鞍带石斑鱼(♀)×蓝身大斑石斑鱼(♂)杂交F1代变态发育和生长特征分析

Analysis of metamorphosis development and growth characteristics of hybrid offspring of Epinephelus lanceolatus ♀× Epinephelus. tukula ♂

为了深入研究鞍带石斑鱼(Epinephelus lanceolatus)(♀)×蓝身大斑石斑鱼(E.tukula)(♂)杂交F1代的变态发育及生长特征,本研究对杂交组和纯种鞍带石斑鱼胚胎发育时间、受精率、畸形率、孵化率和仔稚幼鱼生长性状(全长、体长、体高、肛前距),以及杂交组卵黄囊和油球吸收过程,第二背鳍棘和腹鳍棘生长和收缩,口径和眼裂的变化等进行了详细的观察描述和统计分析。结果显示,在水温28℃条件下,杂交组和鞍带石斑鱼受精卵分别经21h24min和21h32min完成胚胎发育;杂交F1代受精率、畸形率和孵化率分别是89.09%±0.08%、35.16%±5.05%和62.59%±10.70%,与纯种鞍带石斑鱼无显著性差异。根据卵黄囊、第二背鳍棘、腹鳍棘、鳞片、体色等形态变化,将其胚后变态发育分为前期仔鱼(孵化后0~6d)、后期仔鱼(孵化后7~34d)、稚鱼期(孵化后35~46d)和幼鱼期(孵化后47~86d),前期仔鱼生长较缓慢,后期仔鱼到幼鱼期生长逐渐加快,86d时杂交组和对照组体长分别达(60.80±0.50)mm和(51.80±0.47)mm,杂交组生长速度极显著高于对照组(P<0.01)。在胚胎发育时期卵黄囊消耗量为29.45%,油球消耗量为20.75%,卵黄囊在孵化后1d消耗最快,达58.70%。油球在孵化后3d消耗最快,达32.08%,孵化后第5d仔鱼卵黄囊和油球基本吸收完毕。第二背鳍棘、腹鳍棘在孵化后29d达到最长,分别是(8.15±0.02)mm和(5.80±0.10)mm,至47d完全退化,变态发育完成。第一天仔鱼眼径为(0.16±0.01)mm,至86d眼径增大22倍,第四天口裂长为(0.09±0.02)mm,至86d增大99倍。结果表明,鞍带石斑鱼(♀)×蓝身大斑石斑鱼(♂)杂交F1代胚胎和仔稚幼鱼发育正常,而且杂交F1代与母本相比具有较显著的生长优势,本研究为两种石斑鱼杂交苗种培育、发育研究和品种改良提供了丰富的数据。

In order to further study the metamorphosis development and growth characteristics of the hybrid offspring of Epinephelus lanceolatus♀×E. tukula♂, we measured embryonic development time, fertilization rate, deformity rate, hatching rate and growth traits (full length, body length, height and anal front) of the hybrid offspring and E. lanceolatus. We also observed the absorption process of yolk sac and oil globule, the growth and contraction of the second dorsal spine and pelvic fin spine, and the changes of eye diameter and oral fissure during embryonic development of hybrid offspring. Statistical analysis of the data was performed. The results show that the hybrid offspring and E. lanceolatus complete embryo development at 21 h 24 min and 21 h 32 min at 28℃, respectively;the fertilization rate, deformity rate and hatching rate of hybrid offspring are 89.09%±0.08%, 35.16%±5.05% and 62.59%±10.70%, respectively, no significant difference is shown compared with that of E. lanceolatus. According to the morphological changes of yolk sac, second dorsal spine, pelvic fin spine, scales and body color, the post-embryonic metamorphosis is divided into early larvae (0–6 d after hatching), late larvae (7–34 d after hatching), juveniles (35–46 d after hatching) and juvenile fish period (47–86 d after hatching). The growth of the early larvae is slower, while the growth of the larvae to the juveniles increases gradually. At 86 d after hatching, the body lengths of the hybrid offspring and E. lanceolatus reach (60.80±0.50) cm and (51.80±0.47) cm, which indicates the growth of the hybrid offspring is significantly faster than E. lanceolatus (P<0.01). During embryo development, the yolk sac consumption is 29.45%, the oil ball consumption is 20.75%, and the yolk sac consumption is the fastest at 1 d after hatching, reaching 58.70%. The oil globule consumption is the fastest at 3 d after hatching, reaching 32.08%, and the yolk sac and oil globule of the larvae are basically absorbed at 5 d after hatching. The lengths of the second dorsal spine and pelvic fin spine reach the longest of (8.15±0.02) mm and (5.80±0.10) mm at 29 d after hatching respectively, and they completely degenerate at 47 d after hatching which marks the completion of metamorphosis.The eye diameter of the larvae is (0.16±0.01) mm at 1 d after hatching, which increases by 22 times at 86 d after hatching. The length of oral fissure is (0.09±0.02) mm, and it increases by 99 times at 86 d after hatching. The results show that the hybrid offspring of E. lanceolatus♀×E. tukula♂ develops normally, and the hybrid offspring shows a significant growth advantage comparing with its female parent. This study provides rich data for seed cultivation, development research and variety improvement of the hybrid offspring.