|Scientific Name:||Tenualosa thibaudeaui|
|Species Authority:||(Durand, 1940)|
|Red List Category & Criteria:||Vulnerable A2bcd ver 3.1|
|Reviewer(s):||Kottelat, M. & Juffe Bignoli, D.|
This species is endemic to the Mekong basin. The population is inferred to have declined by at least 30% over the last 10-15 years, and had undergone additional decline during 1970-1990. Causes of this decline are overfishing and dam construction. Assessed as Vulnerable based on population reduction caused by known threats that have not ceased, and the species is likely to be greatly impacted my mainstream dams on the Mekong if they were to be constructed.
|Range Description:||The species is endemic to the Mekong basin from northern Thailand to the Mekong Delta including the Tonle Sap Lake in Cambodia. Poulsen et al. (2004) considered it possible that the species distribution might extend into Myanmar and southern China.|
Native:Cambodia; Lao People's Democratic Republic; Thailand; Viet Nam
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||The species is seasonally and locally common at the beginning of the flooding season. Population decline is suspected to have reached 30% (C. Vidthayanon pers. comm. 2010) over the last 10-15 years, continuing a decline that had been observed in the 1990's by Baird and Roberts (1993). The species was previously abundant in the Khone Falls area but is now considerably rarer (Roberts 1993). Baird and Roberts (1995) reported that this species had declined the most of all the species that feature in the Khone Falls fishery since the 1970s; only four specimens were observed during the 15-day migratory period at the waterfalls in June-July 1993, and only a few individual fish were caught by fishermen in November-January 1993-94. Few were caught at the Khone Falls over the period 1993 to 1999 (Baran et al. 2005).|
|Habitat and Ecology:||
This species is found in rivers and large tributaries and it also moves to floodplain and lakes. It is strongly migratory, moving from the Tonle Sap Lake in Cambodia, and passes upstream through the Khone Falls in southern Lao PDR. The species grows to c.60 cm in length (Mattson et al. 2002). It is a filter-feeder.
There are at least two populations in the Mekong (Poulsen et al. 2004); one around Xayaboury in northern Lao PDR and upstream, the other in the lower Mekong from the Mekong Delta to Paksan in Lao PDR, downstream of Vientiane. The latter may represent more than one population, e.g., one above and one below the Khone Falls (Poulsen et al. 2004). The species is thought to spawn mid-stream, with juveniles feeding in flooded floodplain habitats and major tributaries. Deep pools in the Mekong mainstream highly vulnerable to impacts from dam operation, are considered important for the population between Stung Treng and Kratie in Cambodia.
|Use and Trade:||This species is heavily fished throughout its range. Roberts and Baird (2005) ranked the species amongst the highest socioeconomic value species in the Khone Falls fishery in Lao PDR. It is especially vulnerable to gill nets (Poulsen et al. 2004), and is a valued food fish throughout its range.|
|Major Threat(s):||The causes of population decline are overfishing for human consumption, and habitat degradation due to infrastructure development, especially dams which block species movements. The species is considered to be vulnerable to impacts from mainstream dam development on the Mekong (ICEM 2010). Baird (2009) noted that the proposed Don Sahong dam at the Khone Falls would impact migration of the (lower Mekong) population.|
|Conservation Actions:||Management of the species fishery is needed throughout the species range, along with research into the impacts of current and proposed dams on the species migration routes.|
|Citation:||Vidthayanon, C. 2013. Tenualosa thibaudeaui. The IUCN Red List of Threatened Species. Version 2015.2. <www.iucnredlist.org>. Downloaded on 28 July 2015.|
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