In 1998 there was an estimated total of only seven dolphins left. When the filling of the Three Gorges reservoir began in 2003, it seemed that the white dolphin was no more. While there were a few rare sightings at this time, the evidence was questionable.As it seemed pointless to return to China to try and find the Baiji, the new TV series instead turned its attention to the Blue Whale and visited the Sea of Cortez in Mexico for this Sunday's final episode.
When an expedition in search of living Yangtze dolphins began in November 2007, the results looked very grim. For seven months the Yangtze River was tracked with sophisticated equipment, including cameras and underwater microphones. But the once cheerful sounds of the talking dolphin were never heard. Nothing. The white dolphin had already left the world forever.
However, in the first episode "Amazon Manatee", Mark and Stephen were able to spend time with the Amazon Pink River Dolphin or "Boto", and got some marvellous footage and photographs.