Well, I think it's actually interesting to see different artist take a variation on a same idea. (Pirate theme is hardly the most original thing--doesn't Namie's Play album has a pirate theme too?).
Although for some odd reason I think of Harujuku girls by Gwen Stefani
Although from the snippets, it seems like this doesn't really have a lot to do with pirates and mermaid except for one or two songs (Correct me if I'm wrong). Because the Pirate theme is so opened to interpretation (kind of like the different movies where they can be portrayed as "good" or "bad")