Cetaceans are one of the most well-known groups of marine animals. There are around 89 living species in this group including whales, porpoises, and dolphins. Cetaceans are marine mammals that are widely distributed, finned, and carnivorous in nature. Unfortunately, many species of cetaceans are in great danger of extinction due to human activities and interference in their environment. Many have also been hunted to near extinction. The loss of these cetaceans means damage to the ecological balance of marine ecosystems. Since most of the cetacean species are apex predators in their habitat, removal of the species creates an ecological imbalance. Here is a list of the endangered species of cetaceans as mentioned in the IUCN Red List of Threatened Species. There are seven species listed as endangered and two species listed as critically endangered.
9. Sei Whale
The Balaenoptera borealis is one of the largest extant species of whales. The species prefers to inhabit the open sea and has widespread distribution. However, it avoids the tropical and polar waters. The sei whales consume krill, zooplankton, and copepods. Today, the species has been labeled as endangered by the IUCN. The population of the whale has greatly reduced over the past century. Commercial whaling activities during the late 19th and early 20th centuries led to the loss of thousands of whales. The sei whale currently receives international protection.
8. Blue Whale
The Balaenoptera musculus, the largest mammal in the world, is, unfortunately, an endangered species. It can have a length of up to 98 ft and weigh about 190 short tons. In the past, blue whales had a widespread distribution and occurred in all oceans of the world. However, these mammals were nearly hunted to extinction by humans in the 20th century. According to a 1996 report, only 5,000 to 12,000 blue whales survived in the world’s oceans. According to an estimate by the IUCN, there are only 10,000 to 25,000 blue whales living today. Bans on hunting in most parts of the world have helped stabilize the blue whale population to some extent.
7. Fin Whale
The Balaenoptera physalus is the world’s second-largest mammal. It can attain lengths of up to 89.6 ft. This species inhabits all the major oceans of the world. It can survive in a wide variety of marine habitats ranging from the tropical to the polar waters. The fin whale was also heavily hunted throughout the 20th century. Sadly, some countries continue to permit the hunting of these whales even today. It will thus be difficult to save the species if a global ban on its hunting is not implemented.
6. Hector's Dolphin
The Cephalorhynchus hectori, one of the smallest cetaceans, is endemic to New Zealand. Only around 55 individuals of this species are alive today. Irresponsible fishing practices pose the greatest threat to the survival of this species. Over the years, thousands of these dolphins have died by entrapment in trawl fisheries and bottom-set gillnets. About 110 to 150 dolphins are caught as bycatch in New Zealand each year. The data is frightening indeed given the extremely low population of Hector's dolphin. Other threats to the species include marine mining, disease, and tourism activities. Although several steps have been taken by the New Zealand government to protect the species, the situation is still quite grim.
5. North Atlantic Right Whale
The Eubalaena glacialis is another species of endangered cetacean. For decades, this whale species was hunted indiscriminately. Several factors like their docile nature, high blubber content (which yielded more oil), preference to stay near the coast, and relatively slow movements, made them an easy and desirable target of the whalers. Today, the North Atlantic right whale is the most endangered whale in the world. Only about 400 members of the species remain. Their habitat is now restricted to the western part of the North Atlantic Ocean. Heavy shipping traffic in the area further aggravates the situation. Here, they are highly susceptible to entanglement in fishing gear and vessel collisions. Thus, little hope remains for this species and scientists even believed that the species is functionally extinct.
4. North Pacific Right Whale
The Eubalaena japonica is a massive baleen whale that is also enlisted as endangered on the IUCN Red List. The total population of the North Pacific Right Whale is estimated to be in the low hundreds. Commercial whaling is the biggest threat to the survival of the species. Although whaling has been banned in most parts of the range of this species, cases of illegal whaling activities have been recorded. Between 1962 and 1968, illegal Soviet whaling killed hundreds of whales in the Bering Sea, Sea Okhotsk, and the Gulf of Alaska.
3. South Asian River Dolphin
The Platanista gangetica is an endangered species of freshwater river dolphin that is found in the Indian subcontinent. There are two subspecies of this dolphin. The Ganges river dolphin is found in the Ganges and Brahmaputra river system. The Indus river dolphin occurs in Pakistan’s Indus River. Death as bycatch, pollution of the rivers, construction of dams, and other forms of anthropological pressures in their environment have pushed these dolphins to the brink of extinction.
The Baiji (Lipotes vexillifer) is a freshwater dolphin endemic to China and found principally in the Yangtze River. There were estimated to be 6,000 Baiji in 1950. Over the next several decades, the Baiji was listed as critically endangered by the ICUN and considered to be the most endangered cetacean in the world. By 1997, only 13 individuals were left. The last sighting of the Baiji was in 2004 and the species is now thought to be extinct.
With the possible extinction of the Baiji, the Vaquita has earned the title of the world's most endangered cetacean. A porpoise endemic to the Gulf of California, the Vaquita has been listed as critically endangered since 1996. As of March 2018, only 12 to 15 individuals were thought to remain and the species is expected to go extinct if drastic measures are not taken. The plight of the Vaquita is being featured in the documentary "Sea of Shadows." Bycatch and poaching are thought to be the leading contributors to the decline of the Vaquita.