The Hawaiians reviving their islands’ ancient aquaculture practices

Erica Gies

In an ocean state that now imports half of its seafood, a determined group of activists is restoring the age-old aquaculture practices of Native Hawaiians.

Erica Gies

This story originally appeared in bioGraphic, an online magazine about nature and sustainability powered by the California Academy of Sciences.

The little fish were just nine weeks old, but they had already gone for a plane ride. 

The striped mullet, called ‘ama‘ama in Hawaiian, had boarded a plane in O‘ahu and flown toward their past-inspired future: an ancient fishpond on the island of Moloka‘i, the center stone in the necklace of volcanoes that make up Hawai‘i. From the airport, they traveled in trucks to the Keawanui fishpond, a 500-year-old aquatic semicircle fenced off from the ocean by a basalt and coral wall. 

Activists hope to recreate a sustainable fishery by restoring and stocking fishponds like Keawanui along Moloka‘i’s southeast shore · Mickey Pauole

When the trucks pulled up to the 55-acre pond, Walter Ritte, a 70-something, whisper-quiet firebrand, climbed out, along with a group of fishpond restoration activists. They unloaded 10 insulated boxes containing bags of squirming fingerlings, or pua — young fish roughly the size of a human finger — and walked through a tunnel cut into the mangroves along the top of the wall, a parade of children and dogs trotting in their wake. Two men hopped into the pond, water rising to mid-thigh. They placed the bags in the water to acclimate the pua, monitored them for a time, then released the fish. The 3,500 or so fingerlings huddled together in the shallows, their gray bodies blending against the light brown muck of the bottom. Then they changed course, rolling in a sparkling silver wave. 

This moment was nearly 30 years in the making for Ritte — rhymes with “pretty” — a Hawaiian sovereignty activist who has been a key figure in Native Hawaiians’ efforts to regain access to the hundreds of vast fishponds crafted centuries earlier by their ancestors.

Starting around 1200 AD, ancient Hawaiians created a system unique in the world: hybrid, cultivated-wild aquaculture using ponds to trap, raise, and harvest ocean fish.

In 1830, the Hawaiian Islands had more than 450 fishponds, and Moloka‘i — known as ‘āina momona, or bountiful land — was the epicenter. Today, 60 half-loops of rock wall are still visible along its southern shore. The fishponds helped to feed as many as 1 million people in the days before European colonization, not far from the 1.4 million who live here now. Today, however, Hawai‘i imports more than 85% of its food, including 50% of its seafood. 

The yellowfin goatfish is one of ten goatfishes native to Hawai‘i, where they have long been a source of food · Yuko Stender

If Ritte and his comrades succeed in restoring them, Hawaiian fishponds could alter that balance. Industrial fish farms pollute waterways with thick plumes of waste, foster massive overuse of antibiotics, and incubate diseases that can spread to remaining wild fish stocks. But fishpond activists and scientists working with them to restore these systems believe there is a more sustainable model, inspired by the wisdom of the ancient Hawaiians. Their practices enforced limits on take to ensure that sufficient numbers of fish spawned and resupplied stocks, and used upland plantings to control water quality and nutrient flow into the ponds. “Nobody developed the integration of uplands and seawater — mariculture — like the Hawaiians,” says Barry Costa Pierce, a professor of marine sciences at the University of New England. 

“The ancients,” adds Ritte, “were fish-rearing geniuses.” 

After more than 40 years of campaigning for Hawaiian sovereignty, Walter Ritte, affectionately known as “Uncle Walter,” still finds a lot to smile about · Mickey Pauole

Ringing the dinner bell

Thanks to oral tradition, Native Hawaiians have some understanding of how their ancestors operated the fishponds. The ancients understood that herbivorous young fish are attracted to protected estuaries, where predators are fewer and freshwater from streams and springs mixes with saltwater to create a buffer of phytoplankton and algae. Hawaiians inserted themselves into this native ecosystem, extending estuary habitat by building walls to section off the shoreline in places where springs emerged.

