<p>A family separate their catch of shrimps, crabs and fish from the mangrove leaves that fall into their pond. They practice a more sustainable form of aquaculture, where at least half their land is covered by mangroves. However, one downside of this, says shrimp farmer Tran Van Thac, is that the mangrove leaves change the pH levels of the water, which can affect his shrimp. (Image: Thanh Nguyen / The Third Pole)<br />
HL: Shrimp farmers’</p>

Mekong Delta shrimp farmers’ enthusiasm for working with mangroves is waning

Leaving space for mangroves among the shrimp farms of Vietnam’s Mekong Delta has been a win-win for aquaculture and the environment, but farmers say the economic benefits of the model are slowing

Under a canopy of mangroves, Tran Van Thac’s black tiger shrimps scuttle about the clean waters of their pond, devouring any organic matter they encounter. For years, ‘integrated shrimp-mangrove’ ponds like Thac’s in the southern Vietnamese province of Ca Mau, on the Mekong Delta, have been praised for providing organic produce and stable yields at a low cost, while allowing mangroves to be preserved.

But this year, the harvest from Thac’s 10-hectare pond is down. The 49-year-old farmer blames recent strange weather, which he says he hasn’t experienced in his 30 years of shrimp farming. Unexpected rains during the December-May dry season have diluted the brackish water the shrimp need, and colder than usual temperatures have made it hard for them to survive.

“They have to hibernate in the mud for weeks,” he says. “[They] hardly eat anything while suffocating in the freshwater. Most die before reaching maturity.”

Mangrove trees in shrimp ponds in Vien An commune, Ngoc Hien district, Ca Mau province
Mangrove trees growing in shrimp ponds in Vien An commune, Ca Mau province, in southern Vietnam (Image: Thanh Nguyen / The Third Pole)
Nam Dzung circling his 8-ha pond by boat in Vien An Commune, Ngoc Hien, Ca Mau provine, Vietnam.
Phan Tien Dzung monitors his 8-hectare pond by boat in Vien An commune (Image: Thanh Nguyen / The Third Pole)
Bird's-eye view of sustainable shrimp-mangrove farms in Vien An Commune, Ngoc Hien District, Ca Mau Province, Vietnam.
Integrated shrimp-mangrove farms in Vien An commune, in Vietnam’s Mekong Delta, in March 2023. Vietnam’s forest protection policies require farmers to leave a minimum of 50% mangrove coverage – a proportion also required by sustainable seafood companies. (Image: Thanh Nguyen / The Third Pole)

Thac is signed up to an organic programme with a major seafood producer, under which farmers are not allowed to add fertiliser, antibiotics, growth promoters or other chemicals to the water. “Our shrimp, crabs, fish and our mangroves rely 100% on the environment,” he says. “And when it changes, it messes up everything and our hands are tied.”

Sunny and alluvium-rich, Ca Mau province is home to Vietnam’s largest area of mangrove forest, with 69,000 hectares of the climate change-combatting vegetation. Ca Mau is also the shrimp capital of the country, with more than 278,000 hectares of shrimp ponds.

Instead of replacing forests to make way for ponds, integrated shrimp-mangrove farming spares at least half of the area for rhizophora trees – the native tropical mangroves. In turn, the trees provide nutrients, nurseries and breeding grounds for shrimp, crabs, and fish.

Thac and his father pulled a funnel-shaped net of about 2-3m long to harvest the shrimps on the evening of March 22
Having drained the water from their pond earlier in the day, Tran Van Thac and his father harvest their shrimp on the evening of 22 March (Image: Thanh Nguyen / The Third Pole)
Each of these black tiger shrimps weighed around 500gram, fed purely with natural food sources in the ponds.
Thac’s black tiger shrimps feed only on material that occurs naturally in his ponds. The shrimp larvae are released between September and December. (Image: Thanh Nguyen / The Third Pole)
Thac added crabs and fish in the ponds’ habitat to “ensure some certain balance in their local ecology.”
 Thac adds crabs and fish to the ponds to ‘ensure some certain balance in their local ecology’ (Image: Thanh Nguyen / The Third Pole)

Ordinarily, within three to four months the system yields organic, healthy shrimp. These fetch higher prices than conventionally produced shrimp, at up to USD 13 per kilogram, and are in demand in foreign markets like the European Union. With 23,000 hectares occupied by integrated shrimp-mangrove farming, Thac’s home district of Ngoc Hien is where the system is most widely used.

