More than 80 aquatic animal rescuers are now involved in the search for an injured finless porpoise in the country's largest freshwater lake.

In addition, more than 2,000 fishermen have also been mobilized on Poyang Lake to report traces of the finless porpoise - an endangered mammal considered rarer than China's giant panda - which is known to have life-threatening injuries.

"There are less than 1,000 finless porpoises in China, and the number is declining by 13.7 percent each year," said Hao Yujiang, a researcher at the Chinese Academy of Science's Institute of Hydrobiology, who led a team of six from his institute to join the rescue mission on Monday.

Volunteers first saw the mammal, which is similar to a dolphin in appearance, on Feb 5 in Yugan county, Jiangxi province. Photos showed a large fishhook in the back of the porpoise. Rescuers said they saw the porpoise several times, but that it disappeared before they could help.

"The photos showed signs of infection in the wound, meaning rescuing the porpoise is a matter of urgency," Hao said.

The team is prepared to provide medical treatment, and the purpoise might have to be sent to Wuhan, capital of Hubei province, where the institute is headquartered, for further treatment, he added.

Another three local rescue teams as well as two from Hubei province also joined the rescue efforts, bringing the total number of rescuers in the six teams to more than 80.

The local fisheries bureau has distributed notices asking more than 2,000 fisherman to help track down the porpoise, Zhang Jinyang of Yugan county's fisheries bureau told Changjiang Daily, which is headquartered in Wuhan.

Human activities have put the existence of the finless porpoise at great risk, Hao said. "Shipping, fishing, construction and sand excavation in the Yangtze River are all to be blamed for the mammal being endangered."

Zhu Jiang, head of the World Wildlife Foundation's Yangtze River biodiversity conservation project, said, "in previous years, there was a lack of recognition of the finless porpoise's situation in China and government resources to support the mammal's protection were far from enough."

The situation has improved to some extent in recent years, with the Ministry of Agriculture classifying the mammal as a first-class national protected species in 2014, and a plan for its protection being drafted late last year, Zhu said.

However, many issues, such as overfishing and sand excavation, still hinder the mammal's protection, he added.

The finless porpoise's habitat may be further worsened as the Jiangxi government plans to build a series of sluice gates in areas that link Poyang Lake to the Yangtze River to keep water in the lake during winter months, as the lake has been suffering from worsening drought over the past decade.

The mammal's habitat is mainly located in the lower reaches of the Yangtze River, and about 450 of them live in Poyang Lake. (China. org)