Conservation: Humpback Whales Make a Comeback

Humpback whales are making a comeback more than 40 years after a ban on commercial hunting was brought in to save them from extinction.

Marine biologists estimate that the number of humpbacks worldwide may have grown to more than 40,000 adults and about 15,000 juveniles, following the ban that began in the 1960s. The International Union for Conservation of Nature (IUCN) has revised its classification of the whales as "vulnerable" to "of least concern" on its latest annual list of endangered animals.

The southern right whale population has also begun to recover - the number of these is believed to have doubled from 7,500 in 1997.

Randall Reeves of the IUCN said: "This is a great conservation success and shows what needs to be done to ensure these ocean giants survive."

The success of these two species, however, contrasts with a worsening trend for other cetaceans, including whales, dolphins, sharks and porpoises, of which 10% are classified as endangered or critically endangered. Furthermore, the picture is unclear for more than half of the world's 44 cetacean species, because too little is known about their populations.

Smaller coastal and fresh water species, including the vaquita porpoise, finless porpoise, South American river dolphin and Irrawaddy dolphin, are increasingly at risk of extinction.