Dolphin species on four continents are in danger, warn various reports.

In Asia, the Taiwan Matsu's Fish Conservation Union says that only 60 to 90 Indo-Pacific humpback dolphins (Sousa chinensis chinensis) remain off the Taiwanese coast, fewer than half that existed just four years ago. The Union says the species could become extinct in that region in 10 years. Industrial development and pollution near the estuary of Taiwan's longest river, the Jhuoshuei River, is blamed for the decline.

Indo-Pacific humpback dolphins exist throughout Asia, Africa and Australia, but this particular population is isolated. The species have a very low birth rate and take 10 to 12 years to reach sexual maturity.

To protect the dolphins, the Union is calling for the public to purchase land near the estuary to preserve it from further development.

Farther south, scientists are working on a rescue plan to protect the Australian snubfin dolphin (Orcaella heinsohni), a rare species believed to number around 200 individuals. The snubfin was only recognized as its own species in 2005; until then, scientists considered them to be Irrawaddy dolphins (O. brevirostris).

The snubfin is also threatened by development, in this case along the Queensland coast. Fishing and an expansion of oil and gas exploration in the region could further tax the ability of the species to survive. "The loss of just two or three dolphins off Townsville in one year" could result in a population collapse in that area, the World Wildlife Fund's Lydia Gibson told the AAP news service. The WWF is helping to develop the rescue plan for the species.

On the other side of the world, 20 rare pink river dolphins (Inia geoffrensis) have been found dead in Peru, the victims of poisoning. Scientists are investigating the source of the poison, which they theorize could have come from toxins in the waterways or from fishermen who feared the dolphins would interfere with their nets. The pink river dolphins are legally protected in Peru.

Finally, there's the U.S., where the growing Gulf Coast oil spill could threaten 3,000 to 5,000 dolphins that are already in area.

Photo: Indo-Pacific humpback dolphin, courtesey of Wikipedia/Takoradee.