14 Most Endangered Whales, Porpoises, and Dolphins

Two gray Irawaddy dolphins poke their heads out of the water
Gerard Soury / Getty Images

Cetaceans, the infraorder of aquatic mammals consisting of whales, dolphins, and porpoises, are some of the most unique animals on earth, but they are also some of the most endangered. Cetaceans are divided into two distinct groups, with members of each group facing unique threats to their survival.

Members of the first group, the Mysticeti or baleen whales, are filter feeders characterized by their baleen plates, which they use to filter plankton and other small organisms out of the water. The diets of baleen whales allow them to accumulate large quantities of blubber, which made them favorite targets of 18th- and 19th-century whalers seeking to boil down blubber into valuable whale oil. Centuries of intensive hunting left most baleen species in shambles, and since they reproduce slowly, scientists worry that they're now more vulnerable to threats like pollution and ship strikes that might have otherwise been minor. Although commercial whaling was banned in 1986 by the International Whaling Commission (IWC), some species like the sei whale are still heavily targeted by Japan, Norway, and Iceland, which dodge or defy the IWC moratorium.

The second group of cetaceans, the Odontoceti or toothed whales, includes dolphins, porpoises, and whales like sperm whales, all of which possess teeth. While this group of cetaceans was not heavily targeted by whalers, many species still face threats of extinction. Dolphins and porpoises are severely threatened by incidental entanglement in gillnets, which accounts for a vast majority of human-caused dolphin and porpoise deaths. Furthermore, climate change and the increased presence of humans in bodies of water around the world pose threats to all cetaceans. Today, the International Union for Conservation of Nature (IUCN) lists 14 of the 89 extant species of cetaceans as Endangered or Critically Endangered, including five endangered whale species, two endangered porpoise species, and seven endangered dolphin species.

of 14

North Atlantic Right Whale - Critically Endangered

a gray North Atlantic right whale swimming in the ocean

NOAA Photo Library / Flickr / CC BY 2.0

Right whales were among the whales most heavily targeted by whalers in the 18th and 19th centuries, as they were some of the most convenient to hunt and also had a high blubber content. Their name comes from the whalers' belief that they were the "right" whales to hunt since they not only swam near shore but also floated conveniently on the surface of the water after being killed. There are three species of right whale, but the North Atlantic right whale (Eubalaena glacialis) has suffered some of the greatest population declines, making it the most endangered whale species on the planet and causing the IUCN to list it as critically endangered.

Today, there are fewer than 500 individuals on earth, with around 400 individuals in the western North Atlantic and a population in the low double digits in the eastern North Atlantic. The eastern North Atlantic population is so small that it is possible this population is functionally extinct. While the species is no longer hunted by commercial whalers, it still faces threats from humans, with entanglement in fishing gear and collisions with ships posing the most significant dangers. In fact, North Atlantic right whales are more susceptible to ship collisions than any other species of large whale.

Over the past decade, there were at least 60 recorded North Atlantic right whale deaths that resulted from net entanglement or ship strikes, a highly significant number considering the small global population size of the species. Furthermore, an estimated 82.9 percent of individuals have been entangled at least once and 59 percent have been entangled more than once, revealing net entanglement to be a serious threat to the survival of the species. Even when entanglements are not fatal, they nevertheless physically damage the whales, which can lead to lower reproduction rates.

of 14

North Pacific Right Whale - Endangered

a gray North Pacific right whale emerging from the water

Mark Hoffman and Bruce Long / Wikimedia Commons / CC BY-SA 4.0

Along with the North Atlantic right whale, the North Pacific right whale (Eubalaena japonica) was one of the whale species most heavily targeted by whalers. It was once abundant in the northern Pacific Ocean off the coasts of Alaska, Russia, and Japan, although the exact population numbers for the species prior to whaling is unknown. During the 19th century, an estimated 26,500-37,000 North Pacific right whales were caught by whalers, of which 21,000-30,000 were caught in the 1840s alone. Today, the global population for the species is estimated to be less than 1,000 and probably in the low hundreds. In the northeastern Pacific Ocean around Alaska, the species is almost extinct, with an estimated population size of 30-35 whales, and it is possible that this population is too small to be viable as only six female North Pacific right whales have been confirmed to exist in the northeastern Pacific. The IUCN has therefore listed the species as endangered.

