7 Cetaceans at Risk of Extinction

Red-Listed and Critically Endangered Dolphins, Porpoises, and Whales

Right Whale with Seaweed
Right Whale with Seaweed
Mark Hoffman and Bruce Long / CC BY-SA (https://creativecommons.org/licenses/by-sa/4.0)

When we think of oceans we often conjure images of graceful ocean giants breaching the surface of the sea or imagine the exhilaration of seeing a pod of dolphins playing in the surf. These fascinating marine mammals, cetaceans, are the descendants of land-dwelling animals that lived 50 million years ago. The original land-dwelling animals evolved to become better adapted to the marine environment, slowly becoming fully dependent on the ocean.

According to the World Cetacea Database, there are 86 known species of cetaceans inhabiting the world’s waterways, from the enormous Blue Whale, which weighs between 100-150 tons, to the smallest of the cetaceans, Hector’s Dolphins, at just 110 pounds.

Unfortunately, humankind has not been kind to the environment. Plastic bags floating through the ocean like strangely wrinkled jellyfish become deadly when they are ingested, the heavy metals and oils that contaminate the ocean damage the internal organs of these buoyant giants, and noise pollution from shipping barges and other modern vessels cause chronic confusion and stress.

Extinction is a real possibility for many of these extraordinary marine mammals

This list covers seven of the most critically endangered cetaceans, each with a worldwide population of fewer than two thousand individuals.

1. Atlantic Humpback Dolphin (Sousa teuszii)

Atlantic Humpback Dolphins are medium-sized dolphins, generally somewhere around 550-630 pounds, with a distinctive hump underneath their small, triangular dorsal fins. The Atlantic Humpback Dolphin calls the coastal waters along the northwestern portion of the African continent home.

“Humpback Dolphins – Flickr – GregTheBusker” by Greg Schechter from San Francisco, USA is licensed under CC BY 2.0

While these intelligent animals are known to fish cooperatively with the Imragen people, an ethnic tribe of fishermen, they are otherwise shy, so we don’t have a lot of information about their daily habits. They forage close to shore and are generally seen in groups of 1-8 animals, although larger groups of 20-40 dolphins occasionally congregate. 

Their habit of sticking close to shore puts Atlantic Humpback Dolphins at greater risk of getting tangled in gill nets, as well as making them easier for poachers to hunt. Due to fishing accidents, hunting, and marine pollution, their population has become extremely fragmented and the numbers of Atlantic Humpback Dolphins have dropped to approximately 1,500 mature individuals and appear to be rapidly decreasing.

2. Yangtze Finless Porpoise (Neophocaena asiaeorientalis ssp. Orientalis)

The Yangtze Finless Porpoise is a particularly unique cetacean. Not only is it one of just seven members of the genus neophocaena, the only genus of porpoise without a dorsal fin, it is also one of just a handful of freshwater cetaceans living on this planet. These porpoises are small compared to many other cetaceans, weighing in at just 150 pounds, and are a vital part of the Yangtze River ecosystem.

These porpoises are small compared to other cetaceans, weighing in at just 150 pounds, and their rounded heads and cute, “smiling” faces endear them the local populace, but they are also an important predator in the river’s ecosystem. Their small size and maneuverability allow Yangtze Finless Porpoises to live and hunt effectively in the river—preventing destructive imbalances in the food chain.

Heavy fishing activity, high levels of pollution, and hectic traffic on the Yangtze river have taken a toll on this extraordinary creature’s population. It has plunged in the last few decades, dropping from around 2500 individuals in the early 1990s to an estimated 1000 remaining individuals today.

To preserve the declining population of Yangtze Finless Porpoises and other rare Yangtze residents, China has imposed a ten-year fishing ban, starting in 2021. Several specimens of Yangtze Finless Porpoise have also been transplanted from the busier parts of the Yangtze River to nearby reserves designed to give the animals a chance to thrive away from the polluted and highly trafficked Yangtze. So far, approximately 85 individuals call these calmer waterways home.

"File:Qiqi, a Chinese River Dolphin (Baiji) 17.jpg" by unknown is licensed under CC BY-SA 4.0

The Yangtze Finless Porpoise was once one of two endangered species of cetacean living in China’s Yangtze River. Until 2006,  they shared the waterways with the Yangtze River Dolphin as well.

Better known as the Baiji dolphin, these elegant creatures were nicknamed “Goddess of the Yangtze” and were regarded as goddesses of protection, peace, and prosperity.

Just 13 animals were spotted during a 1997 survey of the river and none were located when they searched again in 2006.

3. North Atlantic Right Whale (Eubalaena glacialis)

North Atlantic Right Whales are baleen whales that weigh around 70 tons by the time they reach adulthood. All three varieties, the North Atlantic, North Pacific, and Southern Right Whale, lack a dorsal fin, much like the Finless Porpoises. These huge cetaceans feed on krill and small fish throughout the Atlantic Ocean by straining the seawater through their enormous baleen plates.

Right Whales can be distinguished from other whale species by their huge heads— which are around a quarter of the length of their body—and their v-shaped blowhole. They also have rough white patches of keratinized skin on their heads known as callosities whey they host thousands of tiny crustaceans known as cyamids, or whale lice. These patches of skin are often present at birth and are not caused by the external environment.

