Danube an important industry. The Upper Danube ecoregion alone has about 60 fish species and the Lower Danube–Dniester ecoregion has about twice as many. Among these are an exceptionally high diversity of sturgeon, a total of six species (beluga, Russian sturgeon, bastard sturgeon, sterlet, starry sturgeon and European sea sturgeon), but these are all threatened and have largely–or entirely in the case of the European sea sturgeon–disappeared from the river. The huchen, one of the largest species of salmon, is endemic to the Danube basin, but has been introduced elsewhere by humans. Important tourist and natural spots along the Danube include
What Bird is That? Edition What Bird is That?" was published by Australia's Heritage Publishing in 2011, the latest release of Cayley’s “big bird book” complete with Lindsey’s revisions. It is 832 pages, features 769 birds and includes all 460 of Cayley’s full-colour paintings, many showing groups of related birds. New to this edition was an accompanying e-book "What Bird Call is That?", which identifies and illustrates 101 birds from "What Bird is That?", as well as providing sound files of each featured bird’s distinctive call. The sound files were provided by David Stewart. "What Bird is That?" plays a central role in Australian