One after another, dorsal fins crest above the Mekong river waters. Under the piercing noon sun of February, three small boats turn off their motors to bob on the water. Around a half-dozen Cambodian tourists wait quietly aboard each vessel, squinting and pointing where they see a dolphin rise above the reflected sunlight.

This 60m-deep stretch of the river in Cambodia’s Kratie province, named after the Kampi rapids just upstream, is one of three deep pools that are home to the Mekong’s last surviving population of Irrawaddy dolphins. Fewer than 90 adults still live in the river, their existence threatened by fishing nets, dams and other human developments.

The current range of the Irrawaddy dolphin in Cambodia. Map by The Third Pole

Sor Chamroeun, a river patroller employed by the Cambodian government, recalls that when he was young, dolphins ruled this stretch of the river. “In the 1970s, after the Khmer Rouge, there were thousands of dolphins,” he said.

Those days are gone on the Mekong. On February 20, the last Irrawaddy dolphin in the Chheu Teal pool – on the Laos-Cambodia border some 70 km north of the Kampi pool – was found dead, spelling their extinction in Laos. In Cambodia, conserving and even counting the surviving dolphins remains a difficult task.

Disappearing river dolphins

The rotund, slate grey Irrawaddy dolphin is native to both salt and freshwater habitats from eastern India to Borneo. The species is globally endangered, while the three subpopulations surviving in rivers – the Irrawaddy in Myanmar, the Mahakam in Indonesia’s East Kalimantan province and Cambodia’s stretch of the Mekong – are regarded as critically endangered, numbering an estimated 250 dolphins in total in 2020.

Tourists set off to view dolphins in Cambodia’s Kampi pool, part of a 180km stretch of the Mekong River within which the dolphins enjoy some protections. Photo credit: Thomas Cristofoletti / Ruom

Cambodia counted 89 adult Irrawaddy dolphins in the 85-hectare area of the Mekong in Kratie province, according to a 2020 census presented at the latest tri-national workshop on the species, attended by officials and scientists from Myanmar, Indonesia and Cambodia. This represents a fall from an estimated 200 in 1997.

Mok Ponlok, director of Kratie province’s fishery department, told The Third Pole that the dolphins’ behaviour and distribution have been changing in recent years. They previously moved between the area’s three deep pools at Koh Pdao, Koh Ro Ngeav and Kampi, but in recent years, more seem to spending most of their time in the Kampi pool, he said.

“I think it’s because the Kampi pool has more food, also it’s deeper, [so] that is why those dolphins move to Kampi during the dry season until the rainy season,” he said.

Illegal fishing

Ouk Vibol, head of fisheries conservation for Cambodia’s Ministry of Agriculture, Forestry, and Fisheries, told The Third Pole that almost all deaths of the dolphins in Cambodia have been attributed to illegal fishing, although it is not always easy to tell for sure. Dolphins drown after being caught in gill nets (vertical panels of netting set across a stretch of water), or are lethally injured by electrofishing (the use of electric shocks to stun fish that can then be collected).

Gill nets can also injure the dolphins or wrap around parts of their bodies inhibiting their movements. Both these things can make it harder for them to hunt and lead to their eventual death, Vibol said.

Electrofishing tools confiscated by Mekong River patrollers. Electrofishing is banned across Cambodia, but the use of gill nets – another significant threat to the river’s Irrawaddy dolphins – is only illegal in protected core habitat zones, which makes the practice harder to prevent. Photo credit: Thomas Cristofoletti / Ruom

Electrofishing is banned throughout Cambodia, but gill nets are only prohibited within protected core habitat zones along a 180km stretch of the river in Kratie and Stung Treng provinces, established in 2012 to conserve the dolphins. The fisheries department employs 72 river guards to patrol the Mekong and try to stop fishers from using illegal methods. The depth of the Kampi pool helps shelter the mammals from fishers’ nets, but they are more vulnerable when they enter surrounding waters.

Kratie fisheries director Ponlok said patrollers are generally concentrated around the Kampi pool, following the dolphins’ behaviour patterns. But illegal fishers are observant and react to the patrols’ habits, limited numbers and lack of equipment.

“The illegal fishers only act when they see our river patrols take a break,” he said. “We work hard to crack down on illegal fishing by rotating the patrols [through] the day and night. Still, there are illegal fishing cases committed every day.”

