Threatened species of Lipotes vexillifer
Name(s):
Threatened species of Baiji
Endangered species of Chinese river dolphin
Nature
Lipotes vexillifer is probably the most endangered of all cetaceans. The total population is estimated at between 60 and 250 animals and only 2 in captivity.. It is the rarest whale in the world. In the past 15 years, the baiji population is reported to have declined from about 400 animals in 1979-80 to 200 or so in 1986 and to perhaps 150 or fewer in 1993. Despite disagreements over validity of estimates, an observed constriction in the baiji's range and dramatically low rates of sightings during recent Chinese expeditions have lent credence to concern that the baiji population is small and declining. 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 hooking 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. China began providing legal protection in 1975. The endangerment proceeds from habitat displacement, as the Yangtze River steadily becomes less livable for both prey items and predators. Building a dam on the Yangtze River will impact the animals who depend on it's current state for survival.
Background
Lipotes vexillifer is found in China in the mouth of the Chang Jiang (Yangtze) up to about 1900 km up the river, as well as in the middle and lower regions of the Quintangjiang River. The population density is equivalent to 1 dolphin every 2 miles. Lipotes vexillifer's diet consists of mainly, if not entirely, fish. They use their long beaks to probe muddy bottoms in the shallow water near sandbanks or close to the mouth of tributaries for food. Their dives are short, lasting only 10- 20 seconds. Baiji have poor eyesight but use a highly developed echolocation faculty to find food.
Many programs are also being established to breed Lipotes vexillifer in captivity. Some captive breeding methods include artificial insemination and exogenous induction of ovulation. Accordingly, from 1-4 June, 1993, a workshop was convened at Nanjing Normal University, Nanjing, China, to again review the available information on baiji and to conduct a Population and Habitat Viability Assessment Workshop on the species. The Workshop was collaboratively organized by the Mammalogical Society of China, the IUCN Species Survival Commission's (SSC) Cetacean Specialist Group, and the IUCN/SSC Captive Breeding Specialist Group.
Incidence
The baiji is at a very high risk of extinction in the next 25 to 100 years.
Type
(S) Suspect problems