Animal Info - Baiji

(Other Names: 白暨豚, Changjiang Dolphin, Chinese Lake Dolphin, Chinesischer Flussdelphin, Dauphin Fluviatile de Chine, Delfín de China, Pei Ch'i, White-fin Dolphin, White-flag Dolphin, Yangtze or Yangzi River Dolphin)

Lipotes vexillifer

Status: Critically Endangered


Contents

1. Profile (Picture)
2. Tidbits
3. Status and Trends (IUCN Status, Countries Where Currently Found, Population Estimates, History of Distribution, Threats and Reasons for Decline)
4. Data on Biology and Ecology (Size and Weight, Habitat, Age to Maturity, Gestation Period, Birth Season, Birth Rate, Maximum Age, Diet, Behavior, Social Organization, Density and Range)
5. References


Profile

Pictures: Baiji #1 (7 Kb JPEG) (Cetacea); Baiji #2 (68 Kb JPEG) (Terrambiente.org)  

The baiji is a graceful animal, with a long, narrow and slightly upturned beak and a flexible neck. As opposed to some other freshwater dolphins, like the Indus River dolphin, its eyes are functional, although greatly reduced. Its coloration is bluish-gray to gray above and white to ashy-white below. It weighs 135 - 230 kg (300 - 510 lb) and measures as much as 2.5 m (8.2') in length. 

The baiji only occurs in freshwater rivers and lakes. It favors large eddy counter-currents such as are found below meanders; channel convergences; and areas in a river with structure, such as sandbars. In the Yangtze River, the baiji generally lives in the deeper sections, swimming to shallow water only to catch small fish. Any available species of small (less than 6.5 cm (2.5") in width) freshwater fish is eaten.  Feeding activity is primarily diurnal

A group may congregate in the quiet area of an eddy for 5 - 6 hours. At night the baiji often rests in areas of very slow current. Several underwater acoustic signals are apparently used for communication and echolocation. Baijis generally live in small groups of 3 - 4 animals, which may come together to make up a larger social unit of 9 - 16 dolphins. 

The distribution of the baiji originally included not only the lower and middle reaches of the Yangtze River down to the river’s mouth, but also the Qiantang and Fuchun Rivers and Dongting and Poyang Lakes.  It no longer occurs in the lakes or branches of the Yangtze but only in the mainstem, and the extent of its distribution is significantly reduced. The baiji is considered the most endangered cetacean, and its prospects for survival are extremely doubtful. 

Deaths from entanglement in or electrocution by fishing gear, collisions with vessels, blasting for channel maintenance, and illegal harvesting of the baiji are at least partially responsible for the decline of its range and abundance. In addition, the damming of tributaries, drainage for land "reclamation," dredging, depletion of the baiji's prey by over-fishing, and noise and congestion caused by vessel traffic in the river have substantially degraded the Yangtze's environment. The Three Gorges Dam will produce further stress on the baiji population by altering the Yangtze's hydrological regime. The baiji generally occurs in large eddy counter-currents which are expected to be eliminated for approximately 200 km (120 mi) downstream by the water released below the dam. 


Tidbits

*** The baiji is one of the world's rarest mammals.

*** In the past, the baiji had been protected by custom, since the Chinese considered it to be an incarnation of a drowned princess (Burton & Pearson 1987). It also has a nickname in China - "Giant Panda of the Yangtze River" - that may reflect the general affection for this aquatic mammal (Tan 1996).

*** In one area where the baiji is most common (Anhui Province) a council has been set up called the ‘Lipotes vexillifer Conservation Association.' The association is to spread information about the baiji, especially among fishermen along the Yangtze River. An increased awareness of the baiji may have accounted for the rescue of several animals which had been hit by propellers. (Klinowska 1991)


Status and Trends

IUCN Status:

Countries Where the Baiji Is Currently Found:

2006: Occurs in China (Yangtze River) (IUCN 2006).

Population Estimates:

[Note: Figures given are for wild populations only.]

History of Distribution:

Currently, the baiji is endemic to the Yangtze River of China (See Figure 1 (126 Kb PDF) (IUCN 2006)). The baiji also occurred historically in Dongting and Poyang Lakes, both appended water bodies of the Yangtze, but apparently it is no longer found in either lake. The baiji’s upstream limit in the Yangtze has changed from the Three Gorges area - approximately 35 km (22 mi) above Gezhouba Dam near Yichang - in the 1940's to approximately 170 km (105 mi) below the dam site near Jingzhou in the 1990's. This dolphin was once observed as far downstream as the Yangtze River mouth near Shanghai, but it is now rare below Nanjing. No baiji were found downstream of Jiangyin, located 256 km (160 mi) upstream of the mouth, during surveys in 1997 - 99. During the most recent surveys the baiji has been found mainly in several segments of the Yangtze between Tongling and Dongting Lake, such as the Tongling section, the Poyang Lake mouth area, and the Honghu section. (IUCN 2006) (See Figure 1 showing the Yangtze River and locations used to describe the distribution of the baiji.)

