I must confess this is one of those songs I happily hum harmonies to without listening to the words! Not sure why.

I suspect "Carrickfergus" (with a murky past itself) is a red herring, so to speak - the bits in common are floating verses that turn up in lots of places.

On Irish connections: I'm intrigued by "Scatterie", there being a Scattery Island in the Shannon estuary. The "starving slaves" phrase puzzles me - seems like a mishearing of some sort. No shortage of eels, incidentally, in the Shannon - though not big enough to spear!

Regards