FISHERIES RESEARCH INSTITUTE,MOA,TAIWAN

The objective of this study was to investigate the effects of salinity onsurvival, developmental, and hatching rate of the embryo before and postorganogenesis (gastrula, pre-hatching stage) of the grouper Epinephelus coioidescultured in different salinity of saltwater. Salinity treatments were carriedout by transferring fertilized egg from the base salinity seawater (35 ppt) intoa beaker containing water with test salinity 5~45 ppt. The results indicatedthat salinity level 5 and 45 ppt were beyond the limits for normal embryonicdevelopment. The total hatching rate, dead egg rate and un-hatch egg rate weresignificantly affected by salinity 5 ppt between gastrula and pre-hatchingstage. The hatch rates of pre-hatching stage were 3 times larger than gastrula,but dead egg rates of post organogenesis were 20 times less than beforeorganogenesis at 5 ppt of salinity. The just hatching egg rate had no differencebetween before and post organogenesis, and their values were 16~20 % at 5 pptsalinity. The un-hatch embryo rates of pre-hatching stage were higher thangastrula at 5, 20 ppt of salinity. Gastrula embryos (before organogenesis) ofthis study are generally considered to be the more sensitive stages to salinitytreatment than those pre-hatching stage in embryonic development.