Last week, a group of amateur naturalists claimed to have spotted a species of river dolphin declared extinct over a decade ago: the baiji, also known as the Yangtze River dolphin. The news generated lots of excitement online – but even if these reports can be confirmed, they're unlikely to alter the fate of the doomed dolphin, experts say. Instead, we should be focusing our efforts on saving another Yangtze resident while there is still time.

The sighting allegedly occurred after a week-long expedition covering a 200-kilometre stretch of China's Yangtze River between the cities of Anqing and Wuhu. Expedition leader Song Qi expressed confidence that his team of volunteers and dolphin enthusiasts had observed a baiji jumping out of the water. "All the eyewitnesses … felt certain that it was a baiji dolphin," Song told Sixth Tone, an online news portal overseen by the Chinese government.

While no video or photographic evidence of the event was provided, Song is hopeful that his team's sighting might kickstart conservation efforts to save the species. "I want society to realise that the baiji is not extinct,” he told The Guardian.

However, conservation biologist and baiji expert Samuel Turvey of the Zoological Society London remains unconvinced. Turvey was a key member of a 2006 expedition that found no evidence of the river dolphin in the Yangtze, resulting in the species being declared functionally extinct. "Extreme claims for the possible survival of probably extinct species require robust proof, and while I would deeply love there to be strong evidence that the baiji is not extinct, this isn't it,” he told National Geographic.

The large-scale 2006 survey was initiated by China's Ministry of Agriculture, and involved scientists and volunteers from the Swiss Federal Institute of Aquatic Science and Technology, the National Oceanic and Atmospheric Administration and the Hubbs-Seaworld Institute. Over a period of 40 days, the team covered more than 3,000 kilometres of the Yangtze – without a single sighting. The resulting scientific publication suggested that even if a few baiji were still clinging on to survival, the fate of the dolphin was sealed. "[T]he species has no hope of even short-term survival as a viable population in the river."

The Yangtze region is home to 10% of the world's human population, which has had a massive impact on the river, clogging it with boat traffic and fishing activity. Accidental by-catch from this fishing industry was the primary reason for the baiji's demise – its numbers plummeted from over 6,000 in the 1950s to 400 in the 1980s. By 1999, just 13 baiji remained in the wild, with the last verified sighting taking place in 2002 (a previous rumour of a baiji sighting in 2007 turned out to be a Yangtze finless propoise).

And even if a handful of the dolphins still exist, conservation experts like Turvey see no hope in saving them. Without unprecedented financial investment and political will, it seems unlikely that any remaining baiji – if indeed there are any – could be captured and bred in captivity. In his book Witness to Extinction, Turvey recounts the disheartening struggle to find any remaining survivors back in 2006. "[F]or almost thirty years, scientists and conservationists have repeated time and again what needed to be done to save the baiji," he writes. And yet despite conservation efforts when its numbers were still viable, the baiji was "allowed to slip unchecked towards extinction."  

Now, Turvey suggests that we stop chasing "the ghosts of baiji" and focus our efforts on saving another Yangtze species while there is still time. The Yangtze finless porpoise is a freshwater cetacean that faces similar threats to the baiji from the increasingly hostile habitat in the river. It's currently listed as Critically Endangered, with between 500 and 1,800 animals remaining.

This is a timely if not urgent warning, especially since Turvey and his colleagues rang the alarm bell over a decade ago. "The situation of the finless porpoise is just like that of the baiji 20 years ago," said Wang Ding of the Institute of Hydrobiology, Chinese Academy of Sciences in a statement released after the 2006 expedition. "If we do not act soon, they will become a second baiji."

Efforts are underway to help conserve the porpoise, including relocating individuals to safer, less polluted areas of the river. But scientists are warning that we need to do more. "The time remaining in which to save this endemic porpoise may be shorter than previously anticipated," suggested researchers in a recently published study. According to their estimates, the porpoise could go the way of the baiji within the next 25 years.

Turvey echoed these sentiments recently in response to the latest sighting rumours, suggesting that it's not the baiji but the Yangtze finless porpoise that needs our help. "This animal needs urgent media interest and conservation attention in order to combat its total population collapse, while there is still time to do something about it."