|Scientific Name:||Lipotes vexillifer|
|Species Authority:||Miller, 1918|
|Taxonomic Notes:||This species was listed in the 1996-2002 IUCN Red Lists under the family Platanistidae.|
|Red List Category & Criteria:||Critically Endangered C2a(ii); D ver 3.1|
|Assessor(s):||Smith, B.D., Zhou, K., Wang, D., Reeves, R.R., Barlow, J., Taylor, B.L. & Pitman, R.|
|Reviewer(s):||Perrin, W.F. (Cetacean Red List Authority) & Stuart, S.N. (Global Mammal Assessment Team)|
The Baiji is probably the most threatened cetacean in the world. It is a relict species and the only living representative of the family Lipotidae (Zhou, Qian and Li 1978). It meets the definition of a Critically Endangered (CR) species, as it is facing an extremely high risk of extinction in the wild.
Criterion A. Although the species may qualify as CR under this criterion, the lack of standardized survey data makes it difficult to substantiate and quantify the declining trend in population size. Therefore, it was judged more appropriate (i.e., less complicated) to use other criteria for the CR classification.
Criterion B. The species' extent of occurrence has declined by at least several hundred linear kilometers in the Yangtze (from approximately 1,700 to no more than 1,400 km; Zhang et al. 2003) and it reportedly no longer occurs in the two large appended lakes (Dongting and Poyang). However, neither its extent of occurrence nor its area of occupancy appears to fall below the threshold level for CR.
Criterion C. The total population (all ages) is certainly less than 250 and therefore less than 250 mature individuals exist. Subcriterion C2 is probably more suitable than subcriterion C1, in that a continuing decline in numbers of mature individuals is projected and all individuals are considered to belong to a single subpopulation (i.e., 90% of mature individuals are in one subpopulation: C2a(ii)). The species therefore qualifies as CR under this criterion.
Criterion D. There is no evidence to suggest that the total population size is as large as 100 and it is probably no more than a few tens of individuals. A precautionary interpretation of the evidence is that there are fewer than 50 mature individuals, and therefore the species qualifies as CR under this criterion.
Criterion E. The viability of the species was assessed at a workshop in Nanjing, China, in 1993 (Ellis et al. 1993, Zhou et al. 1994). However, results were equivocal as rigorous estimates of key parameters (e.g., population size, natural and human-caused mortality rates, intrinsic rate of increase) were not available and therefore the range of possible outcomes was great.
In addition to the above considerations, which justify CR, this species may already be extinct (Possibly Extinct (PE)). The last documented sighting (supported by photographic evidence) was in 2002 and the last confirmed stranding was in 2001 (Turvey et al. in prep.). In November and December 2006 a comprehensive visual and acoustic survey failed to find a single Baiji in the Yangtze River (Turvey et al. in prep.). Two research vessels covered the known habitat of baiji from Yichang to Shanghai in both the upstream and downstream directions (for quadruple coverage). In addition, one vessel towed a hydrophone to listen for Baiji whistles and clicks during the downstream survey. Although Dongting and Poyang lakes were not covered in the 2006 Yangtze mainstem survey, no Baiji have been seen since 2000 by researchers studying Finless Porpoises in those lakes. A few undocumented sightings have been reported since 2004, but there are no photographs or physical evidence for the species' continued existence. The preponderance of evidence indicates that the Baiji is very close to extinction or may already be extinct.
