Vientiane: Mekong River levels in parts of Laos have hit their lowest in 50 years.
The situation has alarmed the millions who depend on what is the world`s largest inland fishery with an estimated annual catch of about 3.9 million tonnes, according to the Mekong River Commission (MRC).
Fisherman Phimmalang Sengphet paddles his boat to the sandy banks of the Mekong River in Laos and inspects his meagre haul. "We can`t even catch enough to feed ourselves," he says wearily.
The 38-year-old was able to net more than 10 kilos (22 pounds) of fish a day this time last year, but now he is lucky to bring home just half that. He blames the unusually low water levels – the most extreme he has ever seen.
"We want to know why. This is our life, catching fish to sell at the market. This is our business to provide for our families," he says as he wanders back to his village on the outskirts of the capital Vientiane.
"In Laos we don`t have the sea, we only have the Mekong for water and for food, so it`s very important to us," said another villager, 63-year-old Som Sirivath, as she waded waist-deep into the river in search of some supper.
The ebbing flows are not confined to land-locked Laos, one of Asia`s poorest nations.
In the upper Mekong basin in China`s southwest, more than 24 million people are short of drinking water as a result of the worst drought in a century. Downstream, the north of Thailand has also suffered five-decade river lows.
"Many people I know have changed to agricultural work because they can`t live on income from the fishing industry," said Niwat Roykaew, head of a local conservation group in the northern Thai province of Chiang Rai.
The cause of the dwindling waterway is a matter of fierce debate, with activists pointing the finger upstream to China`s hydropower dams, which they believe channel water away from the upper reaches of the Mekong.
Pianporn Deetes, of campaign group International Rivers, said water levels were not just dropping but "fluctuating unnaturally", and that disruption to the ecosystem began after China built its first dam more than a decade ago.
"Local people experienced the loss of fish catch, the destruction of aquatic resources," the Thai environmentalist told a recent forum in Bangkok.
With a dozen dams proposed downstream as well as in China, she said locals were "worrying about the threats to the ecosystem, the livelihoods and food security. Definitely the impact on fisheries is our main concern".
China, which has eight existing or planned dams on the mainstream river, insists that extreme dry weather conditions are to blame for the current shortage – a claim backed up by findings of the intergovernmental MRC.
Whatever the reason, the problem concerns more than 60 million people who live in the lower Mekong basin and normally each eat 30 to 40 kilograms of fish every year, according to an MRC report released on Saturday.
People in southern Laos, for example, have relied "for generations" on diverse aquatic life for high-protein diets and have livelihoods "closely entwined with the seasonal rhythm of the river", the report said.
The abnormally low levels are disrupting the vast fishery, raising fears over already endangered species such as the Mekong giant catfish that can weigh up to 350 kilograms, said MRC spokesman Damian Kean.
A shallower river can affect breeding and migration patterns, as well as the waterway`s general ecological health, he said.
The MRC report urged caution over future developments in the basin, warning of dangers posed by both proposed dams and expanding populations.
"Over the past five years, significant changes have taken place in water-related resources and this is likely to continue, which may put livelihoods under threat," said commission adviser Hanne Bach.
The drought and dam debate were set to dominate an MRC summit in Thailand on management of the river starting Sunday attended by the leaders of Laos, Cambodia, Vietnam and Thailand, along with ministers from China and Myanmar.
Urgent action is needed to protect the Mekong basin "before it`s too late," said campaigner Pianporn.