Environmental and Economic Importance of the Tonlé Sap
Fisheries across Southeast Asia produce upwards of 20% of the world’s fish supply as of 2020. One waterway of economic and cultural significance is the Tonlé Sap lake and tributaries, which flow centrally through Cambodia, and provide the country with its second most relied-on food: fish. The Tonlé Sap's waterways are crucial to the Cambodian economy as they support a rich fishing industry, which provides a primary source of income and food for ~1.2 million people that live in the surrounding region.
“Tonlé Sap” translates in Khmer to “fresh water”, or “great lake”, which is fitting considering that it is the largest freshwater lake in Southeast Asia. As part of the Mekong river system, it is one of the most diverse and productive ecosystems in the world, providing over 60% of the entire country’s population’s protein intake. Through a flood pulse system, the directional flow of the river changes twice annually, supplying the lake and the Mekong tributaries with water at different times of the year.
Tonlé Fisheries Face Threats
The Tonlé Sap Lake and its fisheries are becoming increasingly endangered by large-scale foreign infrastructure projects funded primarily by China, such as upstream hydroelectric dams. These dams obstruct the vital sediment flow necessary for maintaining the river's flood pulse system, which is crucial for supporting aquatic ecosystems and fish populations. The Mekong River, which feeds into the Tonlé Sap, is also facing severe ecological threats, with one in five of its fish species now at risk of extinction.
Additionally, large-scale dam projects seem to compound the effects of the climate crisis: the period from 2019 to 2021 was the driest on record for the lake, exacerbating the strain on fish stocks as the usual early-season inflows—carrying essential sediment, larvae, and nutrients—were severely reduced. While the past two years have seen a return to more typical annual rainfall levels, the precipitation has been concentrated in the wet season, disrupting traditional flood patterns. The Mekong River Commission (MRC), the primary regional body responsible for coordinating water management and consulting on new dam projects, noted in 2020 that the delayed flood swell was partly due to reduced rainfall in 2019 and the operation of upstream dams in Laos and China. This minimum disruption of sediment flow threatens the health of the Mekong River and its tributaries, placing immense pressure on the Tonlé Sap's already vulnerable fisheries.
Historical Context of Cambodia
The historical context of land issues in present-day Cambodia is deeply rooted in the tumultuous events of the 1975-79 civil war under Pol Pot's regime, which disrupted property rights and land ownership on a wide scale. During this period, Pol Pot's government abolished private property and destroyed existing title deeds, resulting in widespread chaos and displacement when the regime fell in 1979. Cambodians, lacking formal land titles, settled wherever they could, leading to often-contested land ownership.
Since this period, there have been attempts by the government to remediate these problems. The 2001 Land Law aimed to address this issue by allowing individuals who had occupied land peacefully for at least five years to request definitive ownership titles; however, these titles were often only recognized at the local level, leaving many disputes unresolved.
In the late 2000s, the Cambodian government, pursuing modernization and economic growth, granted significant concessions to private companies—both Cambodian and foreign—for large-scale agricultural and industrial projects, which covered 12% of the country’s agricultural land by 2012, according to the local NGO Cambodian League for the Promotion and Defence of Human Rights. This shift has made traditional rice farming increasingly unsustainable for local farmers and their livelihoods. At the same time, land grabbing*, compounded by the legacies of civil war and poor land tenure systems, has displaced countless local farmers and fishermen. Between 2000 and 2023, over 170,000 households faced land disputes, with the international organization Global Diligence estimating around 830,000 affected individuals in the year 2015.
Despite these figures, the Cambodian government has often downplayed the scale of these issues, complicating efforts to address the profound impacts on local livelihoods and exacerbating the ongoing struggle for land and economic security, especially amongst rice farmers and fishing communities.
* Land grabbing is the large-scale acquisition of land through buying or leasing of large pieces of land by domestic and transnational corporations, governments, and individuals, often against the sovereignty and needs of local communities that steward or live off the land.
Fishing boats on Boribo river, a main tributary of the Tonlé Sap. Photo Credit: Lunas Global Health
Current Conditions of Tonlé Sap Communities
The conditions of communities around Tonlé Sap Lake are increasingly precarious as they face displacement from their traditional fishing livelihoods due to the combined impacts of the climate crisis and large-scale infrastructure projects. Tonlé Sap, renowned for having the world’s fourth-largest inland fisheries production, is experiencing a significant decline in fish stocks as a result of overfishing, illegal fishing, and deteriorating water quality. Pollution from nitrogen and phosphate runoff, inadequate waste management, and the effects of industrial, agricultural, and livestock sectors have severely compromised fish health and water quality.
As fishing yields diminish, many fishermen from floating villages are forced to migrate to pursue jobs in agriculture, a sector also struggling due to fluctuating prices, droughts, and extreme heat. For example, in Baribour District, Kampong Chhnang Province, traditionally a rice farming area dependent on seasonal Tonlé Sap flows, small-holder farmers are finding it increasingly difficult to sustain their livelihoods, and are forced to look for jobs in the urban areas or to immigrate to other nearby countries like South Korea and Thailand.
The environmental and economic stresses have exacerbated food insecurity and driven families still located around the lake into debt. The increased intensity and length of the dry season, compounded by El Niño effects, have further disrupted agricultural practices, causing irregular planting and harvesting, deteriorating water supplies, and posing severe health risks. With temperatures soaring between 40-45°C (104-113°F) and insufficient cooling measures, communities are suffering from heat-related health issues, including heatstroke and dehydration. This confluence of ecological degradation and health challenges underscores the conditions faced by those around Tonlé Sap Lake, revealing how environmental and health crises exacerbate the vulnerability of these communities.
