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.

Dolphin species	Number	Status	Location
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
Hector’s Dolphin	7,000	Endangered	Oceans
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.