Great stuff. Here's a page at Wired For Books with two nice audio interviews with Douglas Adams, the second of which from 1989 has Douglas talking about the plight of the Baiji Dolphin, but also promoting the second Dirk Gently book "The Long Dark Teatime of the Soul". Both interviews run around 25 minutes and can be found here:
"Douglas Adams interviews by Don Swaim (CBS Radio)". The
Last Chance To See part of the interview begins about 11:40 into the 1989 interview.
Replay Radio should serve me well again here...
In a second Douglas Adams interview, he talks with Don Swaim in 1989 about searching for the Yangtze River dolphin in China, promoting the conservation of wildlife, and his novel, The Long Dark Tea-Time of the Soul.