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
Cryptid whale Another argued hypothesis is that that pod was part of an inbred population, which led to the mutation. Another possibility is that Quoy and Gaimard observed specimens which were neither deformed nor members of an unknown species or population, but rather mistaken identification of a pair of beaked whales that, by perspective, appeared to be one single creature. The high-finned sperm whale, or the high-finned cachalot, is an alleged variant or relative of the known sperm whale, "Physeter macrocephalus", with an unusually tall dorsal fin from the North Atlantic. The physician Sir Robert Sibbald, in 1687, described an alleged stranded