The ocean seems to be seen as an endless resource by humanity. Due to its immense vastness, depth, and uncharted regions, many people think it’s impervious to overexploitation. But in reality, the populations of many species are declining at an unsustainable rate, and an increasing number of species of marine life, including sharks, salmon, seabirds, sea turtles, manatees, and dugongs, to mention a few, are being listed as endangered. It may even surprise you that several dolphin species worldwide are also threatened. But are there dolphin species that are already extinct?
Being less apparent than creatures on land makes it difficult to see marine life’s risks. However, aquatic creatures are sadly just as susceptible—if not more—to issues like habitat loss and overfishing. Animals that have spent millions of years evolving are vanishing from habitats where they once thrived. Dolphins are among the most adored creatures on the planet, inspiring countless brands featuring their contagious grin, including films, books, television documentaries, and apparel. But one dolphin species’ future is anything but bright, as their populations were driven to extinction by none other than humans. This article will look into the first dolphin species to go extinct and other interesting facts.
Baiji (Yangtze River Dolphin)
An endemic freshwater species known as the baiji, or Yangtze River dolphin, was deemed extinct in 2008, making it the first dolphin species humans drove to extinction. The loss also marks the first global extinction of megafauna—any animal weighing more than 200 pounds (100 kilograms)—since the demise of the Caribbean monk seal (Monachus tropicalis).
The baiji’s body was stocky, and its flippers were large and rounded. The head, small in size, featured a noticeable melon, a very long, narrow beak with a slight upturn at the tip, and a lengthy mouth line. Compared to other dolphin species, the eyes of the baiji were small and situated higher on the head. More than halfway back, the dorsal fin was tiny, trapezoidal, and had a broad base.
Baijis typically had a bluish-grey color on their back and a greyish-white color on their lower body. Mature males were about 2.3 meters (7.5 ft) long, females 2.5 meters (8 ft 2 in), and the longest specimen was 2.7 meters (8 ft 10 in) long. The species weighed between 135-230 kilograms (298-507 lb) and had an estimated 24-year lifespan in the wild.
Only the Yangtze River in China was home to the baiji, and this river is Asia’s largest and the third-longest river in the world. Most baijis resided along the middle and lower portions of the Yangtze River and two sizable connecting lakes called Dongting and Poyang.
Baijis were frequently spotted around sandbars, which form where tributaries reach the main river and sediment is dumped. These sandbars provide nutrient-rich, fish-attracting eddies in the water. These environments are preferred by baijis and fishermen equally for catching fish.
The diet of a baiji consisted primarily, if not entirely, of fish, including both bottom and surface-feeders. Baijis consumed a wide range of tiny fish, such as carp, yellow catfish, and copper fish. These quick dolphins may snag little fish and consume them whole. They searched for food by probing muddy bottoms with their long beaks, and their quick dives only lasted 10 to 20 seconds. Despite having poor eyesight, baijis used their evolved echolocation abilities to obtain food. These critters hunted for food in the shallow water adjacent to sandbanks or at the river’s tributary mouths.
Throughout the late 20th century, the baiji population fell rapidly; only 13 species were counted between 1997 and 1999, compared to an estimated 400 in the 1980s. The last confirmed baiji reports are from a pregnant baiji discovered stranded in Zhenjiang in November 2001 and one seen in the Tongling River region in May 2002.
In the main Yangtze channel, a comprehensive six-week multi-vessel visual and auditory investigation in 2006 that spanned the full historical range of the baiji failed to uncover any proof that the species was still extant. In 2008, additional interview studies in 27 Yangtze fishing communities from Yichang to Shanghai similarly discovered zero evidence of any surviving baiji species.
Even if there are other baijis that scientists have not discovered, the Yangtze region’s ecology, which is home to about 10% of the world’s population, is still degrading, meaning the species has no chance of even short-term survival as a viable population.
What are the Factors that Led to the Extinction of the Baijis?
Sadly, all of the causes of the endangerment or extinction of this species are human-made. Most fatalities were caused by indiscriminate fishing, such as bycatch, which caught and killed many individuals. The use of harmful fishing methods, including gill nets, rolling hooks, and electrical stunning—which were not even intended to harm dolphins—were also likely to have pushed the species to extinction.
But ultimately, pollution threats to dolphins come from chemical and noise pollution. Dolphins are particularly sensitive to underwater noise from boat traffic, sonar, and underwater construction because they rely on pulsed and tonal noises for communication, navigation, and finding food, just like whales do. Unfortunately, as the river became a noisier place to dwell, the baiji’s echolocation abilities to communicate, navigate, escape danger, and find food grew more difficult. Since they relied so largely on sound to communicate because they were virtually blind, losing that ability could have had catastrophic consequences in their ability to find food and engage in other crucial social behaviors.
Additionally, large populations of dolphins may contract diseases brought on by chemical or oil spills in the water, which frequently have negative repercussions, such as mortality or failure to reproduce. Life must have been extremely challenging for the remaining baijis, and the Chinese government’s acceptance of the Three-Gorges Dam’s construction must have been the icing on the cake. This massive hydroelectric dam, whose construction began in 1994 and took several years, damaged wildlife habitats, killed off native species, and caused extensive environmental harm to the Yangtze River.
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