Currently, the lifespan of North Atlantic Right Whales is around 45 years for females and 65 years for males, although it is believed that their lifespan could reach as much as 70-100 years in some cases. Due to their long lifespan, migratory, and gestation periods, changes in the environment can have an extended effect on their population.

Once abundant in the North Atlantic Ocean, the current population of North Atlantic Right Whales is believed to have been reduced to around 400 individuals. While bans on hunting and shifts in oceanic shipping lanes have reduced deaths, collisions with ocean-going vessels and climate change are still major conservation problems for these stately cetaceans.

4. Irrawaddy Dolphin (Orcaella brevirostris)

Irrawaddy Dolphins inhabit the coastal waters of South and Southeast Asia, as well as the Ayeyarwady, the Mahakam, and the Mekong Rivers. At first glance, you might think you were seeing an out of place baby Beluga whale, with their beakless smiles and bulging forehead.

Irrawaddy dolphins are considerably smaller than their whale cousins—just 200-440 pounds compared to the Beluga’s 3000 pounds—and they have a low but distinctive dorsal fin. Not only are these slow-moving marine mammals an important source of marine tourism for the area, but they are also regarded as sacred animals by both the local Khmer and Lao people.  

"File:DKoehl Irrawaddi Dolphin jumping.jpg" by Dan Koehl is licensed under CC BY 3.0

Population increasing!

DKoehl Irrawaddi Dolphin jumping by Dan Koehl is licensed under CC BY 3.0

Conservation measures implemented in the mid-2000s banned the use of poison or dynamite while fishing, the Cambodian government began promoting the animals as a tourist attraction, and in 2012 an entire stretch of the river was deemed a protected zone. While the populations of most of the cetaceans on this list are in decline, it seems that conservation efforts on behalf of the Irrawaddy Dolphin have been successful. A survey in 2019 indicated that the population of Irrawaddy Dolphins had increased to approximately 92, the highest has been seen in over 20 years.

5. Māui dolphin (Cephalorhynchus hectori maui)

Māui dolphins are a subspecies of the smallest dolphin species—the Hector’s Dolphin. Hector’s dolphins are tiny for cetaceans just 110 pounds at maturity, and their light gray bodies and dark fins, flukes, and faces that give them a striking appearance. Typically found in groups of 3-5 individuals they usually congregate with their same-sexed podmates. Larger, mixed-sex groupings occur only occasionally, usually to forage or for mating purposes.

“Maui’s dolphin” by vivtony00 is licensed under CC BY 2.0

Only around 55 adult Māui dolphins remain alive today. Not only have these small dolphins had to contend with deaths from fishing nets and boat strikes, but they are also beset with diseases that usually only affect terrestrial animals. Both toxoplasmosis and brucellosis can cause spontaneous abortions and other fatalities for dolphins, and both have been discovered during necropsies of Māui dolphins.

6. North Pacific Right Whale (Eubalaena japonica)

The North Pacific Right Whale is closely related to the North Atlantic Right Whale. Like their siblings in the Atlantic, they are baleen whales with enormous heads, approximately a quarter of their overall length, with which they support their heavy baleen plates.

Callosities—sections of keratinized skin that provide a habitat for tiny crustaceans called cyamids—are characteristic of this species as well. These callosities often form behind the whale’s blowhole, appearing very much like a white bonnet.

These species is a particularly sociable group of animals among cetaceans. These gentle giants have been seen in the company of both humpback whales and Western gray whales, although they are understandably wary of human vessels and they tend to avoid contact. Their movement and migration throughout the ocean is largely a mystery due to their elusive nature.

Like their close relative the North Atlantic Right Whale, the North Pacific Right Whale was once abundant in their realm. Before commercial whaling of the Pacific Ocean began in the 1930s it is believed that at least 20,000-30,000 of these graceful, serene cetaceans filled the oceans. Between 1840-1849 it is estimated that that between 21,000 and 30,000 whales were killed for their blubber and bones. The population has never recovered. It is believed that between 30-40 individuals are living today.

7. Vaquita (Phocoena sinus)

The Vaquita, a tiny porpoise that rarely reaches five feet long, is the rarest cetacean in the world. This species was discovered off the coast of Mexico in 1958, the only area in the world where they are present. Vaquitas have black rings around their eyes and black lining their lips, adaptions believed to help them hunt in the murky water near the shore.

“Vaquita Marina” by SEMARNAT is licensed under CC PDM 1.0

Unfortunately, their hunting habits also bring them in close proximity to gill nets, which often results in the entanglement and subsequent death of the little marine mammals. While fishing laws have been enacted to prevent this from happening, illegal poaching of the rare Totoba fish—prized for its swim bladder which is used in Chinese medicine—still threatens the survival of the species today.

The population of Vaquita porpoises has dropped from around 600 individuals in 1997 to an estimated 10 remaining alive today.

Many of these species could be completely wiped in just a few short years if conservation efforts are not successful. Fortunately, there are many conservation groups around the world dedicated to protecting these rare treasures. From giants like the World Wildlife Fund, which labors to protect many species of endangered animals worldwide, to more focused conservation groups such as VaquitaCPR, dedicated to just one species, human beings are doing what they can to preserve and protect these fascinating creatures.

If you are interested in helping conservation efforts, click the link below to explore the list compiled by SeetheWild.org.

Whale conservation organizations

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