Researchers from the Chinese Academy of Sciences' Institute of Hydrobiology give a health check to one of the captive porpoises. [Photo by Fu Jianbin/China Daily]

Scientists predict that without efficient protection, the finless porpoise will also disappear in five to 10 years.

Wang said overemphasis on the Yangtze River's economic value and ignorance of its natural attributes had resulted in deterioration of the aquatic mammals' habitat.

Many porpoises have been found wounded or dead in recent years as a result of starvation, pollution-induced disease or injuries inflicted by ships' propellers.

In 2016, China released a guideline to increase traffic along the Yangtze, part of efforts to build an economic belt along the river. It emphasized that development should not be at the cost of environmental-protection measures.

"We are working on more comprehensive measures to protect the environment along the Yangtze River," said Li Yanliang, a Ministry of Agriculture official.