|Range Description:||In recent times, this species has been endemic to the Yangtze River of China. Some individuals were seen in the Fuchun River, immediately south of the Yangtze, during the great flood of 1955 but disappeared from that area after construction of a hydropower station in 1957 (Zhou 2002). Baiji also occurred historically in Dongting and Poyang Lakes, both appended water bodies of the Yangtze (Zhou et al. 1977, Chen et al. 1980), but apparently do so no longer (Yang et al. 2000, Zhang et al. 2003). Their upstream limit in the Yangtze changed from the Three Gorges area approximately 35 km above Gezhouba Dam near Yichang in the 1940s to approximately 170 km below the dam site near Jingzhou (formerly called Shashi) in the 1990s (Zhou 2002, Zhang et al. 2003). These dolphins were once observed as far downstream as the river mouth near Shanghai (Zhou and Li 1989). No dolphins were found downstream of Jiangyin, located 256 km upstream of the mouth, during surveys in 1997-99 (Zhang et al. 2003). (See Figure 1 in the attached PDF showing the Yangtze River and the locations used to describe the distribution of the baiji).|
|Range Map:||Click here to open the map viewer and explore range.|
The first estimate of abundance based on quantitative survey data (1979-81) was made by Zhou (1982), who guessed that there were only about 400 animals all told. On the basis of surveys conducted in 1985-86, Chen and Hua (1989) made an educated guess that the total population was around 300. Surveys by Zhou and Li (1989) between 1982 and 1986 suggested that there were 100 baiji in a 770 km segment of the lower Yangtze from Hukou to the river mouth, compared with 78 to 79 dolphins counted by Chen and Hua (1989) in the same segment in 1985-86. Repeated surveys of a 500 km segment of the lower Yangtze (Nanjing-Hukou) in 1989-91 produced a maximal count of 12 individuals, leading Zhou et al. (1998) to infer a total abundance of about 30 baiji in that river segment. Those authors reasoned that if the species still inhabited its historical range of about 1,700 linear kilometers of river, with a density similar to that found in their study area, the total population in the early 1990s would have been only about 100. Attempted comprehensive surveys of the entire species' range in 1997-99 resulted in a maximal count (November 1997) of 13 dolphins (including one calf), leading to the generally accepted view that abundance had continued to decline and that the total population was by that time very small. The sighting rate in the three years of surveys declined at an annual rate of about 10% (Zhang et al. 2003). Informed guesses in the early 2000s were that there could be only "a few dozen" (Zhou 2002) and "very likely ... less than a hundred" (Reeves et al. 2003) baiji left (also see Wang 2000, IWC 2001, Zhang et al. 2003). Although no credible time series of counts or abundance estimates is available to provide a rigorous evaluation of trends, there is an overwhelming consensus that the baiji population declined rapidly over the past several decades.
During surveys in the late 1990s baiji were 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 (Wang 2000, Zhang et al. 2003).
More recent evidence suggests that this species might already be extinct. The last documented sighting (supported by photographic evidence) was in 2002 and the last confirmed stranding was in 2001 (Turvey et al. in prep.). In November and December 2006 a comprehensive visual and acoustic survey failed to find a single baiji in the Yangtze River (Turvey et al. in prep.). Two research vessels covered the known habitat of baiji from Yichang to Shanghai in both the upstream and downstream directions (for quadruple coverage). In addition, one vessel towed a hydrophone to listen for baiji whistles and clicks during the downstream survey. Although Dongting and Poyang Lakes were not covered in the 2006 Yangtze mainstem survey, no baiji have been seen since 2000 by researchers studying finless porpoises in those lakes. A few undocumented sightings have been reported since 2004, but there are no photographs or physical evidence for the species' continued existence. The preponderance of evidence indicates that the baiji is very close to extinction or might already be extinct.
|Habitat and Ecology:||Generally found in eddy counter-currents below meanders and channel convergences (Hua et al. 1989, Zhou and Li 1989, Zhang et al. 2003). Baiji prey on fish of many sizes and various species, including both surface and bottom feeders (Chen et al. 1997).|
The range contraction and the decline in baiji abundance were caused by a combination of factors, including: possibly some level of direct exploitation historically; incidental mortality from interactions with fisheries; vessel traffic, management of navigation channels, and harbor construction; and loss or degradation of habitat by water development, land use practices, and pollution.
During China's "great leap forward" the baiji's traditionally venerated status as "goddess of the river" was denounced and baiji skin was used to produce handbags and gloves (Zhou and Zhang 1991).