Protecting Fisheries and Livelihood
The quality of life for Tonlé Lake and its communities points to a future of uncertainty– populations living around other regional waterways have already started to experience mass displacement at the hands of Cambodia’s elite. While fishing communities endure the loss of traditional livelihoods due to aggressive development and privatization, many take up the fight to confront the government and business elite. For example, Lake Boeung Tamok, which once supported thousands of fisherpeople and farmers with its shallow waters ideal for fishing and cultivating aquatic plants significant to local cuisine, has been nearly completely filled in—approximately 75 percent of its 3,240 hectares—to make way for upscale private residences for Cambodia’s elite.
Activists like Sueun Sreysok, who protested to protect her property, have faced severe repercussions, including charges of “intentional violence against authority” and judicial supervision, while her neighbor Prak Sophea fled to Thailand to escape arrest. Sreysok has continued to highlight the disparity, stating, “For the rich, these waters are not a source of livelihood, as they are for me. But in Cambodia, development never benefits the poorest.”
Other environmental activists who have successfully challenged harmful projects, such as the Chinese-led hydroelectric dam threatening an Indigenous community and the corrupt sand export industry destroying local ecosystems in Koh Kong, have been sentenced to 6 to 8 years in prison. This pattern of state repression against those advocating for environmental and human rights is a familiar response from those in power– similar instances of repression are common in neighboring countries like the Philippines.
Future for Tonlé Communities
The future of Tonlé Sap Lake is similarly shaped by the impacts of conflicting conservation efforts, exacerbated by privatization and foreign interests. Cambodian politicians have prioritized selling land to foreign investors and approving infrastructure projects like roads, skyscrapers, giant malls, and mega-dams that do not benefit local communities. In the instance of the Tonlé, this rhetoric of development is also implemented in the rapid and poorly integrated conservation policies.
Around the Tonlé, rice is a significant cash crop. Rice farming is water intensive, so farmers use fertilizers and pesticides that further pollute the lake– innovation here is non-existent because farmers are often in debt. Meanwhile, the conservation plan which splits up farming land into three designated zones (developed in 2011) was not enforced until 2021 by President Hun Sen. Outlined objectives included sustaining the waterway by decreasing the amount of land usage for small-scale farming, instead turning the water into clean energy power for mega-dams. The government policy has stated that the conservation efforts would also improve the economy, because former farming communities would enter the workforce in new and diverse industries. These conservation measures have clashed with the realities faced by communities that have relied on the lake for generations.
Despite the accompanying narrative of “few farmers, more diverse economy”, the cities lack the necessary economic infrastructure to absorb these displaced populations. Additionally, there has not been much support for affected families: no subsidies for lost land, and no compensation for land titles in conservation zones. The ongoing land sales and environmental degradation driven by foreign interests undermine the efficacy of conservation efforts, suggesting that without addressing these broader systemic issues, conservation will remain a futile endeavor, perpetuating the displacement of vulnerable communities and the degradation of Tonlé Sap's ecosystem.
“Subsistence farmers like Yi and Keo have little impact on the health of Tonlé Sap, compared to other environmental stressors on the lake like industrial pollution, overfishing and climate change”, says Laurie Parsons, a senior lecturer in human geography at Royal Holloway, University of London. “The government and industry have competing economic interests on the lake and waterways, which contradict their own conservation efforts. Sand dredgers continue to have unfettered access to the water, and dams upstream in Laos and China restrict water and sediment flow to the Mekong Delta.”
“If dams continue to be built, and the climate change predictions happen, and sand mining continues,” Brian Eyler, Southeast Asia program director for the U.S.-based Stimson Center, “all the efforts to conserve the resources are going to be for naught.”
This situation is compounded by industrial pollution, overfishing, and climate change, which overshadow the impact of subsistence farmers on the lake's health.
Implications for Developing Countries: South & Southeast Asia
The Tonlé Sap Lake and its tributaries in Cambodia can serve as a critical case study for communities in other developing countries in Asia and beyond that are forced to confront the impacts of neoliberal policies. As the climate crisis intensifies, the countries that contribute the least to global carbon emissions, including Cambodia, are among the most severely affected. Extractive industries exploit these nations' natural resources for energy and economic gain. Cambodia, a country still recovering from the devastation of over two decades of civil war and genocide, is particularly vulnerable due to its underdeveloped infrastructure and the government’s strong desire for rapid development. This pursuit of profit is marred by poor waste management, inadequate irrigation, and unsustainable agricultural practices, leading to the degradation of the Tonlé Sap ecosystem. Moreover, the construction of hydropower dams along the Mekong River by Chinese companies disrupts the vital flood pulse system that supports the lake's biodiversity.
In their bid for development, the Cambodian government, in collaboration with transnational corporations, often displaces local communities from their lands and waters, stripping them of their traditional fishing and farming livelihoods. With limited opportunities in an under-industrialized economy, these communities face worsening conditions due to more intense wet seasons, destructive monsoons, and declining fisheries, which in turn adversely affect public health. The situation in Cambodia highlights the broader challenges faced by Southeast Asian nations and other tropical climate regions where the relationship between climate vulnerability, resource exploitation, and development policies threatens both environmental and human well-being.
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