At the Kampi river guard station, a sparse room on the river shore with an encyclopaedia of faded river maps and fish identification posters, patroller Kem Sophat explains the dangers of their antagonists and the water itself.

“We have gone to confront [illegal fishers] and ended up in a fight on the boat,” he said. “The illegal fishers attack us. If we go with too few guards, they will attack us and only let go when more of us arrive at the scene.”

River guards get ready for a patrol of the Kampi pool. It is a dangerous job – this stretch of the Mekong is difficult to navigate, and the patrols face regular fights with illegal fishers. Photo credit: © Thomas Cristofoletti / Ruom

The Mekong in Kratie is tricky to navigate, with rapids as well as dense clusters of rock hidden underwater. Sophat told The Third Pole that one patroller died on the water last year when a sudden storm erupted and currents became too strong to navigate.

“The sky became dark suddenly, he could not act in time,” he said. “The storm came, followed by the waves. Nobody could have saved anybody. [He] was reaching for the tree branches, but he was submerged in the river.”

The trio of guards who met with The Third Pole complained about their low income, of between $100 to $150 per month, adding they used their own boats for patrols. “If we take time to do something else, we could earn even more. It is out of the heart we keep doing this job,” patroller Chamroeun said.

In response to patrollers’ concerns about their low income, Vibol said that his fisheries conservation department provides support for gasoline and meals, but admitted some boats could use upgrading.

Even with their limited resources, in the last year patrollers in Kratie province managed to record 187 cases of illegal fishing and confiscate 35,760 metres of gill nets used in the protected zones. This is a decrease from 234 cases in 2020, but Ponlok said only two cases of illegal fishing were prosecuted in court in each year.

A young fisher lays a gill net in the Chheu Teal pool on the Laos-Cambodia border. The pool’s last dolphin died earlier this year with netting wrapped around its tail. Photo credit: © Thomas Cristofoletti / Ruom

Vibol told The Third Pole that the patrollers’ struggle against illegal fishers has been partly limited by the law. Gill nets in particular are still permitted outside the protected habitat zones set up in 2012. In addition, even if a patroller catches a fisher with banned nets or electrofishing equipment, it is easy for the culprits to abandon this evidence in the currents, making them hard to prosecute, said Vibol.

Dams to disease

Illegal fishing is not the only threat facing Cambodia’s last dolphins. Vibol told The Third Pole that the decline of the transboundary Chheu Teal population corresponded with the 2020 start of operations of the Don Sahong hydropower dam, around 2km away from the pool.

The construction and operation of the Don Sahong dam corresponded with a decline in the population of Irrawaddy dolphins living in the Chheu Teal pool just to the south. Photo credit: © Thomas Cristofoletti / Ruom
Increased noise and sediment pollution during the dam’s construction made it harder for the dolphins to find food, and pushed them out of their protected pool. Photo credit: © Thomas Cristofoletti / Ruom
River fish for sale in a market north of the Don Sahong dam in Laos. With the dam now in operation, the channel is blocked to fish moving upstream for breeding and spawning, impacting on local livelihoods. Photo credit: © Thomas Cristofoletti / Ruom

The Don Sahong dam is one of two operational dams on the mainstream of the Mekong in Laos. Seven more are in various stages of development, most with some level of Chinese involvement via wholly or partly state-owned enterprises in investment, construction, or development. Mainstream hydropower dams have been alleged to affect fisheries as far as the Mekong delta in Vietnam.

Seng Teak, country director for World Wide Fund for Nature Cambodia, told The Third Pole that the Don Sahong dam harms not just the dolphins but the broader transboundary ecosystem and fishers’ livelihoods, as it fully blocks the Don Sahong channel.

“[A] big number of fish that need to move upstream for breeding and spawning are unable to pass the dam barrier during the dry season,” he said in a written response. “This leads to reduced fish stock in the transboundary deep pool habitats that would affect dolphin prey and have affected daily food consumption of people of both countries.”

Additional impacts on the deep pool ecosystems range from a higher algal concentration that is likely connected to declining fish populations to a reduction in their depth caused by increased sediment flow during the dam’s construction, said Teak.

