Danube bleak by the building of dams across many of the rivers. Landlocked populations survive in small rivers and reservoirs, breeding in the small streams above the dams. The main Caspian Sea population has found ways of spawning below the dams. Overfishing and pollution in the Caspian Sea could impact on the Danube bleak but in 2008 the IUCN Red List of Threatened Species listed it as being of "Least concern". The Danube bleak feeds on small crustaceans, worms, molluscs, insect larvae, insects and small fish. Male Danube bleaks assemble in May to July at spawning sites in fast flowing streams with
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