London, August 12 : A new study by conservationists has revealed that a quarter of whales, dolphins and porpoises are threatened with extinction, with one in 10 species endangered to the very highest levels.
According to a report in The Independent, the International Union for the Conservation of Nature (IUCN) reports a change in the conservation status of a third of all marine mammals, with the majority said to be at a greater risk of extinction than before.
Critically endangered species include the Antarctic blue whale, Maui's dolphin, the Pacific grey whale and the Baltic harbour porpoise.
However, the international moratorium on whale hunting has helped both humpback and southern right whale populations make a comeback after decades of industrial hunting threatened their extinction, the IUCN said.
Both species were previously classed as "vulnerable" but are now listed as of "least concern".
"Humpbacks and southern right whales are making a comeback in much of their range, mainly because they have been protected from commercial hunting," said Randall Reeves, of the IUCN.
"This is a great conservation success and clearly shows what needs to be done to ensure these ocean giants survive," he added.
However, the updated list also revealed that while the lot of some cetaceans is improving, many coastal and freshwater species such as river dolphins are increasingly threatened with extinction due to human activities.
Fishing, habitat degradation, climate change and noise pollution in the form of military sonar and seismic surveys were also having a damaging effect.