatment 1, treatment 2 and treatment 3. There was significant difference among treatment 1, treatment 3 and treatment 5. Hatching rate of Treatment 4 was significantly lower compared to other treatments except to Treatment 5. There was no significant difference (P > 0.05) in the larval abnormalities among the controls and treatments. The conclusion of the study was clear that transported cryopreserved semen can be used effectively in artificial insemination of hybrid grouper.