Still looking into the background on the song. Some sources say the music for Moorlough Shore is the same or similar to Foggy Dew.

There are ABC renditions of various versions of Foggy Dew here:
http://www.ibiblio.org/fiddlers/FOCH_FORG.htm

There are at least 4 or 5 different tunes that go by the name Foggy Dew. I've been trying to track down the actual song sources for each. A lot of the documentation I've run across online compares a version of Foggy Dew to some other song, but they might not necessarily have the version of Foggy Dew that sounds like that other song.

There does seem to be some similarity between Moorlough Shore and Sloan's Lamentation and also to the Foggy Dew in Joyce. Still looking into other variants.

Some information sources including Wikipedia reference Bodleian Broadside versions of Moorlough Shore dating back to 1886. However, when I search the Bodleian archive, the only references I can find are to Moorlough Mary dating to around that time. The words for Moorlough Mary (probably Roud 2742) are different from Moorlough Shore (Roud 2946).

If I can get a clearer picture of which variants of Foggy Dew come from which sources, I'll try to post some of it here. It's like trying to untangle a series of knots, but it's interesting to track down the histories of some of the tunes and how they evolved over time.