A study described at Planet Earth Online reveals unexpected twists in the story of the Yangtze’s baiji river dolphins and their slide into extinction:
The dolphin was probably doomed by a combination of legal and illegal overfishing, heavy river traffic and pollution from farms, homes and industry. Some 10 per cent of the world’s population lives and works along the Yangtze, and the baiji has been among the losers in China’s swift economic development.
A team led by Dr Samuel Turvey of the Institute of Zoology, Zoological Society of London, travelled to China and interviewed around 600 fishermen on the Yangtze, asking questions about when and where they last saw a baiji.
‘The problem is that by definition before species go extinct, they become very rare and hard to find. This means we don’t have good information about the dynamics of species decline,’ Turvey comments. ‘But fishermen spend their whole working lives on the river, and we realised that we could use interviews with them not just for information on the baiji but also more general conservation biology data about how extinction happens.’
These interviews didn’t just add to the growing conviction that the baiji is gone forever; they suggested that it didn’t die out in the way currently accepted theories suggest it should have.
The baiji was declared officially extinct in August 2007, but was sighted on the river later that month. It appears certain that no viable breeding population survives, however.
The interviews conducted by Turvey’s group revealed much about the humans who work on the river, as well as the animals that lived in it:
‘It was very disconcerting how quickly people seem to have forgotten about these animals,’ Turvey comments. ‘We’d expected that there would still be memory among fishing communities of what the river used to be like, but we found that knowledge is disappearing fast.’
‘Even if younger people hadn’t seen a baiji themselves, we thought they’d have been told about them by the older fishermen,’ he adds. ‘But we could be sitting talking to one of the elders about when they used to see baiji, and their 40-year old son sitting next to them wouldn’t have any idea what we were talking about.’
