Research on artificial breeding and cultivation technology of Decapterus maruadsi

Objective This study aims to investigate the artificial breeding and aquaculture techniques of Decapterus maruadsi.

Methods Through intensive cultivation of wild broodstock of D. maruadsi, 200 broodfish were used for artificial induced natural spawning, and a comparative feeding trial (the iced trash fish group and the formulated feed group) for adult fish rearing was conducted in offshore raft cages.

Results The results showed that: 1) In Zhangzhou, Fujian, the gonads of D. maruadsi started to develop in March, expanded rapidly in April, reached the maximum gonadosomatic index in May, and degenerated to a relatively low level in June. The breeding season lasted from late April to late May, with one reproductive cycle per year. When cultivated with diets such as Uroteuthis chinensis and Perinereis nuntia, the gonads of 1-year-old female and male fish could develop to stage Ⅳ, but they couldn’t spawn or ejaculate voluntarily. Artificial spawning induction via injection of human chorionic gonadotropin (hCG) and luteinizing hormone-releasing hormone analog (LRH-A₃) could induce the release of physiologically mature sperms and eggs, which then completed natural fertilization in water. During sexual maturation rearing, the body mass growth rate of D. maruadsi fed with iced trash fish was significantly lower than that of the formulated feed group (P<0.05), while the gonad weight of the iced trash fish group was significantly higher than that of the formulated feed group (P<0.05), indicating that feeding iced trash fish could promote gonadal development, increase the gonadosomatic index of D. maruadsi, and facilitate subsequent artificial breeding operations. 2) Approximately 450 000 fertilized eggs were obtained, and about 220 000 larvae were hatched, with a hatching rate of 58%. 3) One month after hatching, the larvae could reach a body length of (1.3±0.2) cm; on the 65th day post-hatching, the body length of D. maruadsi exceeds 5 cm. 4) The offshore raft cage feeding comparison revealed that the formulated feed group had slightly higher growth rate and survival rate than the iced trash fish group, proving that formulated feeds were suitable for D. maruadsi during the adult rearing stage.

Conclusion The phased breakthrough in artificial breeding and aquaculture techniques of D. maruadsi can preliminarily solve the seedling source problem of this species, and provide technical references for its high-value development and utilization.