Whales, magnificent marine mammals, are not immune to extinction. Throughout history, various whale species and other large marine mammals have vanished, highlighting the profound impact of human activities and environmental shifts.
Whale Species Lost to History
While the fossil record reveals numerous ancient whale extinctions, recent history also documents the disappearance of specific whale populations and closely related marine mammals. The Atlantic Gray Whale (Eschrichtius robustus) is one example. This population, once found along the coasts of Iceland, Europe, and North America, was hunted to extinction by the 18th century. Though Pacific Gray Whale populations still exist, the Atlantic population represents a regional loss.
Steller’s sea cow (Hydrodamalis gigas) is another well-documented marine mammal extinction. These enormous creatures, related to manatees and dugongs, grew up to 10 meters long and weighed up to 11 tonnes. Discovered in 1741 in the sub-Arctic waters around the Commander Islands, they were hunted to extinction within just 27 years by 1768. Their social behavior, kelp-based diet in shallow waters, and thick blubber made them vulnerable to human hunters.
The Japanese sea lion (Zalophus japonicus), a pinniped, also vanished in recent history. These animals inhabited the western North Pacific, including coastal areas of Japan and the Korean Peninsula. Commercial hunting in the 1900s severely depleted their numbers, leading to their extinction by the 1970s.
Why Whales Vanished
The primary factor driving the extinction of many whale populations and large marine mammals was commercial whaling. Industrial-scale whaling, beginning in the 17th century and escalating dramatically with 19th and 20th-century technological advancements, targeted whales for their oil, meat, and blubber. Steam-powered vessels and harpoon cannons enabled whalers to hunt faster species, leading to catastrophic declines. Between 1900 and 1999, an estimated 2.9 million whales were killed, with some populations, like the Atlantic gray whale, vanishing entirely.
Beyond direct hunting, habitat destruction and degradation also played a role in the demise of some species. The Japanese sea lion, for example, suffered from overhunting and habitat loss, with submarine warfare during World War II believed to have further contributed to the destruction of their natural environment. While Steller’s sea cow was primarily a victim of direct overharvesting, their reliance on shallow kelp beds for food made them susceptible to localized environmental changes if their food source was impacted.
Climate shifts, particularly during past glacial cycles, also contributed to the fragmentation and decline of some populations over long periods. For Steller’s sea cow, genetic evidence suggests that their population was already fragmented and reduced by the time of their discovery, likely due to past changes in sea levels and temperatures that reduced suitable habitat. These environmental changes, combined with human pressures, pushed already vulnerable populations beyond recovery.
Whales on the Edge
Despite past extinctions, many whale species today face ongoing threats, placing them on the brink of disappearance. The North Atlantic Right Whale (Eubalaena glacialis) is one of the most critically endangered large whale species, with approximately 360 to 370 individuals remaining, including fewer than 70 reproductively active females. Their population has been in decline since 2010 due to high levels of human-caused mortality. The primary dangers they face include entanglement in fishing gear and collisions with vessels. Over 85 percent of North Atlantic Right Whales have experienced entanglement at least once, which can lead to severe injuries, infections, and mortality.
The vaquita, the world’s smallest porpoise, also faces extinction, found only in a small area of Mexico’s Gulf of California. With an estimated population of only around 10 individuals as of 2024, the vaquita is considered the most endangered cetacean globally. Their drastic decline is almost entirely attributed to entanglement in illegal gillnets, particularly those set for the totoaba fish, whose swim bladder is highly valued in illegal trade. The vaquita’s restricted habitat makes it vulnerable to these ongoing threats, with accidental trapping causing them to drown.
Safeguarding Whale Futures
Protecting remaining whale populations involves a multifaceted approach, encompassing international agreements and on-the-ground conservation efforts. The International Whaling Commission (IWC), established in 1946, implemented a moratorium on commercial whaling in 1986, which has been instrumental in allowing many whale populations to begin recovering. This global body sets catch limits, designates protected areas, and regulates whaling practices.
The establishment of protected marine areas plays a significant role in safeguarding whale habitats. These areas, which can include marine national parks or sanctuaries, provide protection for important feeding, breeding, and socializing grounds. While only about 600 of the 20,000 global marine protected areas specifically protect whale and dolphin habitats, efforts are ongoing to expand and connect these areas, particularly for migratory species.
Reducing bycatch, the accidental capture of non-target species, is another critical conservation strategy. For species like the vaquita, implementing and enforcing bans on gillnet fishing and promoting alternative, safer fishing gear are paramount. Initiatives also focus on mitigating the impact of ship strikes through measures like adjusting shipping lanes and reducing vessel speeds in whale migration corridors. Public awareness campaigns further support these efforts by educating people about responsible marine mammal observation and the importance of conservation.