The Chinese sturgeon (Acipenser sinensis), a critically endangered flagship species of the Yangtze River, faces severe reproductive failure due to habitat fragmentation and dam-induced flow regulation. This study investigates the spawning habitat selection strategies and suitability of Chinese sturgeon under semi-natural controlled conditions. In a side channel at Yanziba (Yichang, China), captive-bred broodstock were released into a flow-regulated reach designed to mimic natural hydrodynamic and substrate features. A multi-sensor acoustic monitoring system – including DIDSON imaging sonar, M1200d acoustic camera, Simrad EY60 echosounder, and a Vemco Positioning System (VPS) – was deployed to record three-dimensional movement trajectories and spawning behavior. Simultaneously, hydrodynamic simulations and field measurements characterized flow velocity, depth, temperature, and substrate distribution. Preliminary results indicate that the sturgeon exhibit a clear preference for 3–5 m deep gravel-bed areas with moderate flow (0.6–1.0 m/s) during the spawning period. Behavioral data and habitat models suggest that flow regulation can significantly influence microhabitat suitability and spawning success. The study provides an experimental framework linking fish behavior, hydraulic environment, and reproductive outcomes. Findings will support ecological flow design and habitat restoration strategies for Chinese sturgeon recovery in the Yangtze River.

Chinese sturgeon; spawning behavior; hydrodynamic modeling; habitat suitability; Yangtze River conservation；