A group of volunteers claim to have discovered a white-flag dolphin nearly a decade after the animal was announced "functionally extinct."

Twenty volunteers started their search for the white-flag dolphin last Friday along the Yangtze River. They used cameras, sonar detectors and other recording equipment to collect data.

On Tuesday, volunteers claimed they found a dolphin in the Heishazhou section in Wuhu, Anhui Province. "Its body was white and it had a pointed mouth," said Song Qi, one of the volunteers. "We did not have time to take photos, but we submerged a sonar detector and hopefully we will receive a signal."

The sonar data, together with video footage and photos, was submitted to the Institute of Hydrobiology under the Chinese Academy of Sciences (CAS).

The white-flag dolphin is under first-class state protection and is among the 12 most endangered species in the world. In 2004, the body of a white-flag dolphin was found on the bank of the Yangtze, the last known sighting of the species.

In 2007, scientists announced that white-flag dolphins were "functionally extinct," meaning the population is too small the species cannot effectively reproduce.

However, Wang Kexiong with CAS did not rule out the possibility of seeing a white-flag dolphin today.

"'Functionally extinct' doesn't necessarily mean that the animal no longer exists," he said. "If any white-flag dolphins survive, they are most likely to be in the Anhui section, where there are many tributaries."

"It is possible that what they found was a white-flag dolphin," he added, "but we definitely need to analyze the data first."

During the past decades, many fishermen have claimed to have seen white-flag dolphins in the Yangtze River.

"Whatever the result is this time, the voluntary project will help to increase people's awareness of the need to protect the river," said Wang Ding, a research fellow with the Institute of Hydrobiology.

Wang also called for more of such activities in the future.