This has been a very interesting thread with differing opinions without descending into a mudhole, as has happened to other threads of this nature!
I have nothing to add to the song's origin but this:
In early part of the last century fishermen from Nova Scotia and Newfoundland both sailed in Saltbank Schooners to common fishing grounds. Dories lowered from these schooners would fish trawl lines in close proximity to each other and the fishermen often sang to pass the time as they worked. Therefore these men would return to home port with newly learned songs exchanged both ways. No doubt in true folk tradition songs were modified to reflect local places and people. It is not at all surprising that similar folk songs were collected from distant places at about the same time.
The story of Aunt Virtue is fascinating and convincing as to her at least composing a version of the song!
It's because of threads like this that I love the Mudcat!