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
Common minke whale sharks have been found scavenging the blubber thrown overboard during Norwegian minke whaling operations off Svalbard. Great white sharks and blue sharks have also been observed feeding on a minke whale carcass off California. A new species of siboglinid annelid worm, "Osedax mucofloris", was discovered on the carcass of a 5.3 m (17.4 ft) female minke whale experimentally placed at a depth of 125 m (410 ft) in the North Sea. This genus of worm uses endosymbiotic bacteria to feed on the bones of whales that fall to the seafloor. Common minke whales are a host to a number of