Sturgeon population underwent strict threats due to inordinate human activities in the past decade and had been classified into the Red List of Threatened Species in recent years. Stock enhancement is one effective practice for the conservation practice of wild sturgeon. However, the survival condition of sturgeon was not satisfactory after direct re-stocking to natural habitat. Huso dauricus is one important protected sturgeon species and appropriate conservation strategy for wild population is urgent. To clarity the dynamic adaptability of Huso dauricus to wild environment, one thousand individuals were released to natural river. On the 0^th d, 7^th d, 14^th d and 30^th d, five re-captured individuals were used to evaluate the dynamic trends of biochemical biomarkers, intestinal histomorphology, gut microbe taxa composition and transcription profile during 30 d stock enhancement. Our results indicated that Huso dauricus individuals were still in physiological stress status in 7^th d and then gradually adapted to wild habitat after 14 d reintroduction based on the serum cortisol level. Meanwhile, feeding habitat, organ functions indicators and growth performance also showed similar dynamic changes within 30 d. Interestingly, gut bacteria diversity and taxa structure also fluctuated during 30 d re-stocking, which accompanied with the dynamic changes in intestinal pathological injury and tight junction protein expression in this period. Transcriptome revealed that dynamic adaptability of Huso dauricus to wild habitat associated with the expression mode of FoxO family, immune, cytochrome family and ATP metabolism-related genes. Taken together, the present research demonstrated that artificial reintroduction possessed dynamic impacts on the health condition of Huso dauricus and 14 d wilderness training might be essential for sturgeon re-stocking practice. Our study reveal the adaption mechanism of Huso dauricus during re-stocking period from molecular level and shed light on the theoretical guideline for wild sturgeon conservation.
 

Stock enhancement; Sturgeon; Environment adaption; Huso dauricus; Conservation biology