What We Do

Background: current knowledge of the status of freshwater biodiversity

Past Red List assessments of freshwater taxa have rarely been conducted on a comprehensive basis so it is difficult to provide a reliable estimate for their global levels of threat. However, the FBU and its partners have now completed several comprehensive regional assessments and the initial results are very worrying. For example, 54% of Madagascar’s native freshwater fish species are threatened. In Eastern Africa 54% of freshwater crabs and 16% of the molluscs are threatened, as are 56% of freshwater fishes endemic to the Mediterranean basin. The SSC's Global Amphibian Assessment also reports high levels of threat with 32% of amphibians assessed as globally threatened and a further 23% as Data Deficient. The freshwater mussels are perhaps the best known of freshwater molluscs and their status is well known for North American populations of which 35% of the 297 taxa are listed as Extinct, Endangered, or are candidates for listing as Endangered.

Future work aims apply the comprehensive assessment approach that we have developed on a global scale. Other regions we plan to assess in the immediate future include the Western Ghats and Indo-Burma biodiversity hotspots, and high altitude watersheds in the Himalayas. We work closely with the IUCN Centre for Mediterranean Cooperation in undertaking regional assessments of freshwater species within the Mediterranean basin which have revealed high levels of threat for some species.

The major threats to freshwater biodiversity include habitat loss, introduction of alien species, pollution, and over-harvesting. There are many examples to illustrate the severity of the situation: 

  • In the United States, 98% of an estimated 5.2 million kilometres of streams are sufficiently degraded to be unworthy of federal designation as wild or scenic rivers.
  • 200 of the 522 (38%) of European freshwater fish species are threatened with extinction and 12 are already extinct.
  • Industrial agriculture around the Aral Sea in the last 30 years has resulted in an approximate halving of the lake's surface area and depth, and a tripling of its salinity.
  • Only two of Japan's 30,000 rivers are neither dammed nor modified in some way.
  • In Lake Victoria, the introduction of a single alien species, the Nile Perch Lates niloticus has led to the possible extinction of an estimated 200 species of endemic fishes.
  • Nearly all inland fisheries, with the possible exception of North America and parts of Europe are considered to be overexploited.


  • To build expertise and capacity on freshwater biodiversity through the establishment of regional networks
  • To establish a freshwater biodiversity information system within the SSC Species Information Service (SIS)
  • To carry out status assessments (IUCN Red List) for key groups of freshwater species and identify critical sites for the conservation of these species groups
  • To determine key threatening processes and priority conservation actions in each region and assess the priority requirements for freshwater biodiversity conservation
  • Communicate the results of the project to governments, donors and NGOs to raise awareness and include freshwater biodiversity conservation in their priorities for action
  • Demonstrate the link between biodiversity and livelihoods through interdisciplinary approaches.



Sekong River, Lao PDR

Indo-Burma Freshwater Biodiversity Assessment

The Indo-Burma project, funded by the Critical Ecosystem Partnership Fund (CEPF), focused on assessing the conservation status of all described species of freshwater fishes, molluscs, odonates and selected families of aquatic plants native to the Indo-Burma hotspot. Assessment areas included the Salween, Chao Praya and the Mekong rivers, as well as coastal basins in Thailand and Viet Nam.

 Click here for further information.

Regional freshwater biodiversity assessments

The Freshwater Biodiversity Unit is conducting regional assessments of the status and distribution of a number of priority groups of freshwater taxa. The following assessments have been completed: