The Gulf of Thailand is teeming with seafood: mackerel, sardines, bream and squid. Snails and anchovies. Shiny green crabs and tiny pink shrimp.
“Every day, we are out catching fish and selling them,” says Khiev Sat, the longtime leader of the coastal Cambodian village of Koh Kresna and the patriarch of a large family of people who have fished for generations. As he speaks, his sister arrives on a bicycle loaded with the morning’s catch. “Our community fishery is strong,” Khiev says, smiling.
But it hasn’t always been this way. When Khiev was a young man, the waters near his home were largely empty. Around the world, coastal fishing communities still struggle with declining fish stocks as climate change, environmental degradation and overfishing decimate marine populations even as demand for seafood grows.
The key to Koh Kresna’s bountiful, sustainable fishery has little to do with the fish themselves and everything to do with one tree: the mangrove.
In many parts of the world, healthy fisheries rely on intact mangrove forests, says Radhika Bhargava Gajre, a coastal geographer and mangrove researcher at the National University of Singapore. “The majority of the fishes that we eat are supported by mangroves,” she explains, because the submerged roots act as a nursery for baby fish.
Mangroves are semiaquatic: they grow in water and very wet, salty soils where most plants can’t survive. Dozens of mangrove species exist, from bushy shrubs to full trees, but all have elaborate root systems that hold them steady against waves and wind. Those roots create sheltered, food-rich habitats that protect juveniles from predators and provide feeding grounds.
As a result, mangroves are a perfect place for aquatic animals to live, especially when they are young and vulnerable. Mangrove roots act as a nursery, supporting an estimated 800 billion young fish, prawns and crustaceans each year, according to a 2024 analysis by a coalition of governments and international biodiversity organizations.
But mangrove ecosystems face major threats. About half are at risk of collapse by 2050, the United Nations warns. They are cut down for aquaculture, logged for charcoal and cleared for coastal development. Pollution and rising sea levels add further stress. “If mangroves are not intact, then a big cyclone can come,” Bhargava Gajre says, and the weakened plants can be killed.
In Cambodia, political violence and mangrove destruction went hand in hand. The brutal Khmer Rouge regime of the late 1970s left the country’s economy in tatters; people had little to survive on and many cut mangroves for charcoal. Without those forests, there was no protection for young fish and local fisheries were decimated. Some people left for factory work or emigrated; villages shrank.
That decline prompted local education and action. Over the last three decades, scientists and international ecological organizations spread information about mangrove importance, and the message resonated with fishermen. Koh Kresna and the neighboring village of Lok set up a community fishery organization in 2003 to manage the nearby shallow waters and ensure sustainable harvesting. The fishery protects more than 145 acres of mangrove forest along its coastline.
They also replant. In the last two years, fishery members and local residents planted more than 2,000 mangrove saplings with support from international groups including the Red Cross and Landesa, a U.S.-based land rights organization. “It is a lot of work. It takes a lot of cooperation between the fishery members, the government and nongovernmental organizations,” says Rusrann Loeng, a fisheries expert who leads coastal projects in Cambodia for Landesa.
Cambodia’s work is part of a broader trend: since 2000, global mangrove decline has slowed as restoration efforts have ramped up. Net loss of mangroves decreased by 44% between 2010 and 2020 relative to the previous decade, a 2023 U.N. analysis found. “When it comes to conservation stories, you don’t come across lots of positive stories,” Bhargava Gajre says. The falling rate of mangrove deforestation is a rare example, and she credits community stewards like those in Cambodia.
Mangrove restoration has benefits beyond fisheries. Their roots stabilize soil and absorb wave energy, reducing erosion and the power of storm surge to protect inland areas. One study estimated that villages with more mangroves nearby had far fewer deaths from a major cyclone that hit India in 1999, showing how coastal forests can save lives as storms intensify with climate change.
Mangroves also trap planet-warming carbon effectively. Dead leaves and branches fall into the water and are buried in muddy soils, where they decompose very slowly compared to aboveground forests. As a result, mangrove forests can store up to four times as much carbon as other types of forests, one study found. Though mangroves make up just 0.2% of the world’s forest area, they account for about 2% of global forest carbon removal, according to a recent World Resources Institute analysis.
Those climate and safety benefits are well understood by people in Cambodia who have devoted careers to protecting and restoring mangroves. “We know this helps with climate change,” says 21-year-old Khiev Chien, a young member of the community fishery in Koh Kresna and the son of the town’s leader. “We are helping the whole world.”
For Koh Kresna, mangrove restoration translated into more fish in the water and more livelihoods on shore. The community’s coordinated protection, replanting and sustainable management show how local action can revive ecosystems and deliver benefits that reach far beyond a single coastline.