About the species
There are more than 30 species of dolphin. Most live in oceans across the world, but there are also six species of river dolphins, found in Brazil, China, Colombia, India, Nepal and Pakistan.
A number of dolphins are classified as endangered or critically endangered on the International Union for Conservation of Nature's Red List of Threatened Species, and many more are known to be in serious danger but have yet to be formally assessed.
The dolphin is generally a social animal, sometimes living in pods of several hundred.
Dolphins’ echolocate by producing clicking sounds and then receiving and interpreting the returning echos. From this they can tell the size, shape, distance, speed and direction of the objects – especially their favoured food of fish and squid.
Dolphins are larger than porpoises and have cone-shaped rather than spade-shaped teeth. They have a dorsal fin shaped like a wave, instead of the porpoises’ triangular fin, and often have a beak-shaped nose which porpoises never do.
Challenges and threats
One of the greatest threats to dolphins is accidental entanglement in fishing gear – which can cause them to drown. Known as bycatch, this causes the deaths of more than 300,000 cetaceans (dolphins, porpoises and whales) every year.
Depletion of the dolphin’s prey as a result of unsustainable commerical fishing is another reason for its decline.
The dolphin is threatened by chemical pollution in rivers, lakes and estuaries. Noise from naval operations and seismic surveys affects their echolocation, which can cause them to become stranded on shore. Being struck by ships and other sea vessels can also cause serious and even fatal injuries to dolphins.
The freshwater dolphin is vulnerable to human activities. It is at risk from man-made structures such as dams and barrages, which restrict its movement and affect its access to prey and suitable habitat.
WWF in action
In the UK, WWF has been campaigning for new marine legislation to ensure developments at sea progress in harmony with the whole ecosystem. Finally, in December 2008, the government introduced a Marine and Coastal Access Bill into the UK Parliament. The new legislation must improve the way our seas are managed across the UK, while protecting our valuable marine wildlife including dolphins.
We promote ways to reduce bycatch by changing the way fish are caught. We are working with fisheries managers and governments around the world to create, implement and enforce better fishing policies. This includes introducing more selective fishing gear, and educating people in the industry, as well as consumers, to purchase seafood sourced from responsible fisheries.
To halt the decline of the freshwater dolphin, WWF is supporting projects to reverse the degradation of freshwater habitats. For example, in China, WWF is working in the Yangtze River Basin to improve freshwater habitats and resources for both people and wildlife.
In 2004, WWF helped to re-establish the natural flow of water between Tian'e-zhou lake and the Yangtze river for the first time in 50 years. This has boosted the level and quality of the water in the lake, which is home to the Yangtze finless porpoise. This now allows the natural migration of fish during their breeding season.