The status and distribution of freshwater biodiversity in Indo-Burma

The United Nations World Charter for Nature (1982) states that “every form of life is unique, warranting respect regardless of it’s worth to man, and, to accord other organisms such recognition, man must be guided by a moral code of action.” It also states that “…man must acquire the knowledge to maintain and enhance his ability to use natural resources in a manner which ensures the preservation of the species and ecosystems for the benefit of present and future generations.” Most will recognize that, in the context of development planning, we now rarely respect nature, and we lack sufficient knowledge of biodiversity to inform decision making processes. This is certainly the case in the Indo-Burma region which is recognized as a global hotspot of biodiversity and has long been noted for the exceptionally high diversity of species within its inland waters.

Report "The Status and Distribution of Freshwater Biodiversity in Indo-Burma"

Our knowledge of species diversity within the inland waters of Indo-Burma is poorly documented and the region remains relatively under-surveyed. Large scale development of water resources is also underway throughout the region with noted current and potential impacts on freshwater species. There is therefore an immediate need to collate, and make freely available, existing knowledge on freshwater species distributions, ecological sensitivities, and habitat requirements for input to the decision making processes. Without such information, development is unlikely to proceed in a sustainable way and the impact on freshwater species will be severe.

In this volume we aim to address this knowledge gap and present the most up-to-date information on the distribution and extinction risk of freshwater species in all inland water ecosystems across the Indo-Burma hotspot, and where appropriate, the reasons behind their declining status. This represents the most comprehensive assessment yet of freshwater biodiversity at the species level for this part of the world. For managers, this information will assist in designing and delivering targeted action to mitigate and minimise impacts to these species. From a policy perspective, the information presented is fundamental to meeting national obligations under the Convention on Biological Diversity (CBD); the Ramsar Convention; and the Millennium Development Goals (MDGs). Information on species status is particularly important for Targets 11 and 12 of the CBD that state: “By 2020, at least 17 per cent of terrestrial and inland water areas, … especially areas of particular importance for biodiversity and ecosystem services, are conserved…” and “…by 2020 the extinction of known threatened species has been prevented and their conservation status, particularly of those most in decline, has been improved and sustained”, respectively.

Biodiversity within Indo-Burma’s inland waters is both highly diverse and of great importance to livelihoods and economies. This part of Asia is, however, embarking upon an unprecedented scale of development, in particular within its energy and water sectors. Such development is considered by many to be imperative if the region is to generate revenues and improve the livelihoods of this most densely populated region. Such development activities are, however, not always sustainable or compatible with species conser vation in inland waters which is seldom adequately considered within the development planning process.

As a major contribution towards the provision of information on the region’s freshwater species, IUCN’s Global Species Programme, in collaboration with its partners, conducted an assessment of the status (according to the IUCN Red List of Threatened SpeciesTM) and distribution of all described species of freshwater fishes, molluscs, odonates, crabs, and selected families of aquatic plants from across the Indo-Burma hotspot. A total of 2,515 species were assessed and documented. Existing additional information for 468 species of freshwater dependant amphibians, birds and mammals was also utilised to present a more comprehensive overview of the status and distribution of freshwater species across the region. With species information compi led for each of 1,082 ind ividua l river or la ke sub-catchments, this volume represents a major advance in knowledge for informing development actions at a scale appropriate for conservation management. The full dataset, including all species distribution files, will be made available through the IUCN Red List website (

Thirteen percent of all freshwater species assessed here are globally threatened. This level of threat is similar to that for other taxonomic groups in the region (12% of water birds, and 12% of amphibians are threatened) and is predicted to increase dramatically unless the ecological requirements of freshwater species are provided for in future development planning, in particular for development of the energy and water sectors. Major threats are identified as Pollution (from agriculture and forestry runoff in particular), Biological Resource Use (direct exploitation and/or habitat loss through deforestation), and Natural System Modification (dam construction and other modifications such as river clearance for navigation). The majority of threatened species are found along the mainstream Mekong River and the central and southerly parts of the Chao Phraya River. This distribution largely reflects the overall pattern of recorded species richness and the parts of the region where our knowledge is most complete – other centres of threat may also be detected as further information becomes available.

Major centres of overall species richness include the lowland areas within the lower and middle Chao Phraya River, the main stem of the Mekong River between the Lao PDR border and the confluence of the Mekong and Tonlé Sap rivers in Cambodia.

A number of river and lake basins are identified as a network of potential Key Biodiversity Areas (KBAs) most important for the protection of threatened and restricted range species. Those sub-catchments with the highest numbers of species meeting the KBA criteria are along the main stem of the Mekong river (in particular the region where Cambodia, Thailand and Lao PDR meet), the central Song Hong river system, the region surrounding Inlé Lake and the central Mae Khlong as it meets the Gulf of Thailand. The IUCN Red List is one of the most authoritative global standards supporting policy and action to conserve species. We hope this analysis, based in large part on an assessment of species Red List status, will provide new information and insights, which will motivate actions to help safeguard the diversity of life within Indo-Burma’s inland waters.

