The fourth Yangtze finless porpoise scientific expedition kicked off on Monday in Wuhan City, central China's Hubei Province to survey the population, natural habitats and living conditions of the critically endangered species endemic to China's longest river.

Over 120 surveyors aboard 20 fishery law enforcement vessels set sail in the mainstream of the Yangtze River, its tributaries and major lakes, including Poyang Lake in east China's Jiangxi Province, to carry out the activity. They aim to get a complete picture of the living status of the porpoise and later offer guidance in the species' conservation.

Members of the fourth Yangtze finless porpoise scientific expedition search for the Yangtze finless porpoise. /Hu Dikai  

A member of the fourth Yangtze finless porpoise scientific expedition searches for the Yangtze finless porpoise. /Xu Chunyong  

Members of the fourth Yangtze finless porpoise scientific expedition search for the Yangtze finless porpoise. /Xu Chunyong  

Members of the fourth Yangtze finless porpoise scientific expedition search for the Yangtze finless porpoise. /Xu Chunyong  

The flag of the fourth Yangtze finless porpoise scientific expedition. /Xu Chunyong
 

Wang Ding, a researcher at the Institute of Hydrobiology under the Chinese Academy of Sciences, is the head of the technological group in the research team for this expedition and believes protecting the Yangtze finless porpoise is protecting the Yangtze River.

"The status of the Yangtze finless porpoise at the top of the food chain reflects the conditions of all aquatic biodiversity in the entire river, which is to say that it represents the ecology of the Yangtze. In this sense, protecting the Yangtze finless porpoise is protecting the Yangtze River," Wang said.

According to Wang, the expedition will also include studying some major threats to the porpoise.

"First of all, its population, its distribution and its habitats, then we'll be looking at the impact of human activities by monitoring the water quality and other aspects," he said.

According to the World Wildlife Fund (WWF), the Yangtze finless porpoise is the sole freshwater sub-species of the porpoise family living in the Yangtze.

After its more-storied cousin, the baiji dolphin, was declared "functionally extinct" in the same waters in 2007, experts believe the finless porpoise is the Yangtze's last surviving mammal.

The last survey, in 2017, put its population at about 1,012.