Conservationists warned the rare Chinese white dolphins, also known as pink dolphins for their unique colour, face extinction unless urgent action against pollution and other threats is taken.

Their numbers in Hong Kong waters have fallen from an estimated 158 in 2003 to just 78 in 2011, with a further decline expected when figures for last year are released next month, said the Hong Kong Dolphin Conservation Society.

Facing extinction: Chinese white dolphins, also known as pink dolphins. Credit:AFP

''It is up to the government and every Hong Kong citizen to stand up for dolphins. We risk losing them unless we all take action,'' society chairman Samuel Hung said.

Two weeks ago a tour guide from Hong Kong DolphinWatch spotted a group of pink dolphins helping a grieving mother support the body of her dead calf above the water in an attempt to revive it.