Baiji: Lipotidae

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BAIJI: Lipotidae

PHYSICAL CHARACTERISTICS

The baiji is a freshwater river dolphin that lives in the Yangtze (yang-see) River in eastern China. It has a long, narrow beak (snout), which curves slightly upward and grows longer with age. It has a steeply sloped forehead and tiny eyes that are set high on the sides of the head. These eyes are only slightly functional and leave the dolphin almost completely blind. This is why baijis use echolocation (eck-oh-loh-KAY-shun) to navigate and find food. Baijis have about 130 teeth, which are all alike in size and shape. The cone-shaped teeth are made for catching fish, not chewing.

The baiji has short, round flippers and a low, triangular shaped dorsal (back) fin. It has a very distinctive notch in the middle of its fluke, or tail. The body is a bluish gray, fading into white on its stomach. The average length for a baiji is between 6.5 and 8 feet (2 and 2.4 meters). Females grow to be larger than males. They weigh between 220 and 355 pounds (100 and 160 kilograms).

GEOGRAPHIC RANGE

The baiji lives along the 1,056 miles (1,700 kilometers) of the Yangtze River in eastern China. During the late spring and early summer, this freshwater dolphin moves to smaller streams and lakes if the water is high enough. At one time the lakes of Dongting and Poyang were home to the baiji year-round, but with the drop in water level these lakes can no longer support its presence.

HABITAT

The baiji is often found at places where tributaries (smaller streams) enter the river or along sandbars and dikes. When resting, it spends a lot of its time where the river is wide and slow moving. The baiji comes closer to shore to feed. During this time, it uses its long beak or snout to probe through the mud on the river's bottom.

DIET

Baijis, like many dolphins, are carnivores and have a diet consisting only of fish. A wide variety of species is consumed, limited only by the size of fish that can fit down its throat. Most of the fish are less than 2.6 inches (6.5 cm) long and weigh less than 9 ounces (250 grams). The baiji does not chew its food. It eats the whole fish at once, head first.

BEHAVIOR AND REPRODUCTION

Little is known about the baiji because so few of them are left in the world. In the wild they are extremely shy, easily frightened, and difficult to approach. The baiji are thought to live in groups of two to seven individuals, but groups as large as sixteen have been observed. They do not leap out of the water the way some other dolphins do, but only expose their head and beak when they come to surface after dives.

The baiji's dives are often short, only lasting ten to twenty seconds, but they can be as long as two minutes. While underwater, they emit a wide range of sounds. These includes a whistle sound used to communicate and a variation of clicks used in echolocation.

THE LEGEND OF THE BAIJI

There is a legend about the baiji that says there was once a young girl who was beaten by her stepfather. One day while they were out in a boat, the boat capsized and both the girl and her stepfather were thrown into the water. It is said that the girl emerged as a baiji while the stepfather emerged as a black finless porpoise.

Echolocation involves making sounds that bounce off objects. Sense organs pick up the echo or reflected sound and use that information to locate objects. The forehead of a dolphin is a lump of fatty tissue called the melon. The dolphin makes sounds (scientists disagree about how this is done) that seem to be focused through the melon and skull and then sent out into the environment. When the sounds bounce back, the echo is passed through special tissue in the lower jaw to the inner ear. From the time it takes to collect the echoes, their strength, and their direction, dolphins construct a "sound picture" of their environment. This process is so sensitive that they can "see" an object less than one-half inch (1.25 centimeters) across at a distance of 50 feet (15 meters).

The baiji is a very fast and strong swimmer and has been seen swimming over 60 miles (100 kilometers) in three days going against the current. While resting, the baiji stays in areas of very slow current.

Little is known about how this animal reproduces, because there have been no studies conducted on baiji reproduction. It is thought that males become mature at four years of age, while females mature at the age of six. A single calf is born in the spring, after a pregnancy of ten to eleven months. These calves are about 3 feet (91 centimeters) long and weigh between 6 and 11 pounds (2.5 and 4.8 kilograms). The baiji can live up to twenty-five years in the wild.

BAIJI AND PEOPLE

The baiji is very shy and has little interaction with humans. The presence of humans has made a major disturbance in the life of baijis. Chemical pollution, accidents, hunting, and habitat loss are all reasons for the decline in its numbers. Another large problem is the number of dams located along the Yangtze River. These dams alter the water level and flow of the current along the river and block fish migration. They also separate and isolate groups of baiji.

Propellers interfere with the dolphin's use of echolocation. Baijis often get confused and run into boats, hurting themselves. They can also be accidentally hooked or netted by fishermen. Many scientists believe that there are only a few dozen of these animals left in the world today. The baiji is the world's most endangered cetacean. There are no baijis held in captivity. Both a male and female who had been hurt and taken into captivity in different locations died.

CONSERVATION STATUS

Hope of saving the baijis is dim. Although it was declared a National Treasure of China and has been protected from hunting since 1975, the population continues to decline. Human use of the Yangtze River may be too intense for the baiji to survive.

There have been many ideas about how to help this dolphin survive, including capturing animals for breeding, developing "semi-natural reserves," and conducting population surveys. One idea even involved cloning the dolphin to help its population grow. In order to clone one of these dolphins at least three would need to be caught, which is a next to impossible task considering that fewer than ten are seen each year. Many successful breeding techniques have been developed for other dolphin species, including the bottlenosed dolphin. However, the baiji has not had the same luck as the bottlenosed, and every attempt to breed a baiji in captivity has failed. Now the idea of starting a breeding program seems even more unlikely because the only male who had ever been in captivity died in 2002 after living alone in a tank for twenty-three years. Sadly, despite what is being done to protect the baiji, it seems that they are doomed to extinction.

FOR MORE INFORMATION

Books:

Carwadine, Mark, and Martin Camm. Smithsonian Handbooks: Whales Dolphins and Porpoises. New York: DK Publishing, 2002.

Ellis, Richard. Dolphins and Porpoises. New York: Knopf, 1989.

Gowell, Elizabeth T. Whales and Dolphins: What They Have in Common. New York: Franklin Watts, 2000.

Mead, James G., and Joy P. Gold. Whales and Dolphins in Question: The Smithsonian Answer Book. Washington, DC: Smithsonian Institution Press, 2002.

Nowak, Ronald. M. Walker's Mammals of the World. Baltimore: Johns Hopkins University Press, 1995.

Smith, Alison M., and Brian D. Smith. "Review Status and Threats to River Dolphins and Recommendations for Their Conservation." In Environmental Reviews. Vol. 6, edited by T. C. Hutchinson. Ottawa, Canada: NRC Research Press, 1998.