Mekong River fishermen have already suffered dramatically from dams and irrigation works, which have decimated fish stocks and undermined livelihoods that supported families for generations.
Nguyen Anh Duy, a 33-year-old, third-generation fisherman from the Mekong Delta in Vietnam, is one of the millions of rural people who rely on the fertility of the river to make a living. However, his occupation as a fisherman who depends on wild-caught fish from the river will be lost in a few years.
"I am a fisherman who has caught fish in the water around here for all my life. My father and my grandfather also did the same job as me. I was born and grew up here," he said about his life.
He and his wife and two children live together within the small confines of his boat.
"The fish have been gradually disappearing over the years. My catch is getting smaller and smaller. In the dry season, most fish are small and hard to catch. But the fish price has gone up every year too," he said.
Despite the higher price, his earnings do not seem to be enough for his family, as he has had to let his parents raise his children.
If the fish still continue to decrease, he may have to change to working in the city.
Thongbi Pongthin, a fisherman in Ubon Ratchathani, tells a sadly similar story.
"The fish are harder to catch because the water level is becoming more unstable. Sometimes it's a high tide very quickly and then comes a very low tide. This drives many fish away. There is also the use of electricity to shock the fish by some Lao fishermen, which kills many fish," he said.
Dams on the upper reach of the river have made the flow downstream very uneven. When Thongbi was young, fish were much more abundant than now.
"Many fishermen in the province changed jobs to be a worker in Bangkok, as there were fewer fish to catch. I also can't depend solely on catching fish anymore. Fortunately, my family has a vegetable garden, so our family has another source of income, but I think I'll have to quit fishing soon," he said.
Nguyen Huu Thien, a Vietnamese freelance researcher on wetland ecology and conservation of natural resources, said the building of dams on the Mekong is the major reason for depleting stocks.
"There are two types of fish in the Mekong. The first are those that live in a specific area and do not need to migrate and the second are migrating fish that need to travel up the river to their spawning site. The dams on the river are barriers that block the migration of the fish, so many species of fish cannot go to their breeding site," he said.
The dams had led to a dramatic decline in fish stock, he said, with over 220,000 tonnes of fish lost each year because the fish cannot reproduce like they did in years gone by.
Fish in the Mekong could not pass any barrier taller than 30 metres, he said. The fish ladders that dam builders claim allow fish to pass do not actually work for species in the Mekong.
"Fish ladders were designed for big fish like salmon and they are untested on the Mekong. The fish here cannot climb the high ladder," he said.
Not only is passage blocked, nutrient-rich sediment is also trapped by the dams. Nutrients carried by the current sustain not only the fish in the river but also marine fish in the Delta.
More dams on the Mekong would result in a devastating loss of fish, which would cast a major shadow on the food security of the region, he said.