Bolivian communities fearful as river fish stranded
Communities in southern Bolivia's Tarija region rely heavily on fishing the Pilcomayo River. But as the BBC's Mattia Cabitza reports, irregular rains have led to a rapid build-up of sediment that has disrupted fish life cycles, putting livelihoods at risk.
It is the height of the fishing season in southern Bolivia, and dozens of men, women and children gather with much anticipation on the muddy banks of the Pilcomayo River.
With the help of a wooden boat and a couple of men up to their waists in water, people from Capirendita, a Weehnayek indigenous community, lay a long net across the whole width of the river.
In a matter of minutes, they start pulling on a rope and the net begins to emerge from the brown waters.
The eyes of the whole community scan over the net, laid flat on the river bank, in search of a bountiful catch in the mesh. But very few fish are flapping on the sandy bank.
"It's only five," says a man, after he has put them all inside a large fibre bag that is a stark reminder of how much they used to net.
"Last year, we were catching 10,000 a day," says Jose Segundo, a leader of the community of 220 families.
"But now, not even 1,000. They're not even enough to feed us."
His wife, Roxana Cabrera, looks out of their makeshift tent, her three young children beside her. She is also worried they can no longer make a living from fishing.
"Every time we lay the nets, it's just 10 or 15 fishes at most," she says.
"We now make no more than 10 bolivianos ($1.44, 80p). We used to make 300 bolivianos."
The Bolivian government has declared the Pilcomayo region a national disaster zone.
"We are living through a very critical time," says Alejandro Romero, of the National Technical Office of the Pilcomayo and Bermejo Rivers.
"We're seeing environmental degradation of considerable magnitude in the whole Pilcomayo basin."
Mr Romero explains that the river naturally carries up to 170m tonnes of sediment each year, which is deposited in the lower basin in neighbouring Paraguay and Argentina, where the Pilcomayo flows.
But in the last two years, a disrupted rainfall pattern in Bolivia, where the river rises, has accelerated the process of sedimentation, he says.
More intensive downpours mean that the river carries more water downstream at a higher velocity, causing faster erosion along its course.
This phenomenon, Mr Romero explains, creates larger than usual sand banks in the plains of Paraguay and Argentina.
The sediments there block the flow of the Pilcomayo after the rainy season, when it is natural for its volume of water to substantially decrease.
"There's a tract of the river that has seen a gradual build-up of sediments, and it is now blocked," says Mr Romero.
The tract he refers to is at the entrance of the Banado La Estrella, a huge swamp in the Formosa province of Argentina where the sabalo, the fish of the Pilcomayo, feeds and fattens.
Like salmon in North America and Europe, the sabalo, on which 6,000 families in Bolivia alone depend, swims upstream to spawn.
But because of the build-up of mud, it cannot complete its life cycle and reach its natural reproductive grounds in southern Bolivia.
"The situation of the indigenous people is very worrying," says Moises Sapiranda, the leader of Orcaweta, an organisation which groups together the 42 Weehnayek and Tapiete indigenous communities in Bolivia.
"We've depended on fishing for more than 500 years. It's the only food we've got during the fishing season," he says, referring to the period from 15 April to 15 September.
"If people don't fish, they go hungry and they migrate to other areas in search of work."
Because of the changing weather patterns, the Bolivian government fears the problem is likely to recur every year, and affect on a regular basis the 1.5 million people who live in the whole Pilcomayo basin.
"First of all, we need to do engineering work to guarantee a permanent constant flow of water," says Nelson Aguilar Rodriguez of the National Technical Office of the Pilcomayo and Bermejo Rivers.
"The other option is to build artificial lagoons in Bolivian territory so that we can have fish here," he says.
Such move would be unpopular with Bolivia's neighbours, because it would mean diverting water away from their agriculture and industry.
Bolivia recognises this would be a last resort. It wants Argentina to dredge the sediments on its tract of the river, so that the fish can swim upstream once again.
Argentina says it has begun doing this work, and that it will take weeks to finish.
But despite the assurances that Bolivia and its neighbours are doing all they can, people who depend on the river are far from satisfied.
"For us, the Pilcomayo is like a mother that gives us life," says Moises Sapiranda, the Orcaweta leader.
"Our people are now united and we will continue to pressure the authorities."
Mr Sapiranda says they will set up road blocks, and are ready to protest and keep on protesting until the problem is solved.