- Date: September 10, 2015
When we think of dolphins and porpoises, we often don’t think of fresh water. But in parts of South America and Asia, several rivers are home to these charismatic species.
Dolphins are among the world’s oldest creatures, along with some species of turtles, crocodiles and sharks. They provide important indicators of the health of rivers.
WWF monitors populations of river dolphins and porpoises and strives to address the issues that threaten their future—which are the same threats that impact freshwater ecosystems overall. For example, we encourage local communities along rivers to use natural fertilizers, not dispose of sewage in rivers, reforest riverbanks, improve commercial fishing activities and drive policy changes that reduce impacts from industry.
Check out the questions and answers below to learn more about river dolphins and porpoises.
What’s the difference between a dolphin and a porpoise?
Dolphins and porpoises appear a lot alike. But the main difference between the two lies with their appearance. Dolphins sport longer snouts, bigger mouths, more curved dorsal fins, and longer, leaner bodies than porpoises.
How many species of dolphins and porpoises live in rivers?
Excluding the functionally extinct Yangtze river dolphin, there are seven species of dolphins and porpoises that live in fresh water: Indus river dolphins; Amazon river dolphins; Ganges river dolphins; Bolivian river dolphins; Yangtze finless porpoises; Irrawaddy dolphins; and, tucuxi. Populations of the Irrawaddy dolphin and tucuxi live in marine environments, and the Yangtze finless porpoise is a subspecies of the ocean-dwelling finless porpoise.
What threats do river dolphins and porpoises face?
Arguably the most significant threat is infrastructure—for energy, agriculture, flood control or otherwise. Infrastructure can degrade habitats, reduce food supplies, and fragment populations, dividing species into isolated groups. Unsustainable fishing is also a major challenge, as gillnets and other practices can directly harm or kill river dolphins and porpoises, and depletion of fish stocks can lead to starvation. Pollution from agriculture, industry and mining can make water—their home—toxic. And of course, climate change underscores these threats, making river dolphins and porpoises even more vulnerable.
Can river dolphins and porpoises see under water?
The Indus and Ganges river dolphins are both essentially blind. To hunt, they emit ultrasonic sounds that bounce of fish and other prey, enabling the river dolphins to “see” an image in their minds. This process is known as echolocation.
Why are river dolphins and porpoises important to river ecosystems?
River dolphins and porpoises serve as reliable indicators of a river’s overall health. An abundance of river dolphins is a sign of a healthy river; the decline is an indication that their river’s natural balance is critically disturbed. WWF surveys river dolphin and porpoise numbers to both determine their status and vulnerability and to gather an understanding of how the river, as a whole, is fairing.