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
Bowhead whale Bowhead whale The bowhead whale ("Balaena mysticetus") is a species of the family Balaenidae, in parvorder Mysticeti, and genus "Balaena", which once included the right whale. A stocky dark-coloured whale without a dorsal fin, it can grow in length. This thick-bodied species can weigh from . They live entirely in fertile Arctic and sub-Arctic waters, unlike other whales that migrate to low latitude waters to feed or reproduce. The bowhead was also known as the Greenland right whale or Arctic whale. American whalemen called them the steeple-top, polar whale, or Russia or Russian whale. The bowhead has the largest mouth