Wet season flood pulses in the Basin drive major fish
recruitment, inundating a large floodplain that backs up into the
Tonle Sap Lake in Cambodia. Dams would attenuate these flood
pulses and reduce fish recruitment. The Mekong Basin is
particularly rich in biodiversity, with 850 freshwater fish species,
or as many as 1100 if coastal or marine visitors are included. At
least 35% of the fish yield in the Mekong is comprised of species
that require migrations of up to a thousand kilometres or more for
reproduction (Barlow et al., 2008; ICEM, 2010a,b). Recruitment of
these fish species would be ‘‘fundamentally’’ undermined as dams
form barriers to migration (ICEM, 2010b).