Far downstream of the Don Sahong dam, Vibol said that mainstream hydropower dams have affected the whole Cambodian dolphin population by changing the river flow and upsetting the food chain. “It does not cause direct [death] to dolphins but changes the fish that are the prey of dolphins,” he said.

A 2009 World Wide Fund for Nature report based on samples from dead Mekong dolphins identified bacterial disease as a significant cause of death, exacerbated by environmental contaminants such as mercury and pesticides, likely seeping into the Mekong from gold mining and agriculture respectively, which weaken the dolphins’ immune systems. Recent studies have highlighted high mortality among calves: the 2020 workshop report notes that half of the eight newborn calves recorded on the Mekong in 2020 died, with the causes unclear.

A World Wide Fund for Nature team perform an autopsy on an Irrawaddy dolphin found dead in Kampi in 2018. They determined the cause of death to be bruising from an illegal fishing net. Photo credit: © Thomas Cristofoletti / Ruom
Samples taken during the autopsy. World Wide Fund for Nature has found that bacterial disease and environmental contaminants are also significant causes of death for the Mekong’s dolphins. Photo credit: © Thomas Cristofoletti / Ruom

A 2018 study looking at genetic samples from Mekong dolphins estimated the population is just 5.2% of its ancestral size and continues to decline, both in numbers and genetic diversity. This limited gene pool puts the dolphins at risk of issues such as problematic mutations and inability to adapt to change, which the report said were “correlated with the risk of extinction”.

Saving last dolphins

For about a month before the death of the last dolphin in the Chheu Teal pool, patrollers noticed a piece of gill net wrapped around its tail. Nobody had seen the dolphin tangled in a net, said Vipol, so it was not clear whether Cambodian or Lao fishers were responsible.

He added that the pool’s location along two countries’ borders had made it harder to decide what actions to take to protect the shrinking population, which had steadily declined from eight adult dolphins in 2007, to three in 2018 and one remaining by October 2021.

The tail of the Irrawaddy dolphin found dead in 2018 was wrapped in netting. Gill nets are banned in the Kampi pool, but their use is hard to control, and when fishers are caught with them, they often dump them in the river to avoid prosecution. Photo credit: © Thomas Cristofoletti / Ruom

With the Mekong’s last surviving dolphins now all within Cambodia’s borders, Vibol said the fisheries ministry was galvanising efforts to protect them. His department has budget to start building a floating patrol station near the Kampi pool this year, he said. In addition, the ministry has submitted a new law on fisheries to the Interior Ministry for review, which among other policies includes stricter punishments for those caught using banned fishing tactics.

“We expect when we have the new law, we should have stronger [enforcement] in terms of penalties for illegal persons who use electrofishing or sharp gill nets,” he said, though he declined to provide an example of stronger punishments since the draft law is under review.

When asked whether the government would consider a national ban on gill nets, Vibol deflected, saying the nets were useful for catching other fish species. He said fisheries officials have started educating those caught fishing with gill nets on why they should not be used in the protected fishing areas, adding that no one wants to be caught killing a dolphin.

“We try to explain to [the community] about the death of dolphins caused by gill nets,” he said. Citing the potential of ecotourism, he added: “It is the most important aquatic animal, and local people can benefit from dolphins… If the dolphins go away from our Mekong, we will suffer.”

The remains of an Irrawaddy dolphin garlanded with plastic flowers in a small temple on an island in Stung Treng province. The dolphin is regarded as sacred in Cambodia, with various myths describing how the mammal was originally a woman who threw herself into the river to escape marriage to a snake. Photo credit: © Thomas Cristofoletti / Ruom

Like river patroller Chamroeun in Kratie province, Kong Chanty, head of Stung Treng province’s O’Svay fishing community along the Lao border, said he remembers the days when Irrawaddy dolphins swam all the way down the Mekong to its intersection with the Tonle Sap River in Phnom Penh.

With the dolphins now extinct in his area, he mourns for them. “The dolphin was part of the community,” he said. When the last dolphin died, an official suggested building a monument in Stung Treng province, but Chanty feels that legacy could not compare to seeing living dolphins in the Mekong. “The identity of this place as the habitat of the dolphin will stay, but the dolphin is gone. Who would want that?”

This article first appeared on The Third Pole.