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Study: Fishing with pesticides and dynamite puts Ecuadorian Amazon in peril

People wait across the river to be picked up and brought to the community of Sinangoe the morning of the Constitutional Court hearing on November 15, 2021. Image courtesy of Kimberley Brown.

  • Illegal fishing with agrochemicals and explosives across several of Ecuador’s Amazonian states is an uncontrolled problem, causing long-lasting, irreversible damage to aquatic ecosystems, recent research has shown.
  • The study links high levels of poverty to the wider practice of unsustainable fishing, and calls for tighter controls on the sale and availability of agrochemicals and dynamite across the country.
  • Fish caught using toxic chemicals can be dangerous for human consumption, the study warns, and says there should be more action to help educate communities about these dangers.

In the Ecuadorian Amazon, uncontrolled illegal fishing with agrochemicals and explosives is causing long-lasting damage to aquatic ecosystems, while representing a real danger to human health, a recent study has shown.

The research points out that illegal fishing, poverty, and easy access to both agrochemicals and dynamite in the region are strongly linked. It calls on Ecuadorian authorities to regulate the use of toxins and educate communities about the dangers of illegal fishing.

For the study, the authors analyzed media stories of illegal fishing between 2003 and 2021 across Ecuador’s six Amazonian provinces — Sucumbíos, Orellana, Napo, Pastaza, Morona-Santiago and Zamora Chinchipe — and ran more than 100 surveys with groups including anglers, the environmental police, and local residents. Nearly half, 49%, knew about the illegal use of agrochemicals and dynamite in Amazonian fishing.

“Illegal and unsustainable fishing is widespread around all Ecuador, not only in the Amazon region,” says study lead author Ricardo Burgos-Morán, from Amazon State University in Pastaza. “People know it is a problem, but they can’t afford not to do it.”

Using natural toxins to fish

Ecuador and the wider Amazon region have a tradition of fishing with toxins using a resin called cubé, derived from the Lonchocarpus urucu plant, known locally as barbasco. Cubé resin contains a compound called rotenone, which, when diluted in water, attacks a fish’s respiratory system, causing it to drown.

This form of fishing is protected and permitted in many Indigenous areas and has traditionally been used to catch extra fish for festivals and celebrations. As such, it’s practiced by these communities only sporadically, and because rotenone degrades easily in water, it presents a low risk to the environment. However, there’s a rising fear that people outside of these communities are starting to use cubé indiscriminately, and catching more fish than they need.

River blast fishing practice.
River blast fishing practice. Image by Drajay1976 via Wikimedia Commons (CC BY-SA 3.0).

Preparing cubé is time-consuming, says Burgos-Morán, and large quantities are needed to have an effect. Agrochemicals, on the other hand, pack a more potent punch, with far more serious long-term and wide-ranging impacts.

The use of dynamite is a more targeted way of illegal fishing, and while less toxic than chemicals, its effects can be just as damaging, often destroying the riverbed and the underlying habitat.

According to Pedro Jiménez-Prado, a freshwater scientist at The Nature Conservancy Ecuador, of the three methods covered in the study, fishing with agrochemicals is the most serious because of “its high degree of toxicity and permanence in the environment but also the fact that it is not specific to the targeted species … It kills absolutely all living organisms.”

Environmental impacts include a decline in the natural fish population, as many of the chemicals include neuroendocrine disruptors, which can affect reproduction in fish and lead to an imbalance in the ratio of males to females. They can also cause mutations in amphibians and insects.

There’s also a fear of wider repercussions, said Jiménez-Prado, who wasn’t involved in the study, given that Ecuador accounts for only 2% of the Amazon Basin area, yet its patch of the rainforest is home to around 850 species of fish — as much as 30% of the total biodiversity of the entire Amazon.

“All this is of great importance if we also consider that the upper parts of two important tributaries of the Amazon — the basins of the Napo and Marañon — are in Ecuador and are the destination of many migratory fish that use their waters for reproduction,” Jiménez-Prado told Mongabay.

Fishing this way is also an issue for human health. “People don’t understand the dangers. They think that a simple wash is enough to clean the fish [of any residual chemicals],” Burgos-Morán said. “There is an enormous [knowledge] gap.”

