The center also offers "homes" for volunteers and tourists, who come to learn more about wetland protection and enhance their awareness about how to protect the wetlands and birds.

Wen Cheng, a member of the UNESCO World Heritage application committee under the National Forestry and Grassland Administration, says Beidagang will join the application of the Yellow and Bohai Seas' migratory-bird project.

Wen points out that the project has been supported by the International Union for Conservation of Nature since 2012, following a highlevel meeting in South Korea.

In 2016, the IUCN encouraged China to apply for UNESCO status for the sites. A growing number of international organizations have since expressed support.

Beidagang hosts 70 percent of the world's endangered Central Asian gulls.

A total of 276 avian species, including 11 under national protection, use the wetland.

The population of each species in Beidagang exceeds 1 percent of the global total, researchers say.

Tianjin was once the Yellow River's estuary. An ancient shell dam on the coastline may reveal the ancient sea's development.

"All these facts meet UNESCO's criteria," Wen says.

Beidagang Wetland covers nearly 350 square kilometers, including a core area of about 115 sq km, in the southeast of the Binhai New Area.

The city has released a comprehensive plan for the wetlands' protection from 2018 to 2021.

In 2019, the Binhai New Area reclaimed over 77 sq km of fishing areas as wetlands. It also reclaimed nearly 9 sq km of farmland, and relocated 10 enterprises and 24 families.

Shang Chenghai, deputy director of the reserve's administrative committee, says the water reserve has increased to 379 million cubic meters, and the wetland area has increased from 140 sq km to 240 sq km in the last two years.