Abstract:Yellowtail amberjack, Seriola quinqueradiata, is a globally distributed, economically important, marine pelagic fish species belonging to the same genus as S. aureovittata and S. dumerili. It is a popular table fish worldwide because of its flavorsome flesh and high nutritional value. Recently, we made a breakthrough in triggering the natural spawning of S. quinqueradiata by manipulating photothermal regimes in China, and produced over 7700 juveniles with an average total length (TL) of 147 mm in an indoor tank culture system. Meanwhile, the morphological and quantitative characteristics and the growth and development of S. quinqueradiata during the early life history stages were observed and described for the first time. The mature eggs of S. quinqueradiata are transparent, spherical, and buoyant, with a single oil globe with a diameter of approximately 1.26~1.36 mm. The embryos hatched out at approximately 37 h 40 min post hatching at a water temperature of (22.0±0.5)℃. The embryonic development process can be divided into eight stages: pre-cleavage, cleavage, blastula, gastrula, neurula, organogenesis, muscle effect, and hatching. The morphology of embryonic development has been described previously. The TL of the newly hatched larvae was (4.03±0.27) mm with an oval yolk sac, which accounted for 3/8 of the TL. The TL of larvae 3 days after hatching (DAH) was (16.23±1.61) mm, and the mouth opened and larvae entered the mixed nutrition period. The first food was a rotifer. The TL of larvae at 6 DAH was (4.93±0.17) mm; here, the yolk sac was exhausted and the swim bladder started to inflate. The TL of larvae at 10 DAH was (5.21±0.23) mm, and the larvae entered the exogenous nutrition stage. The TL of larvae at 15 DAH was (6.24±0.66) mm, and the end of the spine began to bend. The TL of larvae at 25 DAH was (10.25±1.35) mm, and the spine bending process was completed; thereafter, the larvae began to feed on Artemia nauplii. The TL of juveniles at 30 DAH was (16.23±1.61) mm, which is when commercial feed conversion started, and the juveniles began to feed well on the commercial diet at 40 DAH when the TL reached (28.07±2.32) mm. The TL of juveniles at 65 DAH was (81.49±5.11) mm, which was when the juvenile morphology was similar to the adults. Furthermore, the suitable temperature for embryonic development was determined to be 22℃~24℃. The results provide technical support regarding artificial breeding and seedling production technology of S. quinqueradiata that could boost the development of the S. quinqueradiata farming industry in China.
