"We were so excited to see two groups of finless porpoises on Aug 2. We seldom see them during our patrols along the river.

"They look so cute with their round heads and smiling faces," Hu said. "The species has lived in the river for 25 million years. It would be a shame if it becomes extinct due to human activity."

Although governments at different levels and enthusiastic volunteers have stepped up efforts in recent years to save the animals－China's only surviving aquatic mammal in inland waters－the effect of their efforts has been limited, as shown by statistics released by the Ministry of Agriculture and Rural Affairs late last month.

Vice-minister Yu Kangzhen said that according to a survey carried out by the ministry between Nov 10 and Dec 31, only 1,012 finless porpoises are living in the Yangtze and the freshwater lakes linked to it. There are 445 in the river's main channel and 567 in the Dongting and Poyang lakes.

A survey by the ministry in 2012 found 1,045 porpoises living in the river and the two lakes. While the number living in the lakes has risen, the number living in the Yangtze has declined dramatically.

Between 2006 and 2012, the number of porpoises dropped by more than 50 percent, making them rarer than wild giant pandas, the ministry said.

According to the 2012 Yangtze Freshwater Dolphin Survey Report by the then Ministry of Agriculture, the Institute of Hydrobiology at the Chinese Academy of Sciences, the World Wide Fund for Nature and the Wuhan Baiji Dolphin Conservation Fund, in 2006 there were about 500 porpoises in the mainstream of the Yangtze, down from 1,225 in 2006.

The report also found that the number of porpoises was declining by 13.7 percent a year, compared with 5 percent in 2006.

Other than the baiji dolphin, the finless porpoise is the only freshwater mammal to have been found in Asia's longest waterway. While the baiji dolphin, nicknamed "Goddess of the Yangtze River", was declared functionally extinct in 2007, the finless porpoise, nicknamed "Panda in the Water", has been listed as critically endangered by the International Union for Conservation of Nature.