Effects of Salinity, Water Temperature and Development Stage on the Hatching Rate and Survival of Fertilized Eggs in Hybrid Grouper (Epinephelus fuscoguttatus ♀ × E. lanceolatus ♂) for Long-distance Transport

Abstract

: We examined the effect of salinity and water temperature on hatching and survival rates of fertilized eggs of hybrid grouper ( Epinephelus fuscoguttatus ♀ × E . lanceolatus ♂ ) at different developmental stages, determining optimal conditions for their long-distance transportation. Deformities and hatching rates of fertilized grouper eggs were observed at salinities of 24, 27, 30, 33, 36, and 39 psu. The optimal salinity was determined to be 36 psu, with a survival rate of 70.0 ± 2.0%. Transportation experiments at 36 psu were conducted at water temperatures of 21, 24, 27, and 30 o C, different developmental stages such as morula, 5-myomere, and tail beating for hatching and survival rates. The optimal water temperature and developmental stage for transporatation were 30 o C and tail beating stage and those hatching rates were 50.6 ± 1.9% and 86.3 ± 1.3%, respectively. At 21 o C, the survival rate by transportation water temperature was highest (73.1 ± 10.6%), but the hatching rate (17.1 ± 3.1%) was lowest. Therefore, the hybrid grouper fertilized eggs ( E. fuscoguttatus ♀ × E . lanceolatus ♂ ) can be most efficiently produced under long-distance transportation conditions during the tail beating stage and at a water temperature of 30 o C.