Across small openings in the rock walls, they installed slatted gates that retained growing fish while allowing the outgoing tide to suck nutrient-rich water out into the ocean, inviting more young fish to enter. “It’s kind of like ringing the dinner bell,” says Brian Glazer, a professor of oceanography at the University of Hawai‘i at Mānoa. Upland of the ponds, the Hawaiians grew taro, their staple starch. These fields captured excess sediment and channeled important nutrients into the ponds, stimulating the growth of algae that served as prime fish food. 

Nonprofit Hui o Kuapā advocates Native Hawaiian rights and issues and organizes hands-on experience for people in the fishponds, or “loko i‘a” · Mickey Pauole

The living was easy in the ponds, and the herbivorous species attracted to them, such as striped mullet, milkfish, Pacific threadfin, and surgeonfish, would linger there. Fishpond caretakers deterred any predatory fish or people that entered their domain. A pond is like a pasture, says Ritte. “You don’t raise lions in a pasture. You raise cows.” When the fish were old enough to spawn, they would gather at the gates with each rising tide, ready to return to the ocean. The caretakers would then harvest some of them by net or by hand. 

Fishponds were fundamental to Hawaiian nutrition and culture. But that culture broke down by degrees during colonization and the US overthrow of the Kingdom of Hawai‘i in 1893.

The ponds fell into disrepair in the years that followed, devastated by erosion from unsustainable farming and ranching practices. As tourism and air travel boomed in the latter half of the twentieth century, the fishponds were filled to build ocean-front housing, or dredged out to create marinas. By the 1980s, the ponds were abandoned artifacts, grown over with invasive mangroves, partially filled with mud, their walls broken open by the sea.

Children learn the ways of the ancient Hawaiians at Hui o Kuapā’s learning center at the edge of the Keawanui fishpond · Mickey Pauole

Yet today, fishponds are on the brink of a renaissance — if revivalists can overcome a few big challenges. In 1989, Ritte co-founded Hui o Kuapā, a local fishpond restoration nonprofit, one of several now throughout the islands. These organizations work with local schools to educate students about Native Hawaiian culture and with scientists to study fishpond operations in hopes of recovering ancient knowledge. For Hawaiians such as Ritte, restoring fishponds means not just growing food but reconnecting with their culture.

But what worked in the past may need tweaking today, given intervening damage to the environment, including pollution, overfishing, invasive mangroves and jellyfish, and warming oceans that damage reefs. 

The river doesn’t flow straight

The island of Moloka‘i is one of the places where people are working to recover lost knowledge and searching for solutions to these new problems. Perhaps best known to outsiders for its historical leper colony at Kalaupapa, Moloka‘i receives less than one percent of Hawai‘i’s tourists. More than half its population of 8,000 are Native Hawaiians who want to preserve the “real Hawai‘i” here. To a large degree they have: there are two tiny towns, no chain stores or restaurants, no stoplights. In fact, “no” is a word you see often on Moloka‘i, on hand-painted signs along the main road: “no cruise ships,” “no short-term rental housing.” What people here do support is local food independence and native rights, the latter often marked by the Kanaka Maoli — a red, yellow, and green striped flag with crossed canoe paddles framing the Hawaiian royal standard — rippling on the trade winds in front of many houses. And any talk of these two intertwined movements soon evokes the name Walter Ritte. 

Despite the hurdles, including many stints in jail, Walter Ritte remains committed to the goal of Native Hawaiian sovereignty · Mickey Pauole

I met Ritte one day last November at Paddlers, an open-air bar and restaurant that is a center of social life in Kaunakakai, Moloka‘i’s largest town. Ritte is physically slight but well-muscled, with a full gray beard and dark head of hair, and so soft-spoken that I had to lean in to hear his deep, raspy voice, inflected with a Hawaiian lilt.

Ritte is a living legend in Hawai‘i’s native rights movement, known across Moloka‘i and beyond as “Uncle Walter.” He radiates an iron core of intensity and conviction that initially intimidates — until he flashes a sudden, crinkly smile so genuine that it brings the sun.

He wears a t-shirt that says “aloha ‘āina” — love and respect that which feeds you: the land, rivers, and ocean.

