I came across mention of this Fort Fisher Mermaid as being located at the North Carolina Museum of the Bizarre in Wilmington.
I was unable to find our anything at all about it other than one source saying the mermaid is a Cape Fear local legend.
The museum is located at 201 S. Water Street, next to the Cape Fear Serpentarium.
Next Time There, I Will Have to Check This Mermaid Out. --Old B-Maid