A spotted seal is released into the sea in Dalian, Northeast China's Liaoning province, April 16, 2021. (Photo: Xinhua)

Researchers and breeders have been keeping track of eight spotted seals released on Friday into the Bohai Sea in Dalian, Liaoning province, and say they have basically assimilated into wild groups.

"They are equipped with satellite tracking markers. In the past month, they've been trained to master such skills as independently hunting live fish and dodging fishing nets to survive in the wild," said Liu Youlin, deputy general manager of Dalian Sun Asia Tourism, which sent five captive-bred spotted seals into the ocean.

Liu said it was the first time that spotted seals bred in captivity had been sent into the wild to help increase the wild population of the endangered species.

Spotted seals are under top national protection in China.

Monitoring has shown that the spotted seal population in the Bohai Sea's Liaodong Bay is stable at about 2,000.

The release area near Huping Island in Dalian's Lyushunkou district is a natural habitat for spotted seals.

"Each year, about 200 seals come ashore and roam here before migrating to the sea," said Tian Jiashen, an associate researcher with the Liaoning Ocean and Fisheries Science Research Institute.

The researchers chose the area to help the seals integrate into the wild population.

In addition to the five born in captivity, three seals rescued by the institute-two early this year and one in 2017-were released into the ocean.

"They were released only when they reached the release standard after wild training," said Tian, who had been taking care of them.

When the two pups were rescued in March, they weighed only 25 kilograms each. "Now they've grown to 31 and 33 kilograms," he said.

Tian said that since 1992, when the provincial-level Dalian Harbor Seal Reserve was established, rescue and release work has been conducted every year. The reserve was upgraded to national level in 1997.

The institute rescued 10 spotted seals last year, he said. One died, but the other nine were released into the wild.

Dalian has implemented corresponding measures to strengthen the protection of the harbor seal population.

Government institutions, research institutes and ocean parks such as Sun Asia and Dalian Laohutan Ocean Park have been making efforts to protect the species.

Liu said Sun Asia is planning to set up a special wild training base and a conservation fund for spotted seals.