Understanding the swimming performance, behaviour and metabolism of the rare juvenile Kaluga sturgeon (Huso dauricus) for its conservation and management.

The Kaluga sturgeon, Huso dauricus, is a rare fish species found in the Heilongjiang River basin of China, primarily within the mainstream of the Heilongjiang River. However, recent years have witnessed the degradation of its wild population due to factors such as overfishing, water pollution and water conservancy construction. To safeguard the genetic diversity of H. dauricus, it is essential to investigate its swimming capabilities, behaviour and metabolic rate during physical activity. This research yields fundamental insights and technical support for fishery enhancement, release strategies, artificial breeding and fishway design. In this study, we assessed critical swimming speed, burst swimming speed and oxygen consumption of H. dauricus. High-speed cameras recorded H. dauricus' swimming behaviour at various speeds, enabling a detailed analysis of tail beat frequency, tail beat amplitude and motion step length (LS). This study contributes crucial baseline data for not only understanding fish behaviour in the Heilongjiang basin but also being a vital technical support for fish stocking initiatives and the design of fish passage facilities in water conservancy projects. These findings hold significant implications for protecting and restoring H. dauricus germplasm resources in the region.