Baiji - Lipotes vexillifer

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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.

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.

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.

Baiji inhabit rivers. 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 breathe with little surface disturbance. Baiji movements include both short- and long-distance (200+ km) meanderings.

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 females reach sexual maturity at ages of about 4 and 6 years, respectively.

Baiji are opportunistic feeders; prey species include a large variety of freshwater fish species, the only limitation probably being size.

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 (IUCN) cetacean in the world and is endangered (ESA). 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.

• iOBIS
• World Register of Marine Species (WoRMS)
• Encyclopedia of Life
• Catalog of Life
• Integrated Taxonomic Information System (ITIS)
• Barcode of Life

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., D. Wang., R. Liu, Y. Hua, Y. Wang, Z. Chen and L. Wang. 2001. Latest population of the baiji (Lipotes vexillifer) and its conservation in the Yangtze River, China. pp. 41-53 in [Proceedings of] Conference on Conservation of Cetaceans in China, March 2001, Shanghai. Published by Ministry of Agriculture, P.R. China.

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, San Diego, CA.