Backgroud The sea cucumber Apostichopus japonicus is one of the most economically valuable sea cucumber species in China. Among the various regions, Fujian Province stands out as the most significant production area for A. japonicus in southern China, ranking the third nationwide in terms of output. However, large-scale artificial breeding of A. japonicus in southern regions remains underdeveloped.
Objective To address this gap, the study aims to explore the feasibility of autumn seedling breeding of A. japonicus in southern China.
Methods This investigation employed low-temperature induction and feed enhancement techniques to promote gonadal maturation from May to October. Spawning and hatching occurred in October, and the study analyzed the early developmental characteristics and growth of the larvae.
Results The study demonstrated that the combination of low-temperature induction and feed enhancement techniques significantly promoted gonadal development, resulting in successful sexual maturity during the autumn period. The fertilized eggs obtained through a method known as dry-flow stimulation exhibited distinct characteristics: they were spherical, transparent, and demersal, with an average diameter of (151.5±1.5) µm. This size and transparency are crucial indicators of healthy fertilization and potential viability in larval development. Under conditions of water temperature 21.5−22.5 °C, salinity 29−30, and pH 7.8−8.3, normal embryonic and post-embryonic development were observed. The developmental stages included several key phases: fertilized egg, cleavage, blastula, gastrula, auricularia, doliolaria, pentactula, and juvenile. In total, this process encompassed 18 periods across 8 distinct stages, illustrating a comprehensive growth trajectory from fertilization to juvenile stages. The study recorded impressive developmental rates, with the hatching rate of auricularia larvae reaching 75.00%. Additionally, the occurrence rate of doliolaria larvae was an impressive 84.40%±4.85%, and the attachment and metamorphosis rate was recorded at 82.37%±2.83%. These figures indicated a robust and healthy development process, highlighting the effectiveness of the breeding techniques employed. From fertilized eggs to juveniles, the developmental timeline spanned 16 days. Initially, the juveniles appeared transparent white, indicating their early developmental stage. Remarkably, after 30 days, their coloration transitioned to darker shades, with green or reddish-brown hues becoming prominent by the 60-day mark. At this stage, the juveniles achieved an average body length of (30.00±1.37) mm, underscoring their healthy growth trajectory.
Conclusion In conclusion, the findings of this study indicate that under controlled conditions, large-scale autumn breeding of A. japonicus seedlings is indeed feasible in southern China. Furthermore, after 60 days, the juveniles exhibited a growth advantage compared to those bred in northern regions, suggesting that the southern climate may be particularly conducive to the growth of A. japonicus. This research not only provides a foundational basis for the autumn seedling breeding of A. japonicus in China, but also opens avenues for further exploration in sustainable aquaculture practices. By enhancing breeding techniques and improving larval survival rates, it’s possible to boost the production of this economically valuable species, contributing to the livelihoods of many in the aquaculture industry.
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