Commercial whaling is no longer a threat to the North Pacific right whale, but ship collisions prove to be one of the biggest threats to their survival. Climate change is also a serious danger, especially because reductions in sea ice coverage can dramatically alter the distribution of zooplankton, the main food source for North Pacific right whales. Noise and pollution also threaten the survival of the species globally. Furthermore, unlike other endangered whale species, which can be reliably found in wintering or feeding grounds, there is no place to reliably find North Pacific right whales. They are therefore rarely observed by researchers, hindering conservation efforts.

of 14

Sei Whale - Endangered

a blue sei whale swimming underwater

Gerard Soury / Getty Images

The sei whale (Balaenoptera borealis) is found in every ocean on earth but wasn't widely hunted in the 19th and early 20th centuries because it was thinner and less blubbery than other baleen species. However, by the 1950s, whalers began heavily targeting sei whales after populations of more desirable species like right whales were decimated as a result of overexploitation. The harvesting of sei whales peaked from the 1950s until the 1980s, reducing the global population dramatically. Today, sei whale populations are approximately 30 percent of what they were prior to the 1950s, causing the IUCN to label the species as endangered.

Although sei whales are now rarely caught by whalers, the Japanese government allows an organization known as the Institute of Cetacean Research (ICR) to catch approximately 100 sei whales annually for the purpose of scientific research. The ICR is highly controversial and has been criticized by environmental organizations such as the World Wildlife Fund (WWF) for selling whale meat harvested from the whales that it catches and for producing very few scientific papers. These environmental organizations accuse the ICR of being a commercial whaling operation masquerading as a scientific organization, but despite a 2014 ruling from the International Court of Justice that the ICR's whaling program was not scientific, it continues to operate.

Sei whales were also the victims of the largest mass beaching ever observed when scientists discovered at least 343 dead sei whales in southern Chile in 2015. While the cause of death was never confirmed, the deaths are believed to have been caused by toxic algal blooms. These algal blooms may continue to be a significant threat to sei whales as climate change causes ocean waters to warm and algal blooms develop better in warmer waters.

of 14

Blue Whale - Endangered

a gray blue whale swimming underwater

eco2drew / Getty Images

The blue whale (Balaenoptera musculus) is the largest animal ever known to exist with a maximum length of around 100 feet and a maximum weight of about 190 tons. Prior to the influx of whaling in the 19th century, the blue whale was found in all of the world's oceans in abundant numbers, but over 380,000 blue whales were killed by whalers between 1868 and 1978. Today, the blue whale is still found in every ocean on earth but in far smaller numbers, with an estimated global population of only 10,000-25,000 — a sharp contrast from the estimated global population of 250,000-350,000 at the start of the 20th century. The IUCN has thus listed the species as endangered.

Since the dissolution of the commercial whaling industry, the largest threat to blue whales has been ship strikes. Blue whales off the southern coast of Sri Lanka and off the west coast of the United States are especially susceptible to ship strikes due to the high volume of commercial ship traffic in these areas. Climate change is also a serious threat to the survival of the species, especially because warming waters lead to declines in populations of krill, which are the main food source of blue whales.

of 14

Western Gray Whale - Endangered

a gray whale leaping out of the water

Bill Baer / Getty Images

The gray whale (Eschrichtius robustus) is divided into two distinct populations that are located in the eastern and western North Pacific Ocean. Commercial whaling severely depleted both populations, but the eastern gray whale population has fared far better than the western population, with approximately 27,000 gray whales living in the eastern Pacific from the coasts of Alaska to those of Mexico. However, the western gray whale, found along East Asia's coasts, has a population of around 300. Population numbers have been gradually increasing over the past few years, encouraging the IUCN to change the designation of the western population from Critically Endangered to endangered.

