棕点石斑鱼(♀)×鞍带石斑鱼(♂)杂交子代胚胎及仔稚幼鱼发育的跟踪观察

Embryonic and Morphological Development in the Larva, Juvenile, and Young Stages of Epinephelus fuscoguttatus(♀)×E. lanceolatus(♂)

本研究阐述了棕点石斑鱼(♀)×鞍带石斑鱼(♂)杂交子代(简称珍珠龙胆石斑鱼)的胚胎发育和仔稚幼鱼形态发育的特征及其养殖过程中的一些难点、要点,以期为今后苗种的规模化培育生产提供参考依据。通过对珍珠龙胆石斑鱼各个发育期连续取样,系统观察并记录各发育期的形态变化及生长特征。结果表明,1)在水温27-28℃条件下,历时25 h 25 min孵化出膜,整个发育过程划分为卵裂期、囊胚期、原肠胚期、神经胚期和器官形成期。2)在水温(27.0±0.5)℃、盐度30、p H 8的培育条件下,根据卵黄囊、第二背鳍棘和腹鳍棘的生长与伸缩及鳞片、体色的变化将胚后发育分为仔鱼、稚鱼、幼鱼3个时期。仔鱼期根据卵黄囊的有无分为前期仔鱼和后期仔鱼。初孵至孵化后4 d为前期仔鱼;孵化后5 d,仔鱼卵黄囊完全消失,成为后期仔鱼;孵化后32 d,50%的仔鱼进入稚鱼期;孵化后46 d,50%的稚鱼完成变态,成为幼鱼。初孵仔鱼的全长平均为(1.65±0.11)mm,发育至70 d时,幼鱼平均全长已达(75.47±0.19)mm。跟踪观察的结果发现,珍珠龙胆石斑鱼作为杂交子代,从受精到发育的各阶段均能健康正常地生长发育,且生长快速、抗病力强,具有"虎斑头、龙胆尾"的外型,具有明显的杂交优势。

The current study investigated the Epinephelus fuscoguttatus（♀） × E. lanceolatus（♂） hybrid embryo and larvae in the terms of the morphological characteristics to provide a basis for the future breeding. The results show that embryonic development required 25 h 25 min at 27-28℃. The embryonic developmental process included five stages：cleavage stage, blastula stage, gastrula stage, nerve stage, and organogenesis stage. The post-embryonic development included larval, juvenile, and young fish stages at （27±0.5）℃, salinity 30, and pH 8 based on the features of the yolk sac, second dorsal fin spine, pelvic fin spine, scales, and body color. Larval was further divided into early and late larval larvae according to the presence or absence of yolk sac. Newly-hatched to 4-day was the early larvae, and larvae hatching yolk sac completely disappeared at 5 d. Fifty percent of larvae entered larval period at 32 d. Fifty percent larval completed the metamorphosis that developed into juvenile fish. The average total length of newly-hatched larvae was （1.65±0.11） mm, reaching （75.47±0.19） mm at 70 d. These results indicated that the hybrid offspring from conception to the later stages are healthy and normally-grown and developed; the disease-resistant heterosis had the appearance of“Epinephelus fuscoguttatus head and E. lanceolatus tail”.