This may be a controversial statement but some book publishers have found that online book piracy may not be reducing sales of book publishers.
Just because you download, say, Freakonomics from one of the four download sites investigated by Attributor that publicly provide data on downloads (4shared.com, scribd.com, wattpad.com, and docstoc.com), does this necessarily mean you would otherwise have bought a legal copy of the book?
Attributor counted up 1,132 illegal downloads of Freakonomics – but is each a lost sale? That conclusion doesn’t hold up, says Shatzkin. Some downloaders might read a few pages and decide to delete the file (the online equivalent of thumbing through a book in a store and putting it back on the shelf). Others might already own a print copy but wanted a digital copy too, at no additional cost. There are as many reasons to download as there are downloaders. link.