That's bad news, because in many ways it's a microcosm and great big sign saying: "Something's wrong people".
Does anyone remember the programme made by BBC Radio 4, also broadcast on the BBC WS many years ago in which two intrepid reporters went down the Yangtze trying to spot this rare species?
It was a wonderful piece of theatre radio; the water sound effects, the reporters themeselves, and one thing they did which will live with me forever. In fact, I tried it on my underwater dive in Gallipoli.
In an attempt to record the dolphins they put a condom over a microphone with a long lead lowered into the river.
If my memory serves me well you did hear the clicks of the dolphins; they would have attached the mic to a special unit.
I did the same with some divers coming out of the Dardanelles at 15 metres decoing - the point where divers wait to flush out/equalise air in their blood.
If only such ingenuity in tracking down these creatures could be used to save them as well