Early efforts

Established in 1982, the institute, an affiliate of China Three Gorges Corp, is tasked with monitoring the level of biodiversity in the waters near the dam, the world's largest hydropower facility.

The sturgeon-releasing event, held in the lead-up to the International Day for Biological Diversity on May 22, was part of a broader and long-running effort by authorities to repair the ecology of the Yangtze. Strained by factors such as overfishing, pollution and the environmental consequences of dams and hydropower plants, the wild sturgeon population has shrunk to dangerously low levels, prompting artificial breeding efforts and the rise of release events.

The fish population in the river — and the fishery harvests — fell in the early years of the People's Republic of China, which was founded in 1949. The construction of dams and hydropower infrastructures, such as the Three Gorges Dam, on the Yangtze is one of a number of factors contributing to the decline. The human structures altered the river's flow, reduced connectivity and raised concerns among the nation's scientific community about the well-being of the species, experts said.

Wei Qiwei, an aquatic product researcher at the Chinese Academy of Fishery Sciences in Beijing, said that an estimated 10,000 Chinese sturgeons lived in the Yangtze in the 1960s. The population fell to just over 2,000 in the 1980s, then just 50 in 2005.

"There are only about a dozen wild Chinese sturgeons living in the Yangtze at present," he said in an interview with China National Radio in March last year.

Jiang, the chief engineer, said that in the 1960s, concerns were mainly focused on the well-being of four species that were critical to local fishing industry.