Still, western gray whales are susceptible to numerous threats. Accidental entanglement in fishing nets has proved to be a serious threat, killing several gray whales off the coasts of Asia. The species is also susceptible to ship strikes and pollution and is especially threatened by offshore oil and gas operations. These operations have become increasingly prevalent near the whales' feeding grounds, potentially exposing the whales to toxins from oil spills as well as disturbing the whales with increased ship traffic and drilling.

of 14

Vaquita - Critically Endangered

a gray vaquita emerging from the water

Paula Olson, NOAA / Wikimedia Commons / CC0 1.0

The vaquita (Phocoena sinus) is a species of porpoise and the smallest known cetacean, reaching a length of about 5 feet and weighing around 65 to 120 pounds. It also has the smallest range of any marine mammal, living only in the northern Gulf of California, and is so elusive that it wasn't discovered by scientists until 1958. Unfortunately, the vaquita population has been dramatically declining from an estimated 567 individuals in 1997 to only 30 individuals in 2016, making it the most endangered marine mammal on earth and causing the IUCN to list it as critically endangered. It is likely that the species will become extinct within the next decade.

By far the biggest threat to the survival of vaquitas is entanglement in gillnets, which kills a significant proportion of the vaquita population every year. Between 1997 and 2008, an estimated 8 percent of the vaquita population was killed each year as a result of entanglement in gillnets, and between 2011 and 2016, this number increased to 40 percent. The Mexican government has recently banned gillnet fishing in the vaquita's habitat, but the efficacy of this ban is not yet clear.

of 14

Narrow-Ridged Finless Porpoise - Endangered

a gray narrow-ridged finless porpoise emerging from the water

Yohkawa / Wikimedia Commons / CC BY-SA 4.0

The narrow-ridged finless porpoise (Neophocaena asiaeorientalis) is the only porpoise without a dorsal fin. It is found in the Yangtze River and off the coasts of East Asia. Unfortunately, because the areas around the porpoise's habitat have become increasingly industrialized and more heavily populated by humans, narrow-ridged finless porpoise population numbers have plummeted by an estimated 50 percent over the past 45 years. Some areas, such as the Korean portion of the Yellow Sea, have seen even sharper population declines of up to 70 percent. The IUCN thus lists the narrow-ridged finless porpoise as endangered.

The species faces a variety of threats to its survival, and one of the biggest is entanglement in fishing gear, especially gillnets, which has resulted in the deaths of thousands of narrow-ridged finless porpoises over the past two decades. Ship strikes have also proved to be a significant danger to the species, and vessel traffic continues to expand in the porpoise's habitat as the area becomes increasingly developed.

The species also suffers from habitat degradation. The increasing presence of shrimp farms along the coasts of East Asia has restricted the range of the porpoise, while sand mining in China and Japan has also destroyed significant portions of the porpoise's habitat. The construction of multiple dams in the Yangtze River has also proved to be a danger to the species, and factories along the river's coast have pumped sewage and industrial waste into the water, posing a serious threat to the porpoises living there.

of 14

Baiji - Critically Endangered (Possibly Extinct)

a gray baiji swimming in the water

Institute of Hydrobiology, Chinese Academy of Sciences / Wikimedia Commons / CC BY-SA 4.0

The baiji (Lipotes vexillifer) is a species of freshwater dolphin so rare that it is likely extinct, which if true, would make it the first dolphin species driven to extinction by humans. The baiji is endemic to the Yangtze River in China, and while the last baiji confirmed to exist by scientists died in 2002, there have been several recent unconfirmed sightings by civilians, leading the IUCN to classify the species as critically endangered (possibly extinct) with the strong possibility of its designation soon being changed to extinct if no individuals can be confirmed to exist by scientists.

