Given their migratory behavior, it is difficult to count the total population of dolphins on the planet.
Dolphins are warm-blooded, air-breathing mammals that belong to the order Cetacea — derived from the Greek word, “ketos,” meaning “large sea creature,” and the suborder Odontoceti, which means “toothed whales.”
There are at least 44 species of dolphins divided into oceanic and river families and they are found in waters all over the world. Getting an exact species count is difficult and somewhat confusing because dolphins are often reclassified. Adding to the confusion is some dolphins are also called whales, such as the Northern Right Whale Dolphin. In addition, dolphins travel in pods of between two and 30, and that number can swell to as many as several thousand during mating season, making an exact count even more challenging. Data is missing or deficient of some dolphin species as well.
Like so many animal species, dolphins are under siege from humankind’s excesses, such as urbanization, pollution, widespread use of gillnets by fishermen and, of course, human-caused climate change. Given the challenges animals face, more than 27,000 species are endangered right now — and these are other animals humans are driving to extinction.
|Amazon River Dolphin||Tens of thousands||Vulnerable||Amazon and Orinoco river basins|
|Atlantic White-Sided Dolphin||300,000||Least concern||North Atlantic Ocean|
|Australian Snubfin Dolphin||Several thousand||Vulnerable||North, East Australia, Papua New Guinea|
|Bolivian River Dolphin||5,000||Vulnerable||Rivers in Bolivia and Brazil|
|Bottlenose Dolphin||600,000||Least concern||Oceans|
|Chilean Dolphin||5,000||Near threatened||Coastal waters of Chile|
|False Killer Whale||60,000||Near threatened||Waters all over the world|
|Fraser’s Dolphin||320,000||Least concern||Oceans in deep water|
|Ganges River Dolphin||2,500-3,000||Endangered||Freshwater river in India|
|Hourglass Dolphin||144,300||Least concern||Antarctic and sub-Antarctic waters|
|Indo-Pacific Hump-backed Dolphin||2,500||Vulnerable||Southeast Asia|
|Indus River Dolphin||1,800-1,900||Endangered||Freshwater rivers in India and Pakistan|
|Irrawaddy Dolphin||92||Critically endangered||South and Southeast Asia|
|Killer Whale (Orca)||1,000 in Alaska||Data deficient||Open ocean|
|Long-finned Pilot Whale||Several hundred thousand||Least concern||Southern Hemisphere, North Atlantic Ocean|
|Melon-headed Whale||50,000||Least concern||Subtropical waters, Hawaii|
|Northern Right Whale Dolphin||68,000||Least concern||Northern Pacific Ocean|
|Pantropical Spotted Dolphin||2 million to 4 million||Least concern||Open ocean|
|Pygmy Killer Whale||40,000||Least concern||Deep, warm waters|
|Striped Dolphin||2 million||Least concern||Wider Caribbean Region|
|White-Beaked Dolphin||100,000||Least concern||North Atlantic Ocean|
There are at least five species of dolphins that are endangered or critically endangered, according to the conservation groups the World Wildlife Fund and the International Union for Conservation of Nature and Natural Resources. They are the Atlantic Humpbacked Dolphin, Ganges River Dolphin, Hector’s Dolphin, Indus River Dolphin, and Irrawaddy Dolphin.
Aggressive fishing almost brought about the demise of the spinner dolphin in the eastern Pacific Ocean. In the 1980s, fisheries focused on the yellowfin tuna as it soared in popularity in restaurants and kitchens, and for reasons not fully known, the yellowfin schooled with the spinner dolphin. Millions of spinner dolphins were accidentally caught and killed when the fishermen set up nets around dolphin pods to catch the tuna.
It is believed that the spinner dolphin is one of the most common species of dolphin, along with the bottlenose, though its numbers, at least in Australia’s Darwin harbor, have halved in seven years.
We’ve recently lost one dolphin species. The baiji or Yangtze River dolphin, is believed to be the first dolphin species that humans have made extinct. The mammal succumbed to pressures exerted by the surging urbanization of China that began in the late 20th century. The baiji also became regularly enmeshed in fishing equipment and its habitat was destroyed as a result of the construction of the gigantic Three Gorges Dam that was completed in 2006. The current ongoing wave of animal and plant extinction, the worst since the dinosaur era — and these are the species that may have recently gone extinct.
The future does not bode well for some species of dolphin. Thomas A. Jefferson, a marine mammal biologist with Clymene Enterprises in Lakeside, California, has written extensively about at-risk dolphins and other cetacean species. He wrote in a chapter of his paper, “Endangered Odontocetes and the Social Connection: Selected Examples of Species at Risk,” that the Atlantic Humpback Dolphin is among the animal species that will go extinct in modern times.
“There is no doubt that several cetacean species (and many other populations) are in danger of extinction in the next decade or two,” he wrote. “That this is the case in a world of great human wealth and enormous technical achievement is a sad statement on our lack of concern for the natural environment.