NANJING -- In the city of Nanjing, East China's Jiangsu province, 300 captive-bred Chinese sturgeon, along with other rare fish, were released into the longest river in the country.

It marked the first time the first-class state-protected animal had been released in the Nanjing section of the Yangtze River. Some 4,000 mullets, a species under second-class state protection, were released at the same time.

The released sturgeon, which were raised through artificial breeding, are generally 15 months old and measure between 50 cm to 80 cm. Each of these sturgeon is implanted with a harmless transponder to track their whereabouts in the event they are unintentionally caught.

Nicknamed "aquatic pandas," Chinese sturgeon have existed for more than 140 million years. However, the population of the species in the Yangtze plummeted in the late 20th century due to intrusive human activities.

Releasing artificially bred sturgeon is conducive to the reproduction and recovery of the species' wild population in the Yangtze River, said Liao Xiaolin, a researcher with the Institute of Hydroecology, which is jointly administered by the Ministry of Water Resources and the Chinese Academy of Sciences.

After a 10-year fishing ban took effect in the pivotal waters of the Yangtze River in 2021, the population of rare aquatic creatures in the river has increased.

For example, a scientific investigation conducted by the Ministry of Agriculture and Rural Affairs in 2022 showed that the number of Yangtze finless porpoises had exceeded 1,200, up 23.42 percent from five years ago.