The first-ever comprehensive review of the state of the world’s shellfish has just been released by The Nature Conservancy and the prognosis (as you may expect) really isn’t good. In fact, when oysters are concerned it’s downright awful.Globally, about 85% of the world’s oyster reefs have vanished and in many areas oyster reefs are functionally extinct:

http://www.treehugger.com/files/2009/05/85-percent-worlds-oyster-reefs-already-gone-many-functionally-extinct.php