<Nature and Our Future: The Mekong Basin and Japan>

1-3. Fish Diversity in the Mekong Basin
Fish and other freshwater aquatic species are the main source of protein for people who live in rural
areas of the Lower Mekong Basin (the four countries of the Lower Basin, not including China andBurma). With the exception of Vietnam’s Mekong delta, which is adjacent to the sea, the consumption
rate of freshwater fish is extremely high in almost all areas of the basin. This paper is an overviewof the use of Mekong River fish by people of the region from The Fisheries Baseline Assessment
Working Paper of the Mekong River Commission’s Strategic Environmental Assessment (ICEM2010).

The Diversity of Fish Species in the Mekong Basin
The Fisheries Baseline Assessment Working Paper estimates the diversity of fish species in theMekong River from data registered in the FishBase database of fish inhabiting 204 rivers and 32 lakes
worldwide. According to data registered as of 2009, it has been confirmed that the 781 fish species
found in the Mekong River is second only to the 1,271 species of the Amazon River, showing thatthe Mekong River is the second river in the world for fish diversity. According to a report by theWorld Wildlife Fund (WWF), the Mekong River basin is a biodiversity hotspot where more than 279
new species of fish have been discovered in the last decade. It was previously estimated that there
were around 1,200 species of fish in the Mekong River, but at present it is thought that there are 850
freshwater species, and that around 1,100 species inhabit the river if marine fish that make temporary
incursions into the Mekong River delta are also included. Furthermore, 197 fish species are registeredin the FishBase for the Cambodian lake Thonle Sap, indicating that this lake is fourth in the world forfish species diversity (Japan’s Lake Biwa is sixth, with 69 species).
The number of fish species in 20 locations in the river basin (including tributary river sub-basins) isshown in the following table:
Location
China-headwater
China-upper reachSpecies
2434

Families
34

Endemic
44

China-middle reach
China-lower reach

48
122

821

715

Northern Laos
Nam Ou

140
72

30
1526
29

Nam NgumNam Mang
Nam Kadinh

156
57
99

27192143
1738

Songkhram
Xe Bang Fai

216
157

40
31

3951

Xe Bang HiangMun/Chi

160
270

33
38

47
49

Downstream of the Khone Falls
Stung Treng-Kratie

168
204

34
37

25
33

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<Nature and Our Future: The Mekong Basin and Japan>

Sekong
Sesan

214
133

33
26

63
24

SrepokThonle Sap

204
284

32
45

38
31

Mekong Delta

486

73

28

Table: Species richness in 20 locations of the Mekong Basin (ICEM 2010:11)

It can be seen from the table that even excluding the Mekong River delta, where marine fish also
contribute to the diversity of fish species, the Mekong River and its tributaries are very rich in aquaticlife. There are especially abundant numbers of fish species in Thailand’s Songkhram River basin
and Mun/Chi basin, as well as in the Mekong mainstream between Stung Treng and Kratie, andCambodia’s Sekong and Srepok basins.
References
International Center for Environmental Management (ICEM). 2010.
Mekong River Commission (MRC) Strategic Environmental Assessment (SEA) for Hydropower on the Mekong Mainstream:Fisheries Baseline Assessment Working Paper. Vientiane, Lao PDR: MRC.
http://www.mrcmekong.org/about-the-mrc/programmes/initiative-on-sustainable-hydropower/strategic-environmental-assessment-ofmainstream-dams/

Yuka Kiguchi<1-3>2