Key Messages:

  • The inland waters of the Indo-Burma hotspot are confirmed to be one of the world’s most species rich areas. For example, there is a higher diversity of species and genera of Odonata (dragonflies and damselflies) here than anywhere else in the Oriental Region, and the fish fauna is one of the richest in the world with more than 1,178 species known from the hotspot.
  • Current levels of threat for Indo-Burma freshwater species (around 13% of species are threatened) are close to those of similar freshwater assessments in Asia, such as in the Eastern Himalayas (7% threatened), and Western Ghats (16% threatened). However, many areas remain poorly surveyed (for example, the Red River) such that 37% of all species assessed were classified as Data Deficient, meaning their extinction risk could not yet be assessed. As more data become available, undoubtedly a number of these species will be reclassified as threatened, and the overall number of threatened species will increase accordingly.
  • Analysis of projected future threats suggests that, should current plans for construction of hydroelectric dams proceed as proposed, over the next decade the proportion of fish species threatened by dams will increase from 19% to 28%, and the proportion of mollusc species impacted by dams will increase from 24% to 39%.
  • In this context the planned large-scale development of hydropower schemes, both on the Lower Mekong main stem as well as on its major tributaries, is of major concern – especially as the lower main stem in Lao PDR and Thailand, as far as northern Cambodia was found to be one of the areas with highest species biodiversity, and highest numbers of threatened species.
  • Similarly, the Thai Government’s recent announcement of a package of almost US$12 billion of (mostly) large scale water infrastructure investments in the Chao Phraya Basin in response to the devastating floods of 2011, gives cause for concern – especially as the middle and lower parts of the Chao Phraya are two of the most biodiverse areas, with one of the highest concentrations of threatened species.
  • Pollution (largely from agricultural and residential run-off ) is identified as a major threat affecting many species, that must be addressed through setting of improved standards and regulations together with monitoring and enforcement, application of the polluter pays principle, and through Payment for Ecosystem Services (PES) approaches.
  • Over-harvesting is also a threat for some species and in certain locations. The recent suspension of 38 commercial fishing lot concessions in the Ton lé Sap (as well as concessions in other parts of Cambodia) for at least three years while stocks are assessed and more appropriate management can be developed, is a sign that governments are starting to recognise this issue and are willing to try to address it. To ensure that commercial concessions are not replaced by potentially even more damaging free-for-all “open-access” fisheries leading to a “tragedy of the commons”, more effort must be applied to supporting the development of community-managed fisheries with agreed use rules and restrictions.
  • Environmental Impact Assessments, Strategic Environmental Assessments, and Cumulative Impact Assessments should not be viewed as mere procedure and their recommendations must be taken into account. There must be follow-up after assessments are completed and the legal requirements of conducting them must be fulfilled. Such assessments should expressly require reference to the species data now made available through the IUCN Red List of T hreatened Species . I n the ca se of Mekong mainstream hydropower development, assessments must explicitly take into account trans-boundary impacts and, in the case of Thailand’s Flood Management Master Plan, impact assessments should not be omitted or overlooked for the sake of political expediency in urgently preventing a recurrence of the 2011 floods.
  • The overwhelming majority of protected areas in Indo-Burma have been designed and developed based on conservation needs (and opportunities) of terrestrial habitats and species. That freshwater habitats and species are protected at all is largely a result of their incidental inclusion within a forest protected area – and not as a result of a conservation plan specifically tailored to the protection of freshwater species. The protected areas systems of each country should be reviewed through the lens of freshwater species conservation priorities, gaps in the systems should be identified, and priorities established for extension of existing protected areas or designation of new areas to improve freshwater species conservation.
  • Thailand has the most Ramsar sites of any country in the region, but almost all of these are additional designations applied to already existing National Parks or non-hunting areas, and are not currently adding additional value to the conservation of freshwater species. In 2010–11 IUCN assisted the Government of Lao PDR to designate its first two freshwater Ramsar sites in Xe Champone and Beung Kiat Ngong, and assisted the Government of Viet Nam in designating Tram Chim (the most important area remaining in the Plain of Reeds in the Mekong Delta) as a Ramsar site. The process of identifying Key Biodiversity Areas started in this assessment should be built upon to help identify additional Ramsar sites (and other forms of conservation areas) within Indo-Burma.
  • Monitoring of environmental conditions in inland waters must include focus on species diversity and not only on recording changes in species biomass and productivity (as is the case for most fisheries). The currency for measuring fish biodiversity is the number of species, not kilograms, dollars or catch per unit of effort. Without employing a species based approach many species will be lost, leaving in place species-poor and potentially unsustainable fisheries.
  • Studies of direct interest to the local people should be translated into local languages and distributed freely. The results of too many studies are never made available and are therefore never used to benefit conservation.
  • Finally, we must not forget the UN World Charter for Nature’s statement that we respect all life regardless of its apparent worth to man. In other words we must still endeavour to protect those species that provide no obvious contribution to ecosystem services – including those smaller species of no apparent commercial value.

For full report, please download HERE


Work area: 
Viet Nam
North America
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