Distribution Map #1S (1980's) (24 Kb JPEG) (WCMC/CMS) (smaller map)
Distribution Map #1L (1980's) (71 Kb JPEG) (WCMC/CMS) (larger map)

Threats and Reasons for Decline:

Deaths from entanglement in fishing gear (especially bottom-set, snagging longlines called "rolling hooks"), electrocution from electric fishing, collisions with vessels, underwater blasting for channel maintenance, and illegal hunting of the baiji for its meat and for its body parts (used in traditional medicines) are at least partially responsible for the declines in baiji range and abundance. In addition, the damming of tributaries, drainage for land "reclamation," dredging, depletion of the baiji's prey by over-fishing, and noise and congestion caused by vessel traffic in the river have substantially degraded the Yangtze's environment. (Burnie & Wilson 2001, Reeves et al. 2003) 

The Three Gorges Dam on the Yangtze River will produce further stress on the baiji population. Although the Three Gorges Dam is upstream from the existing Gezhouba Dam, which already blocks the baiji from swimming further upstream, operation of the Three Gorges Dam will cause alteration of the Yangtze's hydrological regime, which will affect the baiji's habitat. The baiji generally occurs in large eddy counter-currents, such as are found below meanders, channel convergences and sandbars. Erosion from the water released below the dam is expected to eliminate these counter-currents for approximately 200 km (120 mi) downstream and degrade them for another 160 km (100 mi) downstream (IWC 2000). It is predicted by local experts that the baiji will become extinct in the near future whether the Three Gorges Dam is built or not (YVWRPB 1999).


Data on Biology and Ecology

Size and Weight:

The baiji weighs 135 - 230 kg (300 - 510 lb). Its length is up to 2.5 m (8.2') in females and 2.3 m (7.5') in males.

Habitat:

The baiji only occurs in freshwater rivers and lakes. It favors large eddy counter-currents such as are found below meanders; channel convergences; and areas in a river with structure, such as sandbars and areas adjacent to islands. In the Yangtze River, the baiji generally lives in the deeper sections, swimming to shallow water only to catch small fish.  In the past, it entered the large tributary lakes in summer when the water level was high and returned to the deep water of the Yangtze River to pass the winter. (Tan 1996, IWC 2000)

The baiji occurs in the Yangtze River & Lakes Global 200 Ecoregion. (Olson & Dinerstein 1998, Olson & Dinerstein 1999)

Age to Maturity:

More than 6 years in females; approximately 4 years in males (IWC 2000).

Gestation Period:

10 - 11 months.

Birth Season:

The baiji probably breeds and gives birth in the first half of the year. The peak calving season appears to be February to April. (Culik 2003)

Birth Rate:

The interbirth interval is 2 years. There is a single young at birth. (Nowak 1999)

Observed pregnancy rates are approximately 30% (IWC 2000).

Maximum Age:

Based on dentition, a wild individual was estimated to have lived 24 years (Nowak 1999).

Diet:

Any available species of freshwater fish is eaten.  The only selection criterion appears to be size: smaller than 6.5 cm (2.5") in width. Both surface- and bottom-feeders are taken as prey.

Behavior:

Feeding activity is primarily diurnal. At night the baiji often rests in areas of very slow current. Baijis surface without splashing and breathe smoothly. Short breathing intervals of 10 - 30 sec alternate with a longer one of up to 200 sec. 

Several underwater acoustic signals are emitted, including a whistle, which apparently function in communication. There also are series of clicks that probably are used for echolocation. (Nowak 1999)

It has been shown from photographic identification and sighting records that baiji groups make both local and long-range movements, although these movements are not believed to indicate periodic migration. The longest recorded distance traveled by an individually identifiable baiji was more than 200 km (120 mi) from the initial sighting location.  (Culik 2003)

Social Organization:

Baijis generally live in small groups of 3 - 4 animals, which may come together to make up a larger social unit of 9 - 16 dolphins. A group may congregate in the quiet area of an eddy for 5 - 6 hours. 

Density and Range:

In the late 1970's an average density of 0.25 individuals/km (0.4 individuals/mi) was observed in the Yangtze (Nowak & Paradiso 1983).


References

Bonner 1989, Burnie & Wilson 2001, Burton & Pearson 1987, Cetacea, Culik 2003, Ellis 1993, IUCN 1994, IUCN 1996, IUCN 2000, IUCN 2003a, IUCN 2004, IUCN 2006, IWC 2000, Klinowska 1991, Leatherwood & Genthe 1995, Macdonald 1984, Nowak 1999, Nowak & Paradiso 1983, Olson & Dinerstein 1998, Olson & Dinerstein 1999, Reeves et al. 2000, Reeves et al. 2003, Tan 1996, Terrambiente.org, WCMC/CMS, YVWRPB 1999


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