On paper, it’s a win-win: mangroves are saved, and farmers’ incomes are boosted. The rate of mangrove loss due to aquaculture in the Mekong Delta has fallen, from 2,440 hectares a year between 1973 and 1990 to 1,490 hectares a year between 2010 and 2020.

But a closer look at this mangrove stronghold in the world’s thirdlargest delta reveals a more complex picture. Despite the benefits of the integrated shrimp-mangrove model, tension remains between the needs of the forest and the aquaculture industry – and this is being aggravated by both climate change and the effects of upstream dams.

‘Mangroves are still underappreciated’

Most of the land of the Mekong Delta owes its existence to mangroves. Their roots trap sediment as the Mekong River pours into the South China Sea, and so layers of silt are deposited in the brackish water. Mangroves also play a crucial role in carbon capture: globally they account for about 3% of all carbon stored by tropical forests.

“It’s a magical tree that can digest salty water and dirty air and thrive,” says Vo Quoc Tuan, a mangrove specialist at Can Tho University. “Mangroves have been and are still being underappreciated, not just by farmers but also the general public and… the government.”

The loss of Vietnam’s mangroves started in earnest with the thinning of the forests by 19th-century French colonisers. During the Vietnam War, the use of defoliant chemicals destroyed more than 40% of southern Vietnam’s remaining mangroves.

Then, beginning in the 1980s, the government, World Bank and Asian Development Bank encouraged the conversion of mangroves to shrimp ponds as a way to reduce poverty and grow the economy. In parts of the Mekong Delta, the area covered by shrimp ponds increased by 20 times between 1980 and 1993.

Traffic in a canal on the fringe of the Ca Mau Cape National Park.
Houses flanking a canal on the fringes of Ca Mau Cape National Park, a protected area where afforestation projects are ongoing (Image: Thanh Nguyen / The Third Pole)

Between 1996 and 2010, Southeast Asia lost a greater proportion of its mangroves than anywhere else in the world.

According to government data, as of 2020 Vietnam only had around 238,000 hectares of mangrove cover left. Researchers who analysed satellite images in 2020 identified 102,160 hectares remaining in the Mekong Delta, while another survey conducted in 2018 painted an even bleaker picture, of just 73,000 hectares remaining in the region.

The picture might yet be worse were it not for efforts, starting in the 1990s and ramping up in the 2010s, to protect and restore Vietnam’s mangroves. Land was allocated for replanting mangroves, and areas such as the core zone of Ca Mau Cape National Park were put under stricter protection.

Tourists in Ca Mau Cape National Park, a wetland designated as of international importance under the Ramsar Convention
Tourists in Ca Mau Cape National Park, a wetland designated as of international importance under the Ramsar Convention (Image: Thanh Nguyen / The Third Pole)

“Our findings show that the conversion is not happening so much now,” says researcher Vo Quoc Tuan. “If you look at the inland mangroves from the remote sensing, the total area is even expanding – not as fast as it should be – but still good news.” Tuan attributes much of this improvement to integrated shrimp-mangrove systems.

While the efforts of the government and international organisations have reduced the area of forest being converted, mangroves are still being lost. Sea level rise, landslides, pollution and the operations of hydropower dams upstream have all led to mangroves retreating inland. In recent decades, precipitation during the rainy season has become heavier and more frequent, but it has reduced during the dry season. As a result, overall the brackish water of the Mekong Delta has become saltier and less conducive to mangrove seedling survival and growth.

Abandoned houses in a hamlet in Ngoc Hien district, Ca Mau. Coastal erosion is affecting both mangroves and people’s livelihoods in this area.
Abandoned houses in a hamlet in Ngoc Hien district, Ca Mau. Coastal erosion is affecting both mangroves and people’s livelihoods in this area. (Image: Thanh Nguyen / The Third Pole)

On top of this, farmers are increasingly questioning the benefits of integrated shrimp-mangrove farming.

Growing scepticism of the mangrove-shrimp model

Phan Tien Dzung was one of the first farmers to sign up to an initiative which promoted the coexistence of shrimp farming and mangroves.

Arriving in Ca Mau from northern Vietnam amid the ‘shrimp fever’ of the late 1980s, he started by chopping down mangroves and digging out ponds on 8 hectares of land.

