This Thai village created a tiny fish reserve years ago. Today, it's thriving.

In 1998, people in Na Doi, a quiet village in northwest Thailand, noticed that their fish catches in the nearby Ngao River were declining. The fish they did manage to net were also getting smaller. Together, Na Doi’s 75 households decided to try a radical solution: they would set aside a small stretch of river to be strictly off-limits to fishing.

Nearly a quarter-century later, the experiment has paid off. The protected section of the Ngao brims with large barb and mahseer (a kind of carp), and catches outside of the reserve, where the villagers fish, have significantly increased. The project’s shared ownership has created a greater sense of harmony and unity among villagers, and has benefited them individually, psychologically as well, says Nok Wa, 55, a farmer in Na Doi.

“Many times, when people in the village are upset, they go to watch the fish,” he says. “Sometimes the young children ask why we can’t eat those fish, and I tell them, ‘Our stomachs cannot eat those fish, but our eyes can still eat.’”

Na Doi was the second village in the Ngao River valley to adopt this pioneering approach to freshwater fisheries management. Since the late 1990s, at least 50 other villages there have done the same. As a whole, the entirely grassroots-led reserves have been stunningly successful, according to findings recently published in Nature. Most importantly, the Thailand case study provides probably the best real-world proof of concept that fisheries reserves can benefit not just oceans, but freshwater, too.

“These small, community-based reserves can be a really effective management strategy for sustaining their own resources and conserving fish,” says Aaron Koning, a postdoctoral researcher at the Global Water Center at the University of Reno, Nevada, and a National Geographic explorer. “This is some of the first science to show that this approach is really effective in freshwater, and suggests that we should maybe start applying this as a conservation tool.”

(Take a photographic journey into freshwater to meet the incredible creatures there.)

A much-needed break

Such tools are desperately needed. Freshwater animals are declining at rates more than double those of land and marine ones, yet they’re chronically overlooked. Their habitats in many rivers are affected by myriad threats: from dams and irrigation diversions, pollution, sand mining, and invasive species.

While freshwater reserves will not solve everything, in places where fish populations are under pressure, they can give species much-needed breathing room to rebuild their numbers, ultimately making them better able to weather other environmental assaults. Larger populations are less likely to go extinct than smaller ones, and are also more adaptable due to higher genetic diversity. Freshwater reserves provide “a tool that could buy us some time to start addressing much larger conservation strategies,” Koning says.

Southeast Asia, which has rivers and lakes that are some of the most heavily fished in the world, also has a long history of self-governed freshwater reserves, usually established as sacred pools around religious temples. The first Ngao River valley community reserve was established in 1992, and slowly, other villages—observing the success of their neighbors—replicated the project.

The rules are usually simple: no fishing of any kind in an agreed-upon area demarcated by flags or signs. Punishments for violators vary. In Na Doi, for example, fines start at 500 baht (about $17) per fish, regardless of the animal’s size, and increase for subsequent offenses. In another village, rule breakers must pay with 12 bottles of whiskey and a pig sacrifice to appease the spirits.

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Accidental networks

In 2012, Koning, then a doctoral student at the University of Wisconsin, Madison, began investigating the Ngao valley reserves to see how widespread and successful they truly were. Over the next eight years, he spent a total of 18 months living with communities across the region, where he documented around 50 different reserves. He selected 23 to study in depth, interviewing villagers and snorkeling the waters inside and outside the reserves to count and measure fish, along with study co-author Martin Perales.

Koning found, not surprisingly, that older and bigger reserves were more successful, because they offered more time and space—including more kinds of habitat—in which to rebuild fish populations and re-establish rare species. But even reserves established in the last couple years showed clear benefits from being spared intense fishing pressure. Reserves that were located closer to a village tended to have an advantage, Koning says, probably because villagers were better able to enforce the rules.

“These principles have been much more fully developed and demonstrated in marine reserves, but we think that’s what might be driving the success that we saw in our study, too,” Koning says.

While some of the reserves are “laughably small,” he says—just the size of a kiddie pool—they are all relatively close together, inadvertently providing a network of safe havens for fish species that travel up and down the river and its tributaries, in addition to those that stay put.

The magnitude of the overall benefits “is really surprising,” Koning says. He and his colleagues reported that, compared to non-protected stretches of the river, reserves enjoy more than twice the total number of fish and over 20 times the total weight of fish, with big fish found almost exclusively within protected areas.

“This is the first time we have had such a high-profile, quantitative study that’s directly measuring the benefits of freshwater protected areas,” says Erin Loury, a fisheries biologist at FISHBIO, a global fisheries and environmental consulting company, who was not involved in the research. “The fact that communities did this on their own with very little external support or funding is quite remarkable and is the best-case scenario you could hope for.”

Hard-to-see successes

In follow-up studies, Loury would like to see an in-depth analysis of the social factors that contributed to the communities’ accomplishments. She wonders, for example, if the Thai reserves benefited from the fact that villagers could literally see their successful efforts swimming around in the clear waters of the Ngao River. When freshwater bodies are turbid—which many are—the gains from fishing limits may be harder to convey.

Since the study came out, Koning has received reports about similar initiatives in Malaysia, India, and Namibia. Conservationists have also contacted him about replicating successful aspects of the Thai case study in various countries in South America and Southeast Asia. At the same time, he has begun researching the effects of eight large, government-mandated, no-take zones established in 2013 in Cambodia’s Tonlé Sap Lake, a hugely important fishery where reports indicate fewer and smaller fish are being caught.

By comparing different systems and approaches around the world, Koning and his colleagues hope to identify common factors for success that could be tailored to diverse rivers and lakes. “There’s a ton of mystery still in how and why these things work, but the first lesson is that they do work,” Koning says.

It’s a message that Nok Wa heartedly endorses as well. “If we didn’t have a reserve, our children wouldn’t be able to see fish, and we wouldn’t have fish to eat,” he says. “If a community starts a reserve, they will definitely get more fish.”