Reproductive characteristics of wild population of Sebastiscus marmoratus in Daya Bay

In order to strengthen the resource conservation and artificial propagation of Sebastiscus marmoratus in Daya Bay, we combined morphometric analysis, histology and microscopy to analyze the population structure, gonadal development and reproductive habits of the wild population. The results show that: 1) The sex ratios of S. marmoratus populations sampled in winter and spring were 1.5∶1 and 2∶1, respectively. The body mass of male individuals in spring was significantly greater than that in winter (p<0.05), while there was no significant difference in the body mass between female individuals in spring and winter (p>0.05). 2) The condition factor, viscera-somatic index, and gonadosomatic index of female individuals in winter were significantly greater than those of male individuals (p<0.05), and the gonadosomatic index of female individuals in spring was significantly greater than that of male individuals (p<0.05). Moreover, the gonadosomatic index of female individuals in winter was significantly greater than that in spring (p<0.05). 3) The body mass of both female and male individuals was significantly correlated with morphological traits such as total length, body length, and body height (p<0.05). In addition, the body mass of female individuals was significantly correlated with tail handle length (p<0.05). 4) The absolute fecundity of female individuals (40−50 g) was about 5 192−11 027 eggs. The average long axis of fertilized eggs was 716.58 μm, the head-to-tail length of larvae in the ovary could reach 2.07 mm, and the total length of newly hatched larvae was approximately 2.80−4.50 mm. The osmotic pressure of ovarian cavity fluid during larval incubation was 496 mOsm·L⁻¹. The results indicate that the spawning season of S. marmoratus in Daya Bay is November–April, which provides key biological parameters for its conservation of wild resources and large-scale artificial breeding.