Catherine ~

According to The Ballad Index, it appears your mother's "mermaid" song is a variant of The Sailor and His Bride which was collected by Kenneth Peacock from Charlotte Decker in Parson's Pond, NL, and published with the title Early Spring in Peacock's Songs of The Newfoundland Outports. Peacock noted that it was a variant of The Young Bride's Lament, and "Aunt" Decker learned it from her mother ca.1890 when she was six years old. :)

GEST Songs of Newfoundland and Labrador