Early development and allometric growth patterns of Larimichthys crocea (Richardson, 1846)

In order to enhance the hatching rate of eggs and the survival rate of juveniles of Larimichthys crocea (Naozhou population), and provide a theoretical basis for artificial induction and juvenile breeding, this study observed and analyzed the chronological characteristics of embryonic development and larvae(juvenile) development of L. crocea. Morphological parameters were measured, and regression equations for growth characteristics during the juvenile stage were deduced, followed by an analysis of allometric growth. The results revealed that the fertilized eggs of L. crocea were buoyant, with a diameter of (1.27 +/- 0.09) mm, possessing a tough eggshell. The eggs were transparent and spherical, typically containing a single oil droplet without stickiness. Under the conditions of a hatching temperature of (24 +/- 1)degrees C, salinity of (34 +/- 1)parts per thousand, and pH of (7.8 +/- 0.5), embryonic development encompassed 7 stages and 21 periods, requiring 26 h and 1 min. The total length of newly hatched larvae was (2.782 +/- 0.349) mm, showing transparency. They progressed through the larval stage (0-18 DPH) and juvenile stage (19-25 DPH), and by the 25th day, all fins were fully developed. This study recorded the formation time of various organs in L. crocea, and conducted in-depth research on the biological characteristics. The results of allometric growth indicated that a higher allometric growth coefficient (before reaching 6 mm TL) is likely the combined result of various factors in the aquaculture environment, rather than a single factor. Further research should be conducted to investigate which aquaculture environmental factors have the greatest impact on the early development of L. crocea and their regulatory mechanisms. This can provide a theoretical basis for improving the survival rate of its fry.