For 40 years, Ritte has been in the thick of the grassroots campaign for Native Hawaiian independence. Ritte first became involved in the movement in the 1970s, after he visited the US Navy bombing range on the tiny island of Kaho‘olawe. “I saw somebody killing an entire island,” he says. In 1976, he and other activists occupied Kaho‘olawe, hiding out on the island for 35 days. “We are a part of the land,” he says. “What you do to the land, you do to us; what you do to the land, you do to future generations.” The activists then filed a federal lawsuit against the Navy, touching off years of protests that ultimately succeeded in stopping the bombing and protecting the island for Native Hawaiian cultural, spiritual, and subsistence practices.

In the late 1970s, Walter Ritte and his family made their home in Moloka‘i’s Pelakulu Valley, living off the land as their ancestors had · Mickey Pauole

Toward the end of the 1970s, Ritte moved his family to Moloka‘i’s Pelakulu Valley, to try to live off the land as his ancestors had. Much of the area that Hawaiians had once used for hunting and fishing, however, was now owned by corporations and therefore off limits. But “the deer didn’t read any of the ‘no trespassing’ signs,” Ritte says, and he fought for the right to hunt. In 1978, Ritte and fellow activists won an amendment to the state constitution that acknowledged Native Hawaiians’ rights to access forests and shorelines for subsistence and religious purposes.

In 1989, the Hawaiian sovereignty movement turned its attention to using those newfound coastal access rights to reclaim and restore the fishponds. Ritte and his fishpond group, Hui o Kuapā, began cleaning up and restoring ponds on Moloka‘i. But it wasn’t moving volcanic rocks into place that presented the biggest challenge. It was bureaucracy. “We went to fix the walls,” says Ritte, “and we ran into the government.” 

Sources of fresh water such as springs and streams are integral to the Hawaiian fishpond system, providing nutrients that young ocean fish seek out as they develop · Mickey Pauole

It was death by a thousand documents: Army Corps of Engineers permits for altering “wetlands” — abandoned taro gardens — and “navigable” water in the ponds; water quality permits from the US Environmental Protection Agency and Hawai‘i Department of Health. The state Department of Land and Natural Resources, which had labeled the fishponds historical sites, required that Ritte’s group hire archeologists and soil corers to document and date the ancient walls. “They were trying to protect historic sites. We were trying to use historic sites,” says Ritte. “In their eyes, the Hawaiians are supposed to be dead and gone. So we’re all historic.”

It was taking up to 10 years and hundreds of thousands of dollars to win permission to restore and use a fishpond, says local attorney Kehau Watson. Then in 2012, her legal firm Honua (Earth) Consulting stepped in to streamline the federal and state permitting processes, condensing 17 authorizations from 12 agencies into a single five-page, 30-day process. After years of delay, 17 new fishpond projects moved forward across six islands. 

It has been a slow, meandering path, says Ritte, but one that he hopes will ultimately lead toward reclaiming Hawaiian rights and culture. “The river doesn’t flow straight. Only the Army Corps of Engineers believes that rivers flow straight,” he says, laughing. Protecting their land and values takes constant energy and effort, he says — and a certain mindset. “I make use of anything and turn it into a positive.”

Reconstruction of the rock walls that encircle fishponds is a hands-on, labor-intensive process for the Native Hawaiians seeking to reconnect with ancient traditions · Mickey Pauole

Modern challenges to ancient practices

With the fishpond bureaucracy tamed, Ritte’s group and other fishpond organizations are now learning how to operate these complex systems, partnering with scientists to study various farming techniques. In addition to the pua stocked at Keawanui Fishpond on Moloka‘i, fingerlings have been delivered to two other ponds, one on the big island of Hawai‘i, the other on O‘ahu. 

The Heʻeia fishpond, on the windward side of O‘ahu, is one of the oldest and largest in the islands, built about 800 years ago and enclosing more than 88 acres of water. Its relative proximity to Honolulu’s universities and nonprofits allows easy access for research. In recent years, Glazer, from the University of Hawai‘i at Mānoa, and his team have installed low-cost wireless sensors that measure weather patterns, tides, water temperature, light, dissolved oxygen, and acidity, to help them understand the range of conditions in which a fishpond remains healthy. 

