Abstract:Investigating the growth conditions of larval and juveniles holds significant importance for understanding fish early life history, population recruitment mechanisms, and fisheries resource management. This study focused on Therapon jarbua, a dominant economical species in the coastal waters of Wenchang, Hainan, utilizing sagittal otolith microstructural analysis to estimate hatching dates and elucidate early growth characteristics. Results demonstrated that all collected specimens (n=119) were in juvenile stage, with body lengths ranging 8.48~14.12 mm, body weights 0.0086~0.0544 g, and daily ages 23~47 days. The hatching period spanned from April 17, 2021 to May 2, 2022, with peak hatching occurring from April to June. Daily mean growth rates of larval individuals from different hatching months were 0.1 mm/day during March-April, 0.19 mm/day in May-June, and 0.24 mm/day in July-August, indicating accelerated growth in later-hatched cohorts. Otolith increment width analysis revealed enhanced growth acceleration after 15 days post-hatching. This research demonstrate the efficacy of otolith microstructure analysis in reconstructing early growth trajectories of Therapon jarbua, providing critical insights into the temporal relationship between hatching chronology and individual growth performance. These findings enhances to understanding population recruitment dynamics through reproductive timing and nursery ground utilization, offering scientific basis for targeted conservation strategies of spawning and nursery cohorts.
