The mammals (Lipotes vexillifer) is probably the rarest cetacean in existence; human activity severely threatens this dolphin (4). It is a very shy and graceful freshwater dolphin, with a rather stocky body, roughly the size of an adult human (3). It is bluish-grey in colour becoming whitish on the underside, but seems white or greyish from a distance (3). In common with other river dolphins, it has a very long, narrow beak with a slightly upturned tip, and small eyes placed high up on the face (2). The dorsal fin is positioned low on the body and is triangular in shape, and the flippers are rounded (2)(5). Females tend to be larger than males (2). The baiji is the only species in this genus, the name of which, Lipotes, derives from the Greek for ‘left behind’, referring to its limited range (3).
Also known as
Chinese river dolphin, white flag dolphin, whitefin dolphin, Yangtze River dolphin.
Baijis have long been recognised as one of the world’s rarest mammals, and are extremely shy animals, making observation of them in the wild extremely difficult. Consequently, relatively little is known of the species (6). They are most active through the night from early evening to early morning (3). They tend to live in small groups of three to four individuals, with the largest group ever seen comprising of 16 (2). A recent study found that they often swim with finless porpoises (Neophocaena phocaenoides), the only other cetacean in the Yangtze River, which is also threatened (classified as Vulnerable on the IUCN Red List) (1)(6). Baijis break the surface of the water without creating a splash and breathe smoothly (2). They feed on a wide range of freshwater fish (2), which are eaten whole (7).
It is thought that breeding occurs in the first part of the year, with most births peaking between February and April (2).
In the past, this river dolphin’s range extended from the mouth of the Yangtze River, China, upstream to 50 kilometres above the Gezhouba Dam (1). More recently, the mammals was found only in the middle and lower reaches of the Yangtze River (6), between two large tributary lakes, Dongting and Poyang (1). In 1997, just 17 individuals of this extremely rare species were seen; in 1999 this number fell to just four (6). During an expedition in November and December 2006 an intensive search was undertaken in the Yangtze River, but scientist failed to find a single baiji. It is now thought that the baiji may be extinct(4).
The baiji is an exclusive freshwater species (2). Within the Yangtze River, they are attracted to areas where tributaries meet the river, particularly where there are sand bars with large eddies (3)(6).
The Yangtze River is one of the world’s busiest waterways (3), and is subject to a great range of human pressures that have had a devastating effect on the mammals. The main threat causing the decline of this species in recent years is illegal fishing using electricity, which has accounted for 40 percent of known deaths. The dolphins have also become caught in fishing gear, and engineering explosions used to keep navigation channels open are another source of mortality. Vessels carrying pesticides occasionally overturn, causing poisoning of the ecosystem, resulting in further deaths (6). An additional source of pollution comes from the 15.6 billion cubic meters of wastewater discharged into the Yangtze every year, 80 percent of which is not treated. A huge volume of boat traffic uses the river; noise levels are high and boat strikes a possibility. Furthermore, the banks of the Yangtze have been greatly modified in order to prevent flooding of adjacent land; such projects have great impacts on the ecosystem, both during construction and from the resulting habitat changes. Dam construction has been shown to reduce the availability of fish, which is exacerbated by over-fishing and pollution. The recent construction of the infamous Three Gorges Dam, the largest dam in the world, is likely to affect fish stocks and natural flooding patterns (2). For many years the baiji population is thought to have been very small, which in itself may have caused serious problems; small populations often suffer low genetic fitness and are often less able to adapt to environmental changes (2).
In Chinese folklore, the mammals is dubbed ‘Goddess of the Yangtze’, a beneficent animal once revered by the fishing people of the river. The species was declared a National Treasure of China and has been a protected species since 1975 (3). However, this had very little effect on the population, which continued to decline despite conservation efforts and legal protection. It was thought that the only chance to save the species from extinction would be to remove all of the surviving individuals from the Yangtze into the ‘Baiji Semi-natural Reserve’ which was created in 1992 (6). However, since the unsuccessful search for any surviving baijis in 2006, it is unlikely that a captive breeding programme will now ever be possible (4). The World Conservation Union (IUCN) has now classified the baiji as Critically Endangered (Possibly Extinct); it cannot be definitively classified as Extinct until further surveys are undertaken (1). Sadly, it seems that this goddess of the Yangtze will be the first cetacean species to become extinct in modern times as a result of human activities (5).
The unpaired fin found on the back of the body of fish, or the raised structure on the back of most cetaceans.
A category used in taxonomy, which is below ‘family’ and above ‘species’. A genus tends to contain species that have characteristics in common. The genus forms the first part of a ‘binomial’ Latin species name; the second part is the specific name.
Zhang, X., Wang, D., Liu, R., Wei, Z., Hua, Y., Wang, Y., Chen, Z. and Wang, L. (2003) The Yangtze River dolphin or baiji (Lipotes vexillifer): population status and conservation issues in the Yangtze River, China. Aquatic conservation: marine and freshwater ecosystems, 13: 51 - 64.
Grzimek, B. (2004) Grzimek’s Animal Life Encyclopedia – Second Edition. Gale, Detroit.
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