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Lipotes vexillifer (Chinese River Dolphin)

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species image
Image credit: Institute of Hydrobiology, Chinese Academy of Sciences

Taxonomy & Nomenclature
Scientific Name Lipotes vexillifer
Taxonomic Rank Species
Original Description Miller, 1918
Scientific Synonyms (since 1950)
None.
Common Name
Chinese River Dolphin
All Common Names Chinese: baiji
English: Yangtze River dolphin, Chinese river dolphin
Taxonomic Parents Kingdom: Animalia
  Phylum: Chordata
    Subphylum: Vertebrata
      Class: Mammalia
        Subclass: Theria
          Infraclass: Eutheria
            Order: Cetacea
              Suborder: Odontoceti
                Family: Iniidae
                  Genus: Lipotes
Taxonomic Children
Taxonomic # 180409
Taxonomic data is courtesy of the Integrated Taxonomic Information System (ITIS)

Physical Description / Field Identification
Outside of China, very little was known of the Chinese River Dolphin's biology until recently.  They have a fairly typical river dolphin appearance.  These animals are moderately robust, with long, slightly-upturned beaks, rounded melons, low triangular dorsal fins (set about 2/3 of the way back from the snout tip), and broad rounded flippers.  The eyes are small and set higher on the face, compared to those of oceanic dolphins.  Although their vision is apparently poor, the eyes are functional.  Male baiji reach sizes of 2.3 m and 135 kg, and females reach 2.5 m and over 167 kg.  Baiji, or Chinese river dolphins, are predominantly bluish gray above and white to ashy-white below.  There are light brushings on the side of the face and the side of the tail stock.  Each tooth row contains 31-36 conical teeth.

Can be Confused With
The only other small cetacean in the baiji's range is the finless porpoise, which can be readily distinguished by its much darker coloration and absence of a beak or dorsal fin.

Distribution

Range:  Yangtze River in China

The baiji is found only in the middle and lower reaches of the Yangtze River in China.  The normal range was formerly broader, including several large lakes the dolphins entered during the flood season.  Baiji may still enter some of these lakes during periods of intense flooding.

Links to Distribution Map at Sea Around Us Project

Map of OBIS-SEAMAP Data Points

Existing observations across multiple datasets within OBIS-SEAMAP are indicated with red points.
Species distributions (pink background polygon if present) were digitized by Kristin Kaschner as part of the Sea Around Us Project predominantly from Jefferson et al (1993).

Reference
Jefferson, T.A., S. Leatherwood, and M.A. Webber. 1993. FAO species identification guide. Marine mammals of the world. Rome, FAO. 1993.320. p. 587 figs.

Ecology and Behavior

Habitat:  River

Groups of two to six baiji are most commonly seen, but aggregations of up to 16 animals sometimes form.  These dolphins are generally shy of boats, and their surfacings are shallow, often exposing only the top of the head, dorsal fin, and a small part of the back.  They generally breath with little surface disturbance. Baiji movements include both short- and long-distance (200+ km) meanderings.

Reproduction:

The peak calving season appears to be February to April.  Apparently, newborn Chinese river dolphins are less than 92 cm in length.  Both males and feamles reach sexual maturity at ages of about 4 and 6 years, respectively.


Feeding and Prey

Feeding Mode:  Opportunistic feeders

Prey Species:  A large variety of freshwater fish species make up the diet of the baiji, the only limitation probably being size.


Threats and Status

Main threats include:

Mortality from fishing gear, such as rollings hooks (a type of snagging gear). dynamite and electricity fishing

Habitat destruction (as the areas around the Yangtze are dramatically modified to meet the needs of the surrounding human population)

Pollution

Vessel collisions

Prey depletion

Conservation status:

The baiji is widely acknowledged to be the most critically-endangered cetacean in the world.  The total current population, although not known precisely, is declining and probably does not number more than 50-100 individuals.  The threats are only becoming more serious, and it appears likely that the baiji will be the first species of cetacean to have been wiped-out by human activities. Critically Endangered (IUCN); Endangered (ESA).


References

CHEN, P., R. LIU, D. WANG, AND X. ZHANG. 1997. Baiji biology husbandry and conservation. Science Publishers/Chinese Academy of Sciences, 252 pp.

CHEN, P. 1989. Baiji Lipotes vexillifer Miller, 1918. Pp. 25-44 in S. H. Ridgway and R. Harrison, eds. Handbook of marine mammals, Vol. 4 River dolphins and the larger toothed whales. Academic Press.

LEATHERWOOD, S., AND R. R. REEVES. 1994. River dolphins a review of activities and plans of the Cetacean Specialist Group. Aquatic Mammals 20:137-154.

LIU, R., J. YANG, D. WANG, Q. ZHAO, Z. WEI, AND X. WANG. 1998. Analysis on the capture, behavior monitoring and death of the baiji (Lipotes vexillifer) in the Shishou Semi-nature Reserve at the Yangtze River, China. IBI Reports 8:11-22.

ZHANG, X., ET AL. 2001. Latest population of the baiji (Lipotes vexillifer) and its conservation in the Yangtze River, China. Pp. 41-53 in P. Ministry of Agriculture, eds. Conference on Conservation of Cetaceans in China. Government of PRC.

ZHOU, K., J. SUN, A. GAO, AND B. WÜRSIG . 1998. Baiji (Lipotes vexillifer) in the lower Yangtze River movements, numbers, threats and conservation needs. Aquatic Mammals 24:123-132.

ZHOU, K. 2002. Baiji Lipotes vexillifer. Pp. 58--61 in W. F. Perrin, B. Würsig and J. G. M. Thewissen, eds. Encyclopedia of marine mammals. Academic Press.

Relevant OBIS-SEAMAP Datasets (# sets: 0)

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