盐度对云纹石斑鱼(Epinehelus moara ♀)×鞍带石斑鱼(Epinehelus lanceolatus ♂)受精卵孵化的影响及杂交仔稚幼鱼形态发育观察

以云纹石斑鱼(Epinehelus moara)为母本、鞍带石斑鱼(Epineheluslanceolatus)为父本进行种间杂交，观察比较了不同盐度(5、10、15、20、25、30、35、40、45)条件下受精卵的孵化率、初孵仔鱼畸形率，以及仔、稚、幼鱼的生长发育及形态变化；测定了盐度为30时，正常初孵仔鱼的不投饵存活系数(SAI)。结果显示，受精卵孵化的最适盐度范围是35–37，初孵仔鱼最适生存盐度为20–30。盐度为20–35时，仔鱼不投饵存活系数值较高(均在30以上)；盐度为5、10、45时，仔鱼的SAI值较低。胚后发育根据卵黄囊的有无、第2背鳍棘和腹鳍棘的伸长与收缩、鳞片及体色的变化，分为仔、稚、幼鱼3个时期。在本研究条件下，初孵至2日龄为前期仔鱼，初孵仔鱼全长为(1.959±0.152) mm，主要特征为卵黄囊和油球未被吸收消化；3–30日龄为后期仔鱼，3日龄仔鱼全长为(2.765±0.108) mm，主要特征是第2背鳍棘与腹鳍棘的绝对长度已达到仔、稚鱼阶段的最大值；31–45日龄为稚鱼期，31日龄稚鱼全长为(18.130±1.565) mm，主要特征为内脏器官发育完善、鱼体呈透明状；46日龄后进入幼鱼期，此时全长为(39.850±2.565) mm，体色形成、开始被鳞、体表布满细小的棕色斑点。

Effects of Salinity on the Hatching of the Fertilized Eggs ofEpinephelus moara (♀)×Epinephelus lanceolatus (♂) and the Observation of the Morphological Development of Larvae,Juvenile and Young Fish

In this study the hybridization betweenEpinehelus moara(♀) andEpinehelus lanceolatus (♂) were manipulated in the laboratory. The hybrid F1 larvae were hatched at salinity 30. The hatching and deformity rates of fertilized eggs and the survival activity index of newly hatched larvae was observed at salinities 5, 10, 15, 20, 25, 30, 35, 40, and 45. The growth and morphological characteristics of larvae, juveniles, and young fish was recorded. The results suggested that salinity 35–37 was optimum for the hatching of the hybrid F1, and salinity 20 to 30 was optimum for larval survival. SAI values of larvae became higher when the salinity was between 20 and 35, and they were lower when the salinity was 5, 10, and 45. The post embryonic development could be divided into the larval stage, the juvenile stage and the young fish stage, based on the features of the yolk-sac, the second dorsal fin spine, the pelvic fin spine, the scale and the body color. The embryo developed into pre-larvae in 2 days, and the average length of newly-hatched larvae was (1.959±0.152) mm. This stage was featured by yolk-sac and unabsorbed oil ball. The post-larvae stage lasted from Day 3 to Day 30, and the average length of 3-day larvae was (2.765±0.108) mm. At this stage the absolute length of the second dorsal fin spine and pelvic fin spine reached the maximum for larvae and juvenile fish. It entered into the juvenile stage starting from Day 31 after hatching and the average length was (18.130±1.565) mm. At this stage the visceral organs had been fully developed and the fish color became transparent. Starting from Day 46 after hatching it entered into the young fish stage when the average length was (39.850±2.565) mm and the body color turned light brown. At this stage brown spots appeared on the body surface and scales could be observed under microscope.