dhampyresa

Oh! Sorry I wasn't clear in the post: that's the main impetus for the pirates (and thus, the plot). There's no animal life left (marine animals get to occasionally be ghosts) and very few plants left. It's very much implied that what human life is left won't last much longer than a few more years at most. The pirates have a plan to bring the seas back (for most of the book it is unclear both what that plan is and whether it would even work).