Entanglement in fishing gear was estimated in the 1970s to 1980s to have been responsible for at least half of observed mortality (Lin et al. 1985, Zhou and Li 1989, Chen 1989, Chen et al. 1997). Longlines with thousands of unbaited hooks used for snagging bottom fish ("rolling hooks") accounted for 7 of 13 entanglement deaths recorded in the lower Yangtze between 1978 and 1985 (Zhou and Li 1989) and 15 of 28 in the middle reaches between 1973 and 1983 (Zhou and Wang 1994, also see Chen et al. 1997). Additional deaths from entanglement in rolling hooks were documented in the 1990s (Zhou et al. 1998). Baiji often have scars and open wounds from rolling hooks, and hook remains are sometimes found in the stomachs of dead animals (Lin et al. 1985, Zhou and Li 1989). Deaths also result from entanglement in gill and fyke nets (Zhou and Wang 1994). According to Zhou et al. (1998), both rolling hooks and fyke nets are banned in the Yangtze "because both are harmful to fisheries resources, and because of incidental killing of Baiji", but enforcement of these prohibitions is "very difficult" and therefore incidental mortality is likely to continue.
Electric fishing, although "strictly banned" in the Yangtze (Zhou et al. 1998), is widely practiced, particularly in the centre of the baiji's distribution (IWC 2001). By the early 2000s this fishing method had come to be viewed as the most important and immediate direct threat to the baiji's survival (Zhang et al. 2003). The electric shocks kill baiji outright (Chen and Hua 1989, Wang Ding in IWC 2001: 276) and unselectively kill other aquatic organisms, including the baiji's prey.
Propeller strikes have killed and injured baiji (Zhou and Zhang 1991, Chen et al. 1997) and are considered an increasing threat in view of the rapid industrial and economic growth of China, with its associated expansion of traffic on the Yangtze (Chen 1989, Chen and Hua 1989, Zhou and Li 1989, Zhou 1992, Zhou et al. 1998).
Explosives, used to deepen or widen river channels or for fishing, are another cause of baiji mortality (Lin et al. 1985, Zhou and Li 1989, IWC 2001).
Water development has transformed the baiji's habitat in important ways, e.g., by interrupting their movements upstream of dams, eliminating their access to tributaries and appended lakes, and reducing fish productivity (Liu et al. 2000). A dead baiji found at the bottom of a gate for a ship lock in a Yangtze tributary may have been killed accidentally by the structure (Liu et al. 2000). Chen and Hua (1987) predicted that the controversial Three Gorges Dam, completed in the early 2000s, would eliminate counter-current habitat for approximately 200 km downstream and degrade the existing counter-current systems for another 160 km downstream. Further, stratification in the reservoir will cause the water released below the dam to be cooler than previously, potentially affecting baiji and their prey. The downstream effects of Gezhouba Dam were not as extreme as those predicted for Three Gorges Dam because the former is a low-head, run-of-the-river structure (Zhong and Power 1996), meaning that sediment is allowed to pass through (which allows the formation of the counter-currents where baiji are generally found - see above) and no reservoir forms. Another effect of Three Gorges Dam will be to facilitate large ship traffic in the upper reaches of the Yangtze and thereby increase the amount of underwater noise and the incidence of vessel collisions with baiji (Chen and Hua 1989).
Industrial expansion and intensified agriculture (both facilitated by water development) have already caused major ecological problems in the Yangtze system. For example, Dongting and Poyang Lakes have become much shallower because of siltation from deforestation and agricultural development; in fact, it has been suggested that Dongting Lake could disappear altogether within a decade (Liu et al. 2000).
Pollutant loads in the Yangtze are expected to increase with industrialization and the spread of modern agricultural practices. Approximately 40% of China's industrial and agricultural output comes from the Yangtze basin, with more than 16 billion cubic meters of wastewater discharged into the river annually, of which more than 12 billion cubic meters is industrially polluted and largely untreated (Zhou et al. 1998).
