Amateur investigators have reported spotting what they believe to be a baiji dolphin in a stretch of the Yangtze river in eastern China. The animal was declared “functionally extinct” in 2006 after researchers from six countries failed to find a single dolphin, and concluded there were too few left to save the species.

At around 9:20 a.m. on Tuesday, the team of 11 saw what looked like a dolphin in the Yangtze river close to the city of Wuhu, in Anhui province, while on a one-week expedition to look for the animal. The dolphin jumped out of the water in easy view of one of the team’s boats, which was around 100 meters away. People on the team’s second boat, which was around 300 meters away, also saw the animal.

According to Song Qi, the leader of the expedition, the animal breached the surface of the water more than once, allowing the team to get a good look at it. “I saw most of the body, and the second time around I saw its mouth and head,” Song said in a telephone interview with Sixth Tone. Song was on the second boat which was further away, but team members on the first boat got a better look at the creature. “The front boat saw it three times,” Song said. Song estimated that altogether six people on the investigation team saw the animal.

The team didn’t manage to capture conclusive evidence that what they saw was a baiji dolphin. Song said the camera they were recording with wasn’t able to capture the animal in detail because it was wide-angle. Specialists from CAS’s Institute of Biology are currently examining sonar signals that were recorded by the team on the expedition to look for evidence of the animal.

All members of the investigation team were hobbyists — Song himself works in the publishing industry — and immediately after the sighting, Song contacted specialists at the Institute of Hydrobiology at the Chinese Academy of Sciences in Wuhan, neighboring Hubei province, who arrived to join the expedition on Tuesday afternoon. The investigation concluded on Thursday without any further sightings of the animal.

Experts believe increased human activity along the Yangtze has contributed to the baiji dolphin’s demise.

Since the 1980s, China has pushed to develop the Yangtze into a major shipping route, building a series of locks and dams. These measures, combined with overfishing and the discharge of wastewater, have severely damaged the biodiversity of the river. Data from CAS show that a third of the river-dwelling species endemic to the upper-reaches of the Yangtze are at or near the point of extinction.

In 2006, a 40-day search for the Baiji dolphin took place that was financed by Swiss national August Pfluger. The investigation covered more than 3,000 kilometers in six weeks, and found no evidence that the dolphin still existed. Because of the extensive nature of the search, Pfluger concluded that the baiji was “functionally extinct” — meaning a very small number may still exist, but not enough to reproduce.

The last substantiated sighting of the dolphin happened in 2007, only months after the species was declared functionally extinct, when a baiji dolphin was captured on video. Since 2007 a number of uncorroborated sightings have occurred.

Tuesday’s sighting provides a glimmer of hope for people like Song, who believe there are still baiji living in the Yangtze, and who want to protect them. Preservationists have previously caught a baiji, in an effort to rear the species in captivity to ensure its survival, but the animal died shortly after being captured.

Despite a lack of concrete evidence, Song is convinced that the animal the team saw was a baiji dolphin. “No other creature could jump out of the Yangtze like that,” Song said. “All the eyewitnesses — which include fishermen — felt certain that it was a baiji dolphin.”

With contributions from Lu Hongyong.

(Header image: A Baiji swims in the pool at The baiji aquarium of the Institute of Hydrobiology of the Chinese Academy of Sciences, Wuhan, Hubei province, July 17, 2002. Hu Weiming/IC)