Before the construction of Gezhouba Dam, the spawning ground of the Chinese sturgeon were mainly in the lower reaches of the Jinsha River and upper reaches of the Yangtze River 5.

The Chinese sturgeon is a large anadromous fish, a national first-class protection animal and a critically endangered species 4. However, dams may also change the transport of water and sediment 1, which affects fish habitats as in the case of the required habitats of Chinese sturgeon ( Acipenser sinensis) 2, 3. The dam is intended to provide multiple benefits to society, including power generation and prevention of flooding or droughts. The Gezhouba Dam Project is the first hydropower station on the Yangtze River. We used these results to recommend a new operation scheme to support the conservation of Chinese sturgeon. For discharges above 15,000 m 3/s, all units should be open. A comparison of suitable areas under high-flow showed that at discharges of 12,000–15,000 m 3/s, opening 11–13 units on the left side was optimal.

For discharges below 12,000 m 3/s, most of the area was suitable for discharges above 12,000 m 3/s, the suitable area rapidly decreased with increasing discharge. The suitable-velocity area was maximal when all units of Dajiang Plant of Gezhouba Dam were open. Velocity fields of different opening modes of the generator units were simulated with identical discharge. By inverting the 2016–2019 field monitoring results, the model shows that the preferred velocity range for Chinese sturgeon spawning is 0.6–1.5 m/s. The model was evaluated with velocity measurements, and the results were determined to be in good agreement. To optimize the velocity conditions in the spawning ground by controlling the opening mode of Gezhouba Dam generator units, a mathematical model of Chinese sturgeon spawning ground was established in FLOW-3D. Chinese sturgeon ( Acipenser sinensis) is a critically endangered species, and waters downstream from Gezhouba Dam are the only known spawning ground.

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