The baiji is designated in the First Category of National Key Protected Wildlife Species and has full legal protection throughout its range. Protection from deliberate killing or injury appears to be effective but, as noted above, prohibitions on harmful fishing methods are generally not very effective and there is no evidence that baiji are protected in any way from the mortality, injury, and health impairment caused by the other threats listed above.
Since the late 1980s, the primary strategy to prevent the baiji's extinction was to capture as many dolphins as possible and to introduce them into "semi-natural reserves", one of which (Tongling) was approved by the Chinese government in the 1980s, and the other (Shishou) in the 1990s. The approach of using semi-natural reserves as components of a broad-based conservation strategy was endorsed by international panels of scientists in 1986 (Perrin and Brownell 1989) and 1993 (Ellis et al. 1993, Zhou et al. 1994). It was premised on the assumption that the total dolphin population in the 1980s was approximately 300 and declining. Importantly, it was also premised on the expectation that an ex situ breeding population, preferably housed at two or more sites, would provide surplus animals for replenishment or reestablishment of the wild population, and not be viewed as an end in itself (Perrin and Brownell 1989, Ralls 1989, Perrin 1999).
However, the expectation that sufficient numbers of baiji could be caught and placed in the reserves to establish a viable ex situ population has proven unrealistic. Six capture expeditions, each lasting 2 to 3 months, were conducted between Chenglingji and Gongan in the 1990s. In 1995 a female baiji was caught and released in the Shishou reserve, a 21 km oxbow channel of the Yangtze River (Liu et al. 1998). Less than seven months later her carcass was found entangled in the escape-prevention net at the outlet of the reserve. At that time, one other baiji was in captivity - a male (Qi Qi) that had been rescued from fishing gear and rehabilitated in 1980. This animal remained in its dolphinarium tank at the Institute of Hydrobiology of the Chinese Academy of Sciences in Wuhan until it died in 2002. At the time of this writing (August 2004; update in April 2007), no Baiji were in either of the semi-natural reserves or in the dolphinarium at Wuhan.
Scientific opinion has been divided on how to proceed with baiji conservation efforts. The Scientific Committee of the International Whaling Commission reviewed the status of the baiji in 2000, but members were unable to reach consensus on whether further attempts at live-capture should or should not be made (IWC 2001). The IUCN SSC Cetacean Specialist Group recommended in 2003 that: (1) available resources should be devoted to eliminating the known threats to the species in its natural habitat; (2) immediate action should be taken at national, provincial and local levels to fully enforce the bans on rolling hooks and electric fishing; and (3) if the capture/translocation effort continues, capture operations should be improved to prevent dolphin injury or mortality, water quality in the reserve should be kept at a high standard and finless porpoises should be removed to ensure against deleterious interactions between them and the dolphin(s) (Reeves et al. 2003). The Chinese Ministry of Agriculture has developed a baiji conservation plan emphasizing the ex situ approach (Ministry of Agriculture 2001, Wang and Zhang 2002).
With the intention of improving the status of fishery resources, the central Chinese government has, since 2001, banned fishing in the entire middle and lower reaches of the Yangtze River (including appended lakes and tributaries) between 1 April and 30 June. This measure, if effective, could give some seasonal relief to baiji from one of the more serious lethal threats to their survival. In addition, serious efforts have been made in recent years to protect baiji and improve their habitat in the Xin-Luo National Baiji Reserve (established in 1992) and in two smaller reserves run by provincial governments (Zhenjiang and Tongling sections). In the Xin-Luo Reserve patrol boats monitor fishing activity, collect baiji sightings, rescue injured animals, and investigate dolphin deaths. Several shore-based monitoring sites have been established in the reserve to observe baiji. Perhaps the most important work carried out by reserve staff is that of enforcing the ban on electric fishing.
It is listed on CITES Appendix I.
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|Citation:||Smith, B.D., Zhou, K., Wang, D., Reeves, R.R., Barlow, J., Taylor, B.L. & Pitman, R. 2008. Lipotes vexillifer. The IUCN Red List of Threatened Species. Version 2015.2. <www.iucnredlist.org>. Downloaded on 03 September 2015.|