The baiji population once numbered in the thousands, and the species was venerated by local fishermen as the "Goddess of the Yangtze," a symbol of peace, protection, and prosperity. However, as the river became increasingly industrialized during the 20th century, the baiji's habitat was significantly reduced. Industrial waste from factories polluted the Yangtze, and the construction of dams restricted the baiji to smaller portions of the river. Furthermore, during the Great Leap Forward from 1958 to 1962, the baiji's status as a goddess was denounced and fishermen were encouraged to hunt the dolphin for its meat and skin, causing further population declines. Even when the baiji was not intentionally caught by fishermen, individuals frequently became entangled in fishing gear intended for other species, and many of the dolphins were killed by collisions with ships. The sharp population decline and probable extinction of the baiji was thus the result of several factors.

of 14

Atlantic Humpback Dolphin - Critically Endangered

a gray Atlantic humpback dolphin emerging from the water

Ednomesor / Wikimedia Commons / CC0 1.0

The Atlantic humpback dolphin (Sousa teuszii) lives off the coast of West Africa, though individuals of the species are rarely seen by humans. While the species was once abundant in West Africa's coastal waters, its population has been sharply declining by more than 80 percent over the past 75 years and is currently estimated to be less than 3,000 individuals, of which only around 50 percent are mature. The IUCN thus lists the species as critically endangered.

The greatest threat to the survival of the species is incidental bycatch by fisheries, which frequently occurs throughout the dolphin's range. The species is also occasionally intentionally targeted by fishers and sold for its meat but is mostly caught by accident. The Atlantic humpback dolphin is also threatened by habitat destruction, especially as a result of port development since an increasing number of ports are being built on the coasts where the dolphins live. Water pollution as a result of coastal development, phosphorite mining, and oil extraction also contributes to the degradation of the dolphin's habitat.

of 14

Hector's Dolphin - Endangered

a gray Hector's dolphin leaping out of the water

Alexander Schnurer / Getty Images

Hector's dolphin (Cephalorhynchus hectori) is the smallest species of dolphin and the only cetacean endemic to New Zealand. The population is believed to have declined by 74 percent since 1970, leaving a current population of only 15,000 individuals. The IUCN has therefore listed the species as endangered.

The largest threat to the survival of the species is entanglement in gillnets, which is responsible for 60 percent of Hector's dolphin deaths. The dolphin is also attracted to trawling vessels, and individuals have been observed approaching the ships and diving into their nets, resulting in potentially fatal entanglement. Furthermore, disease, particularly the parasite Toxoplasma gondii, is the second largest killer of Hector's dolphins after fishing-related deaths. Pollution and habitat degradation may also pose serious threats to the survival of the species.

of 14

Irrawaddy Dolphin - Endangered

a gray Irrawaddy dolphin swimming in the ocean

isuaneye / Getty Images

The Irrawaddy dolphin (Orcaella brevirostris) is unique in that it is able to live in both freshwater and saltwater habitats. The species is fragmented into several subpopulations scattered throughout the coastal waters and rivers of Southeast Asia. A majority of the Irrawaddy dolphin's global population lives in the Bay of Bengal off the coast of Bangladesh, amounting to an estimated 5,800 individuals. The rest of the subpopulations are very small and range from a few dozen to a few hundred individuals. Unfortunately, mortality rates for the species continue to increase, causing the IUCN to list the species as endangered.