“Forest land was allotted to people willing to make a living out of it or sold at a cheap price,” the 64-year-old recalls. “For shrimp, you just led the river water into the ponds, which were already full of larvae, and waited three months to harvest lots of them. Everything was so abundant and easy to get back then.”

High shrimp yields in those first few years helped him to build a comfortable life and a spacious house in Vien An commune, in the zone surrounding the strictly protected Ca Mau Cape National Park. Then, he says, “in 1994 forestry officials came to the village and asked us to spare half of our pond area to grow mangroves”.

Mangrove coverage policies and shrimp certification schemes in the Mekong Delta

Starting in 1995, mangrove coverage ratios began to be enforced under official forest protection policies in Vietnam: to be granted land in mangrove areas, farmers had to sign contracts with local forestry management boards or state-owned forestry companies.

The ratio of mangrove-to-pond coverage currently varies between provinces and the type of forest land being allotted. Researchers have said optimum results are achieved when mangroves cover roughly 60% of a plot of land, but generally policies stipulate a minimum mangrove coverage of 50%. Seafood companies and NGO certification programmes require a similar ratio for shrimps to be labelled sustainable.

One such programme is an organic shrimp farming certification project called Mangroves and Markets (MAM), rolled out 2014 in Ca Mau by the International Union for Conservation of Nature (IUCN) and SNV Netherlands Development Organisation. This requires farms to have mangrove cover of 50%-60%, in return promising that they will be paid more for their produce.

The mixed shrimp-mangrove systems were promoted as a ‘win-win’: the mangroves would help to purify the water, creating an environment in which the shrimp could thrive, and in turn provide stable incomes for farmers. Farmers could also cut down the mangroves when fully grown, to sell their timber as an additional source of income.

For all the policy’s touted benefits, “people were not so fond of it”, Dzung says, but “had to go along if we wanted to keep making a living here”.

Dzung says that mangrove trees shedding their leaves into his ponds alters their condition. Mangrove leaves contain tannic acid, which can change the water’s pH levels. When the water conditions change due to this or after heavy rainfall, the shrimp die, he says. “It’s not like they all belly up at once in the ponds. Not so dramatic. They just vanish.”

Le Van Tan (sitting), a trader in Ngoc Hien District weighed Thac’s catches in the following morning
Le Van Tan (right, seated), a trader in Ngoc Hien district, weighs Thac’s catch from the previous evening. Thac receives about 570,000 Vietnamese dong (USD 25) for his organic black tiger shrimps. (Image: Thanh Nguyen / The Third Pole)

There have also been recent price fluctuations in the shrimp market, which Dzung says means that “traders paid us [organic farmers] sometimes as low as the industrial farms”.

And unlike shrimp, whose fast growth allows his family to cash in every three months, mangroves take at least 10 years to reach the ideal 12-cm diameter to harvest for timber – adding to his pessimism about the model.

“I understand the reasons for the trees to be here, protecting us from the storms and all kinds of climate turbulence,” the veteran farmer adds. “But people need to eat, they need their next meal secured.”

His sentiments echo a 2021 study which found that while local communities are aware of the benefits mangroves bring, the integrated shrimp-mangrove systems still stand on shaky ground in terms of support from farmers. Back at Vo Quoc Tuan’s lab in Can Tho University, the researcher sums up the situation. “Very few [farms] at the moment actually reach 50% [mangrove coverage],” he says. “Looking from above, you can see the dark green streaks of mangroves are very small. Meaning many shrimp farms have a tree ratio of only 30-40%, even lower sometimes.”

Researcher Vo Quoc Tuan points to a map on a computer screen, explaining what remote sensing data shows about mangrove coverage in the Mekong Delta
Researcher Vo Quoc Tuan explains what remote sensing data shows about mangrove coverage in the Mekong Delta (Image: Thanh Nguyen / The Third Pole)
Dutch expert in natural resources management Iris van Duren, who partnered with Tuan to research sustainable shrimp farming in the Mekong Delta
Dutch expert in natural resources management Iris van Duren, who partnered with Tuan to research sustainable shrimp farming in the Mekong Delta (Image: Thanh Nguyen / The Third Pole)
A comparison shot between the natural mangrove preservation zone (L) in the Ca Mau Cape National Park and one of the farms following the integrate shrimp-mangroves systems
Mangrove forest in Ca Mau Cape National Park adjoining farms using integrated shrimp-mangrove systems (Image: Thanh Nguyen / The Third Pole)

This lower ratio of mangrove coverage promises higher shrimp yields in the short term, but means a reduction in the ecosystem services the trees provide, in the long term reducing the farms’ productivity.

