'Extinct' Yangtze sturgeon making a comeback

Du was the project leader, and Zhou Liang, head of the Yibin institute, participated in the whole process.

"The 20 Yangtze sturgeon that were involved in the experiment came from my institute," Zhou said.

Many researchers have said that without the Zhou family, the Yangtze sturgeon might have become truly extinct, both in the wild and in captivity.

In 1993, Zhou's father Zhou Shiwu, a fan of aquatic fauna, founded the institute — the country's first private organization for the protection of rare fish. In 1998, the institute successfully bred Yangtze sturgeon, and six years later it started breeding the species on a large scale.

After Zhou Shiwu died of cancer in 2016, his son Zhou Liang took charge of the institute. Each of the 20 Yangtze sturgeon involved in the experiment were about 1.2 to 1.4 meters long.

Two days after being placed in the river, the fish began spawning. On March 26, many fry hatched from the eggs. The fry were about 5 or 6 millimeters long, like small tadpoles, with small tails and white bodies.

In recent years, many breeding sturgeon have been released into the Yangtze to allow them to grow freely, but researchers have never been able to monitor them in the river until now.

The fish were kept in cages for the experiment so that researchers could monitor them, the younger Zhou said.

"The IUCN declared the Yangtze sturgeon extinct in the wild because no Yangtze sturgeon had been found spawning in the wild for two decades. It's possible they have spawned in the wild, but researchers cannot find evidence of it," he said.

The sturgeon population declined sharply from the 1960s to the 1980s in the face of human activity, including overfishing with advanced tools, sand and rock dredging, navigation channel regulations and water pollution.

New experiments may be made in wider areas of the Yangtze in the wake of the successful spawning experiment, Zhou said.

For example, a wider body of water in the Yangtze will be blocked to conduct the experiment again. The ultimate goal, he said, is to release sturgeon into the Yangtze so that they can spawn and increase their populations naturally.