Entanglement in gillnets proves to be the biggest threat to the survival of the species, accounting for 66-87 percent of human-caused Irrawaddy dolphin deaths depending on the subpopulation. Habitat degradation is also a serious threat. River populations suffer indirectly from deforestation, which results in increased sedimentation in their river habitats. Habitat loss resulting from the construction of dams is especially concerning along the Mekong River. Gold, gravel, and sand mining as well as noise pollution and contamination from pollutants such as pesticides, industrial waste, and oil pose significant dangers to both ocean and river populations.

of 14

South Asian River Dolphin - Endangered

a gray South Asian river dolphin emerging from the water

Zahangir Alom, Marine Mammal Commission, NOAA / Wikimedia Commons / CC0 1.0

The South Asian river dolphin (Platanista gangetica) is divided into two subspecies, the Ganges river dolphin and the Indus river dolphin. It is found throughout South Asia, primarily in India, Pakistan, Nepal, and Bangladesh in the Indus, Ganges-Brahmaputra-Meghna, and Karnaphuli-Sangu river systems. Although the species was once abundant in these river systems, today the total global population of the South Asian river dolphin is estimated to be less than 5,000 individuals. Furthermore, its geographic range has been dramatically reduced over the past 150 years. The modern range of the Indus river dolphin subspecies is approximately 80 percent smaller than it was in the 1870s. While the Ganges river dolphin subspecies has not seen such dramatic reductions in its range, it has become locally extinct in areas of the Ganges that were once home to significant river dolphin populations, especially in the upper Ganges. The IUCN has thus listed the species as endangered.

The South Asian river dolphin faces a wide variety of threats to its survival. The construction of multiple dams and irrigation barriers on the Ganges and Indus Rivers has resulted in the fragmentation of dolphin populations in these areas and greatly reduced their geographic range. These dams and barriers also degrade the water by increasing sedimentation and disrupt populations of fish and invertebrates that serve as food sources for the dolphins. Furthermore, both subspecies suffer from accidental capture in fishing gear, especially gillnets, and the species is sometimes purposely hunted for its meat and oil, which is used as bait when fishing. Pollution is also a significant threat as industrial waste and pesticides are deposited into the dolphin's habitats. As the areas in which these rivers are located have become more industrialized, the rivers have become increasingly polluted.

of 14

Indian Ocean Humpback Dolphin - Endangered

a gray Indian Ocean humpback dolphin leaping out of the water while a second dolphin swims under the water beside it

Mandy / Wikimedia Commons / CC BY 2.0

The Indian Ocean humpback dolphin (Sousa plumbea) is found in the coastal waters of the western half of the Indian Ocean, stretching from the coasts of South Africa to India. The species was once widely abundant throughout the Indian Ocean, but population numbers have quickly declined. The global population is estimated to be in the low tens of thousands with a predicted population decline of 50 percent over the next 75 years. Even in the early 2000s, the Indian Ocean humpback dolphin was one of the most commonly sighted cetaceans in much of the Arabian Gulf, and large groups of 40 to 100 dolphins were frequently seen swimming together. Today, however, there are only a few small, disconnected populations of fewer than 100 individuals in the same region. The IUCN has therefore listed the species as endangered.

Because the species tends to stay close to shore in shallow waters, its habitat coincides with some of the waters most heavily utilized by humans, posing severe threats to its survival. Fishing is extremely common in the dolphin's range, and the Indian Ocean humpback dolphin is thus at severe risk of being incidentally captured as bycatch, especially in gillnets. Habitat destruction is also a serious threat since ports and harbors are increasingly built near the dolphin's habitats. Pollution is an additional danger to the species as human waste, chemicals such as pesticides, and industrial waste are frequently released from major urban centers into the coastal waters inhabited by the dolphins.

of 14

Amazon River Dolphin - Endangered

a pink Amazon river dolphin emerging from the water

aniroot / Getty Images

The Amazon river dolphin (Inia geoffrensis) is found throughout the Amazon and Orinoco river basins in South America. The species is notable for being the largest river dolphin on earth, with males weighing up to 450 pounds and growing up to 9.2 feet long, as well as for becoming pink in color as it matures, earning it the nickname "pink river dolphin." Despite being the most widespread species of river dolphin, Amazon river dolphins have been declining in number throughout their range. While data on population numbers is limited, in the areas where data is available, population numbers look bleak. In Mamirauá Reserve in Brazil for example, populations have plummeted by 70.4 percent over the past 22 years. The IUCN therefore lists the species as endangered.

