habitat , one at sanbur and one at stuntrek, and another one just upstream at dontahongins in southern laos. and i think any of those dams could have a very significant impact on this population and potentially wipe it out even. >> river traffic is heavy close to cambodia's capital city, phnom penh. the mekong is the lifeblood of the country. people here get 80% of their protein from fish. that's why cambodians are so concerned about the effect the dam will have on the mekong ecosystem. chum hang tong is the head of a state-owned fishing operation in phnom penh. he's been campaigning for construction to be pushed back by ten years to monitor the effects on fish. but that appeal was rejected. the fish will no longer be able to migrate as needed. then we won't have enough fish. >> my tho is located in the mekong delta region in vietnam, 2,000 kilometers downstream from the dam planned in laos. but people here are worried, too. le than bac is a scientist studying fish stocks. he complains that laos isn't co-operating with the countries further downstream. >> we have a need for study but so far