野生和养殖曼氏无针乌贼亲体形态、生化组分及其胚胎发育的比较

为优化曼氏无针乌贼人工繁育技术，提高人工增殖苗种的产量与质量，采用实验生态学方法，对比分析了野生和养殖曼氏无针乌贼（Sepiella japonica）的表观形态、生化组分及其受精卵的形态差异，探究了光照周期与受精卵胶质外膜对曼氏无针乌贼胚胎发育的影响。结果显示：野生和养殖曼氏无针乌贼的表观形态、生化组分均存在显著差异，野生群体性成熟规格远大于养殖群体，肌肉和肝脏组织中的脂肪含量显著低于养殖群体（P<0.05），卵巢中的蛋白质含量则显著高于养殖群体（P<0.05）；养殖亲体所产黑卵在12D12L光照周期条件下孵化率最高，所产白卵在24D和24L条件下孵化率最高，野生亲体所产卵在24D和12D12L条件下孵化率最高；随光照时间的延长，受精卵的平均孵化时间具有先增加后减小的趋势，表明光照周期是影响曼氏无针乌贼胚胎发育的重要因素；实验发现，将受精卵胶质外膜剥离处理后，养殖亲体所产黑白卵的平均孵化时间具有减少的趋势，但孵化率显著下降（P<0.05）。综上所述，建议在曼氏无针乌贼人工苗种生产过程中，尽量选用大规格野生乌贼作为繁育亲体。此外，在受精卵孵化期间，应对孵化池进行适当遮光处理，避免受精卵长时间暴露于强光照环境中，以提高孵化率和仔乌成活率。本实验研究结果可为曼氏无针乌贼人工苗种繁育技术优化提供参考。

Comparison between the wild and hatchery-reared Sepiella japonica in morphology, biochemical composition and embryonic development

Hatchery-reared aquatic organisms usually have morphologically and physiological differences compared to their wild conspecifics, which may have negative consequences for the production of the juveniles under hatchery rearing conditions. To optimize the artificial breeding technologies of Sepiella japonica, we compared the morphology, biochemical composition and embryonic development between wild and hatchery-reared Sepiella japonica. Furthermore, we also explored the effect of light cycle and capsule layer peeling on the embryonic development of Sepiella japonica. The results showed that there were significant differences in morphological characteristics and biochemical components between wild and hatchery-reared Sepiella japonica. The body sizes at maturity were much bigger in wild Sepiella japonica compared to their hatchery-reared conspecifics. The lipid contents in muscle and liver of wild Sepiella japonica were significantly lower than that of hatchery-reared (P<0.05). The protein contents in the ovary of wild Sepiella japonica were significantly higher than that of hatchery-reared (P<0.05). The hatching rate of the black eggs spawned by the hatchery-reared cuttlefish was the highest when eggs exposed to a 12:12-hours light: dark cycle. The hatching rate of the white eggs spawned by the hatchery-reared cuttlefish was the highest when eggs exposed to the 24 hours dark cycle and 24 hours light cycle. The hatching rate of the black eggs spawned by the wild cuttlefish was the highest when eggs exposed to the 24 hours dark cycle and 12: 12-hours light: dark cycle. With the increasing light duration, the hatching period of fertilized eggs showed a tendency that first increased and then decreased, which indicated that light cycle was an important factor for the development of embryonic. With egg capsule layer peeling, the fertilized eggs from hatchery-reared Sepiella japonica showed a significant decreased hatching rate (P<0.05), and the hatching time showed a decreasing tendency. To improve the hatching rate of the fertilized eggs and the survival rate of new hatchling, it is important to add sufficient number of wild brood-stock into productive group during artificial breeding and seedling production programs. Moreover, low light intensity should be implemented during the incubation of the fertilized eggs, which may improve the rate of the fertilized eggs and the survival rate of new hatchling. This study could provide useful information for the optimization of artificial breeding technological of Sepiella japonica.