The Amazon river dolphin faces a wide range of threats. Beginning in 2000, the dolphin has been increasingly targeted and killed by fisheries who then use pieces of its meat as bait to catch a kind of catfish known as Piracatinga. The deliberate killing of Amazon river dolphins for bait is the biggest threat to the survival of the species, but incidental capture as bycatch is also a serious problem. In addition to threats from fisheries, the species also suffers from habitat degradation as a result of mining operations and dam construction, a threat that may prove to be even more serious in the future as dozens of dams that have not yet been built are being planned along the Amazon River.

Pollution is also a serious danger to the dolphins. Scientists have observed high levels of toxins such as mercury and pesticides in samples of Amazon river dolphin milk, indicating that not only has the dolphin's habitat become contaminated with these toxins, but also that the dolphins themselves have absorbed these pollutants into their bodies.

View Article Sources
  1. Cooke, J.G. "Eubaleaena Glacialis." The IUCN Red List of Threatened Species, 2020, doi:10.2305/IUCN.UK.2020-2.RLTS.T41712A178589687.en

  2. Cooke, J.G., and P.J. Clapham. "Eubalaena Japonica." The IUCN Red List of Threatened Species, 2018, doi:10.2305/IUCN.UK.2018-1.RLTS.T41711A50380694.en

  3. Cooke, J.G. "Balaenoptera Borealis." The IUCN Red List of Threatened Species, 2018, doi:10.2305/IUCN.UK.2018-2.RLTS.T2475A130482064.en

  4. Cooke, J.G. "Balaenoptera Musculus." The IUCN Red List of Threatened Species, 2018, doi:10.2305/IUCN.UK.2018-2.RLTS.T2477A156923585.en

  5. Cooke, J.G., et al. "Eschrichtius Robustus (Western Subpopulation)." The IUCN Red List of Threatened Species. 2018, doi:10.2305/IUCN.UK.2018-2.RLTS.T8099A50345475.en

  6. Rojas-Bracho, L., and B.L. Taylor. "Phocoena Sinus." The IUCN Red List of Threatened Species, 2017, doi:10.2305/IUCN.UK.2017-2.RLTS.T17028A50370296.en

  7. Wang, J.Y., and R. Reeves. "Neophocaena Asiaeorientalis." The IUCN Red List of Threatened Species, 2017, doi:10.2305/IUCN.UK.2017-3.RLTS.T41754A50381766.en

  8. Smith, B.D., et al. "Lipotes Vexillifer." The IUCN Red List of Threatened Species, 2017, doi:10.2305/IUCN.UK.2017-3.RLTS.T12119A50362206.en

  9. Collins, T., et al. "Sousa Teuszii." The IUCN Red List of Threatened Species, 2017, doi:10.2305/IUCN.UK.2017-3.RLTS.T20425A50372734.en

  10. Reeves, R.R., et al. "Cephalorhynchus Hectori." The IUCN Red List of Threatened Species, 2013, doi:10.2305/IUCN.UK.2013-1.RLTS.T4162A44199757.en

  11. Minton, G., et al. "Orcaella Brevirostris." The IUCN Red List of Threatened Species, 2017, doi:10.2305/IUCN.UK.2017-3.RLTS.T15419A50367860.en

  12. Braulik, G.T., and B.D. Smith. "Platanista Gangetica." The IUCN Red List of Threatened Species, 2019, doi:10.2305/IUCN.UK.2017-3.RLTS.T41758A151913336.en

  13. Braulik, G.T., et al. "Sousa Plumbea." The IUCN Red List of Threatened Species, 2017, doi:10.2305/IUCN.UK.2017-3.RLTS.T82031633A82031644.en

  14. Da Silva, V., et al. "Inia Geoffrensis." The IUCN Red List of Threatened Species, 2018, doi:10.2305/IUCN.UK.2018-2.RLTS.T10831A50358152.en