The original version of the "Great Silkie of Sule Skerry" comes from the Orkney Islands (off the North coast of Scotland). I have the words, the original tune (midi file), and several links to Silkie lore HERE.
The original tune for this song was nearly lost, but was noted down in 1938 by Dr. Otto Anderson, who heard it sung by John Sinclair on the island of Flotta, Orkney. He said, "I had no idea at the time that I was the first person to write down the tune. The pure pentatonic form of it and the beautiful melodic line showed me that it was a very ancient melody that I had set on paper." I much prefer this version to that of Joan Baez.

Cheers, S. in Seattle