FRESHWATER DOLPHINS AND PORPOISES IN CHINA
For millions of years river dolphins have inhabited the Yangtze. The first are believed to have migrated up the Yangtze 20 million years ago. Baijis (Scientific name: Lipotes vexillifer) are a freshwater dolphin species found in China. They are the rarest and most endangered of all whale, porpoise of dolphin species. They are now regarded as functionally extinct. They live on a 1,000-mile stretch of the Yangtze river between the mouth of the river and the Three Gorges.
Baiji are important culturally in China and have long been protected by custom. They have traditionally been viewed by some as "the Goddess of Chang Jiang" and are a good omen to any fisherman who spots one. Chang Jiang is the Chinese name of the Yangtze. In the past, the fat of accidentally killed individuals was used for medicinal purposes and the flesh consumed. The current plight of baiji — designated a national treasure "of the first order" by China — has raised awareness of the need for conservation of river systems worldwide.
There is also a species of river porpoise: the finless porpoise. In 1993 2,700 lived in the Yangtze. Less than 1,000 live there now according to an expedition in 2006. So they don't go the same way as the baiji and colony of 30 of them has been established in nature preserve, far from the polluted river. The hope is that they will reproduce.
Websites and Resources: Britain-based Whale and Dolphin Conservation Society uk.whales.org ; Animal Diversity Web (ADW) animaldiversity.org; National Oceanic and Atmospheric Administration (NOAA) noaa.gov; Fishbase fishbase.se; Encyclopedia of Life eol.org; Smithsonian Oceans Portal ocean.si.edu/ocean-life-ecosystems ; Monterey Bay Aquarium montereybayaquarium.org ; MarineBio marinebio.org/oceans/creatures
Baijis (Yangtze River Dolphins)
Baiji have traditionally been found in China from the mouth of the Chang Jiang (Yangtze) to a point about 1,900 kilometers (1,200 miles) up the river, as well as in the middle and lower regions of the Quintangjiang River and in the Dongting and Poyang lakes. They prefer to stay near large eddies that form next to sandbars and have been observed in lakes, ponds, rivers, streams as well as estuaries and areas adjacent to rivers and other water bodies. [Source: Allison Poor and Sarah Grigg, Animal Diversity Web (ADW) /=]
Baijis, also known as white flag dolphins or Yangtze river dolphins have a long snout and small eyes and have white sides and a pale blue grayish back. They feed primarily on fish, which they locate with sonar since they are nearly blind. By some reckonings the Yangtze river dolphin is considered to be an Irrawaddy dolphin. Baijis can live to be 25 to 30 years of age. One wild-caught one was estimated to be 24 years of age. They stay under water for an average of 20 seconds and can dive for up to two minutes. They are usually found in pairs or social units of 10 or so members. Some scientists regard them as a subspecies of Irrawaddy fresh water dolphin.
Baiji weigh between 42 to 167 kilograms (93 and 370 pounds) and reach a length of 2.5 meters (8.2 feet). Sexual Dimorphism (differences between males and females) exists: Females are larger than males. They range from 1.85 to 2.5 meters (6 to 8.2 feet) in length and weigh 64 to 167 kilograms (141 to 370 pounds) , while males range from 1.4 to 2.2 meters (4.6 to 7.2 feet) weigh between 42 and 125 kilograms (93 and 276 pounds). [Source: Allison Poor and Sarah Grigg, Animal Diversity Web (ADW) /=]
Baiji, like other dolphins, have streamlined, fusiform bodies. They have rounded flippers and long, beaklike, upturned snouts, which are completely hairless. Their small but functional eyes sit high on their heads, and their blowholes are elliptical and oriented longitudinally. Baiji are pale blue-grey dorsally and white ventrally. They have 30-36 teeth per side of both the upper and lower jaws.
Baij are endothermic (use their metabolism to generate heat and regulate body temperature independent of the temperatures around them). They have no fore-stomachs but their main stomachs consist of three chambers, and they lack ceca. The skulls of these dolphins lack maxillary crests, and the palatal portions of the maxillae contact one another. /=\
Baiji Behavior, Perception and Feeding
Baiji are diurnal (active mainly during the daytime), motile (move around as opposed to being stationary), and social (associates with others of its species; forms social groups). They communicate with sound and sense using touch, sound, echolocation. (emitting sound waves and sensing their reflections to determine the location of objects) and chemicals usually detected by smell. [Source: Allison Poor and Sarah Grigg, Animal Diversity Web (ADW) /=]
Due to shyness and fact they are so rarely seen, much of the behavior of baiji is poorly understood, They have traditionally been found in pairs, which sometimes joined with other pairs to form larger social units of about 10 individuals. Most of their time is spent in the vicinity of large eddies, shallow water near sandbanks or close to the mouth of tributaries of the rivers, where they search for fish during the day. At night they rest in areas of slow current. The population density in the Quintangjiang was estimated in 1978 and 1980 at one Baiji every 4 kilometers.
The baiji diet consists mainly, but not entirely, of fish. They use their long beaks to probe muddy bottoms for food. Their dives are short, lasting only 10-20 seconds. Baiji have poor eyesight but use a highly developed echolocation ability to find food.. In the turbid, muddy waters of the Yangtze, vision is is of little help so baiji rely on echolocation to navigate and find food. They communicate with one another using whistles and other acoustic signals.