Money and community engagement needed

Vietnam, which is among the most vulnerable countries in the world to extreme weather, has committed under the Paris Agreement on climate change to restore and expand its mangroves. However, its Nationally Determined Contribution from 2022 – its national climate pledge under the agreement – notes that Vietnam only achieved about 30% of the target it was supposed to have reached in 2020 to protect, restore and plant mangroves and coastal forests.

“It’s a bumpy road, but there’s always hope,” says Iris van Duren, a Dutch expert on wetland ecology who has been working alongside Vo Quoc Tuan to raise awareness of the importance of mangroves and the integrated farming system for the Mekong Delta.

While there’s little Vietnam can do on its own to stop coastal erosion, given the impacts of dams and sand mining upstream on the Mekong, van Duren says integrated mangrove-shrimp aquaculture can be improved.

A newly-built shrimp-shaped guesthouse in the coastal area of Mui Ca Mau National Park
A new shrimp-shaped guesthouse on the coast of Ca Mau National Park, pictured in March 2023. There is potential for sustainable aquaculture to grow alongside community-based tourism in the Mekong Delta. (Image: Thanh Nguyen / The Third Pole)

First, van Duren points out, farmers will cut down mangroves if they can make profit from doing so. Research has found that rather than regulators taking punitive actions, offering farmers financial incentives to look after the mangroves on their land could be a more successful approach.

“Certification for truly sustainably produced shrimp could be a good start,” van Duren says. One problem certification schemes have run into is that travelling to farms to evaluate their mangrove coverage is expensive, labour-intensive and can lead to disputes with farmers.

Tuan and van Duren are working on a system that instead uses remote sensing technology and aerial photography. This can be used by companies and certification projects to accurately assess which farms in Vietnam meet their criteria.

Above all, however, Tuan and his team expect the data they gather to provide policymakers with “reliable and frequent information”, allowing more precise decisions when it comes to selecting sites and allocating funding for mangrove-restoration projects.

“You can alert them, for instance, if conservation areas are actually used for other purposes, or where dykes need to be built to protect people still living there, and where to leave [sites] for nature to do its job,” van Duren says.

Egrets perch on wooden fences, erected to protect mangrove saplings that have been planted in a coastal alluvial area of Ca Mau Cape National Park
Egrets perch on wooden fences, erected to protect mangrove saplings that have been planted in a coastal alluvial area of Ca Mau Cape National Park (Image: Thanh Nguyen / The Third Pole)

The growing market for forest carbon credits may help to drive this. As a pioneer of the UN’s REDD+ programme and the first country in Asia to initiate a nationwide scheme of payments for forest environmental services, Vietnam is now developing a domestic carbon market, scheduled to be in operation by 2028.

Tuan says that “[there] is still a long way to go” until such policies and their benefits trickle down from the central government to the Mekong Delta – “like the distance to the moon”. But to reach net zero by 2050, as Vietnam has pledged to do, he says this has to happen.

Arrow-shaped seedlings of the mangroves, which hang vertically to the ground. Once ripe, it dropped and speared the prospering mudflat below and grow a sapling.
Mangrove seedlings grow vertically down from trees, spearing the mud below when they fall (Image: Thanh Nguyen / The Third Pole)

In all of this, a vital missing ingredient for success is the voices and experiences of local communities. Despite their mixed feelings towards the mangroves in their farms, both Dzung and Thac are keenly aware that the southern tip of the Mekong Delta needs the trees to survive.

“But things need to be improved around here,” says Dzung, suggesting that officials could listen more to farmers’ concerns about poverty and food insecurity, and work alongside them more often.

Thac, meanwhile, is more concerned about the impact of the changing environment on his livelihood. “I heard mangroves help the world tackle climate change, yet we the growers here have already had to taste its impacts,” he says. “We’ve done our job of planting the trees – and can even plant more if they pay us well, but just us alone is not enough.”

Reporting for this story was supported by the Pulitzer Center’s Rainforest Journalism Fund