He warned of the long-term effects of eating contaminated fish, such as learning problems in children, damage to the nervous system, liver problems, cancer, and anemia. “We need to monitor the long-term effects in local population,” he added.

Medardo Shiguango, head of the Kichwa People of Rukullakta (PKR), an Indigenous organization in Napo province, told Mongabay that most people resort to this type of fishing to feed their families, perhaps selling a small share of the catch to their neighbors. He said he believes people are aware of the risks, but often don’t understand how serious they are, which is why several people have died after eating contaminated fish.

Fishing with explosives and agrochemicals has far reaching environmental impacts on river biodiversity. Image courtesy of Amazon Watch.

Easy access to chemicals and dynamite

Agrochemicals and dynamite are widely available across the Ecuadorian Amazon, often bolstered by an illegal trade in pesticides and a proliferation of smuggled, counterfeit and adulterated products offered to farmers at lower prices.

In provinces such as Zamora Chinchipe, where the main economic activity is agroforestry centered on crops such as coffee, cassava and banana, the study shows the highest use of insecticides such as Palmarol and Methavin in fishing. In provinces such as Morona Santiago and Pastaza, where livestock ranching is more prevalent, there’s evidence of the greater use of Nuvan, a chemical used to kill lice in cattle.

However, despite the widespread use of these chemicals, they’re only used in small quantities, Burgos-Morán said, which means there’s no urgency yet for the agrochemical industry to become involved with education programs about their safe and legal use.

The study also shows that the problem of dynamite fishing has been exacerbated by changes to the law in Ecuador, which have left 99% of small-scale mining companies without permits. This has increased the quantity of explosives being smuggled into the country.

The study also linked illegal fishing to some of the poorest areas in Ecuador. “The more there is poverty, the greater the possibility of falling into … unsustainable fishing practices,” Burgos-Morán said.

The highest levels of poverty in Ecuador are found in the provinces of Morona Santiago and Napo, where fishing is a key source of food and protein. This, Burgos-Morán said, is one of the reasons why riverside communities are opting for nontraditional fishing methods.

“The sad thing is that it is the poor people that use this kind of fish catching,” he said, adding that while it may bring increased catches in the short term, it’s also “led to the decline of Amazonian rivers, impacting their diversity and environmental integrity.”

According to researchers, illegal fishing, poverty, and easy access to both agrochemicals and dynamite are strongly linked in Ecuador. Image by Elizabeth Anderson.

Need for greater government intervention

“The governments don’t know what is happening in the forest; it is so far away from where they are based. The environmental authorities lack the capacity to investigate,” Burgos-Morán said. People know they’re committing a crime, he added, but they know the chances of being caught and fined are very low, so the authorities need to be more present.

Ecuador is the only country in the Amazon Basin that doesn’t have a long-term monitoring program for fishing, he noted, even though it’s one the largest regional spawning grounds for migratory fishes. To start dealing with the problem, he said, there needs to be greater intervention from the authorities.

Burgos-Morán called for a stronger state presence in Ecuador’s rural hinterland, with more trained staff and more emphasis on education programs that teach people about the dangers of illegal fishing. At the same time, he added, conservation NGOs need to put more of their resources into protecting the Amazon’s water systems, as well as its forests.

Last year, for instance, The Nature Conservancy teamed up with the Ecuadorian government to establish five protected areas, covering a combined 100,000 hectares (247,000 acres) spanning the watersheds of the Chingual and Cofanes rivers. Both waterways are part of the network that feeds the Amazon. Ancestral claims by Indigenous peoples cover more than 60% of the Ecuadorian Amazon, and the region is important for water conservation and for maintaining connectivity between other areas of high biodiversity.

“The way to change these practices is to work with Indigenous communities, many of which have control over what happens on their land,” Jiménez-Prado said. Some already regulate their own fisheries and have banned the use of chemicals, he added: “They’re making decisions themselves.”

The next step, he said, “is to find common ground so that things can be replicated from one community to another.”


Burgos-Morán, R., Tillaguango-Jímenez, Y., Orellana-Medina, C., & Raju Maddela, N. (2023). Unsustainable fishing in Amazonian Ecuador involving agrochemicals and explosives detected by media surveys and stakeholder perception. Journal for Nature Conservation76, 126498. doi:10.1016/j.jnc.2023.126498

Banner image of a river in the Amazon by Kimberley Brown.

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