Baiji Mating, Reproduction and Offspring
Baiji are viviparous, meaning they give birth to live young that developed in the body of the mother, and engage in seasonal breeding. Female baiji breed once every two years. The mating season peaks twice a year, in spring and in autumn. The gestation period ranges from six to 12 months. Females and males reach sexual maturity at three to eight years. .[Source: Allison Poor and Sarah Grigg, Animal Diversity Web (ADW) /=]
Little is known about the reproductive activities of baiji. Ovulation in females is periodic and sperm density in males varies seasonally. Females give birth to one 80 centimeter- (2,2-foot) -long calf. During the pre-fertilization, pre-birth, and pre-weaning stages provisioning and protecting is done by females.
Mothers carry their calves close to the side of their bodies while swimming, diving, and coming up to breathe. It is unknown how long they nurse their young, and whether there is any association between mother and offspring after the young are weaned
Endangered (Maybe Extinct) Baiji
Baiji are one of the most endangered animals on Earth. They are classified as “Critically Endangered” on International Union for Conservation of Nature (IUCN) Red List. The Endangered; Convention on International Trade in Endangered Species (CITES) places them in Appendix I, which lists species that are the most endangered among CITES-listed animals and plants.
The baiji is now regarded as "functionally" extinct. During November and December 2006, an international research team made up of by 30 scientists conducted an intensive six-week multi-vessel visual and acoustic survey covering the entire historical range of the Yangtze river dolphin in the main Yangtze channel between Yichang and Shanghai. The team covered 1,700 kilometers (1,050 miles )of the Yangtze, using sophisticated viewing equipment and ultra-sensitive microphones failed to locate a single dolphin. August Pfluger, a Swiss researcher and leader of the survey told the Washington Post, "It is possible that there are two or three that we missed somehow but functionally they are extinct. It is finished. This is very, very, sad."If they are extinct they are first species of whale dolphin, or porpoise to be made extinct by man.
As of the 1990s only 100 or so baijis remained in the wild. Their number had declined from 6,000 in the 1950s to 400 in the 1980s to 150 in 1993 to 100 in 1995. At that point their future didn't look good: they live in one of the world's most densely populated areas and had a large part of their natural habitat gobbled up by the Three Gorges Dam project. Experts estimated that species would probably be extinct within 10 to 15 years.
A survey of baiji in 1997 found 13 of them. A four boat survey in 1999 counted four. A pair was seen in Hongpu Lake in July 2005. A sighting was recorded in the summer of 2006. A Chinese man videotaped a baiji swimming in the Yangtze River in the summer of 2007. The man was quoted Reuters as saying, "I never saw such a big thing in the water before so filmed it." He said he was about one kilometer away and it jumped several times. The last one captivity died in 2002.
Threats to Baiji
Baiji have mainly been done in the last two or three decades by sewage and pollution dumped into the Yangtze and noise created by ship propellers which disrupt their sonar-based sensory system, making it difficult for them to find food and navigate through the river's murky waters. They have also been trapped in nets, hurt by boats dragging the river bottom and injured by motor boats. The fish they feed have been overfished with large nets. Many baiji have been snagged on rolling hooks, illegal fishing devices consisting of braided lines with a hundred or more hooks hanging off them.
According to Animal Diversity Web: There are three major factors that threaten baiji survival: dams and floodgates that block fish migration in the river's tributaries and lakes, fisheries accidentally killing dolphins, and boat propellers. Population numbers also declined through hunting and development of irrigation facilities. The heavy pollution and underwater noise characteristic of the Yangtze also affects the Baiji. These stresses, as well as lack of food, can inhibit reproduction. /=\
Efforts to Save Baiji in China
China began providing legal protection in 1975. Programs are being established to breed Baiji in captivity, though no one has yet succeeded at housing wild baiji for long. In 1992 an oxbow jutting off from the main Yangtze river was set aside as a reserve where baiji could be relocated and allowed to live under semi-natural conditions. In the face of ongoing degradation of the Yangtze river, this "ex-situ" conservation strategy may be the species' only hope for survival.
An effort is being made to set up a sanctuary for the dolphins in a 13-mile-long oxbow lake, 150 miles upriver from Wuhan. For several months a year, the lake floods and is replenished with fish from the Yangtze River. So far this effort has been less than successful. The first dolphin placed in the sanctuary died after it got tangled in a net that separated the reserve from the river. After this construction began on a concrete barrier that didn't endanger the dolphins but allowed water and fish to flow in.
The leader of the save-the-baiji movement is Wang Ding, the director of river dolphin research at China's Institute of Hydrobiology and leader of the Wuhan Baiji Conversation Foundation. To save the dolphins and make the public aware of their plight, statues of the animals have been erected and a local brewery even introduced Baijitun beer.
Divisions over how best to conserve rare animals partly contributed to the demise of the baiji because foreign and Chinese zoologists were unable to agree on whether it should be taken to a reserve or looked after better in its natural environment. Reserves were set up for the baiji and laws and regulations were enacted to help them. But these reserves existed largely in name only and the laws were not enforced.
Image Sources: Wikimedia Commons, NOAA
Text Sources: Animal Diversity Web (ADW) animaldiversity.org; National Oceanic and Atmospheric Administration (NOAA) noaa.gov; Wikipedia, National Geographic, Live Science, BBC, Smithsonian, New York Times, Washington Post, Los Angeles Times, The New Yorker, Reuters, Associated Press, Lonely Planet Guides and various books and other publications.
Last Updated June 2023