In the early 1800s, more than 450 fishponds were dotted around the coastlines of the Hawaiian Islands · Mickey Pauole

Those conditions have not always been easy to establish or maintain. Earlier pua deliveries to Keawanui, He‘eia, and other ponds taught scientists and fishponders hard lessons about acclimating hatchery fish to pond life. Fingerlings younger than nine weeks proved too delicate to make the transition, and most died. Nursery pens were too big to manage or not close enough to freshwater to sustain the pua. Fishponders also used net pens before the rock walls were fully restored, and many of the baby fish escaped. Now the rebuilding is more complete, and any remaining net walls use multiple layers to keep the young fish contained. 

Despite the progress, says Glazer, modern fishponders face many challenges that did not exist centuries ago. The biggest issue is development, he says. Pavements and buildings funnel polluted runoff into the water, along with sewage and fertilizer. The fishponds were once part of an interactive system with the uplands, or ahupua‘a — the watershed and everything in it, including people. A fishpond without its upstream water management and taro fields is an incomplete system. “Fishponds are a great reflection of what’s happening above and below,” says Keli‘i Kotubetey, Assistant Executive Director of the nonprofit Paepae o Heʻeia, which manages restoration of He‘eia Fishpond. “Your fishpond is only as healthy as your ahupua‘a.”

Each fishpond is a unique system that requires nearly constant attention from its caretakers · Mickey Pauole

To restore this part of the system, a nonprofit called Kākoʻo ʻŌiwi began in 2010 to weed invasive species out of wetlands above He‘eia Fishpond and replant taro to stabilize runoff and improve nutrient flow. In 2017, He‘eia Fishpond was named part of a National Estuarine Research Reserve, supporting the restoration of the entire He‘eia watershed and funding studies of the effects of taro patches and fishponds on nutrients, sediment, flood protection, and local species.

Warming and acidifying oceans may also play out in unpredictable ways. Hawai‘i’s near-constant trade winds typically keep the ponds agitated enough for sufficient oxygen supply, but sometimes in summer, when winds slacken and temperatures rise, aquatic life is threatened.

A 12-year study of He‘eia Fishpond correlated two periods of fish die-offs with these weather events. As climate change intensifies, these extremes could happen more often.
Attracted as juveniles by the nutrient-rich waters of the Hawaiian fishponds, species including the goldring surgeonfish soon grow too large to leave · Keoki Stender

No YouTube videos

It is hard to find the required level of attention in industrial aquaculture operations. Each pond is a unique system, says Kotubetey. You cannot rubber-stamp production. A critical aspect of Hawaiian fishpond management is kilo, the practice of paying close attention to nuances of the environment. “There’s no manual, no how-to book, no YouTube video,” says Kotubetey. “We just gotta do it. We are trying to increase our observational skills, and watch, learn, and respond to the environment.” 

Ritte connected with kilo when living largely by subsistence in the Pelakulu Valley, a period he remembers as the best time of his life. “If you’re going to work every day on the freeway, you don’t have a clue what’s happening outside your rolled-up window of your air-conditioned car.” By contrast, in the valley, “I knew all the cloud movements, I knew the temperatures, I knew the ocean — all of those things became part of me. I could tell when it was going to rain and for how long. Nature talks to you. But nobody is listening.” 

Together with his wife Loretta, Walter Ritte has dedicated his life to the Hawaiian sovereignty movement and the preservation of natural resources · Mickey Pauole

Listening to nature will be crucial to success as fishponders envision it, as will keeping it community-based. The goal is not to create an intensive, profit-driven system but, rather, to feed people. “We’re trying to revive the relationship-based economy,” says Kotubetey, “an economy of shared values, aloha [love] for each other, aloha for this land.”

It is an approach that is compatible with international best practices, as defined by the FAO—the Food and Agriculture Organization — which issued a report a decade ago calling for traditional ecological practices and principles in aquaculture design, engineering, and management. “There are examples all over the world of industrial systems that are changing,” says Pierce, who served on the FAO advisory team. In Vietnam, for instance, coastal communities are beginning to grow shrimp among mangrove roots rather than tearing out the trees to build shrimp farms. Because mangroves provide natural habitat for the shrimp, the shrimp can forage in the wild, eliminating the need for additional feed or antibiotics.

Like a living, breathing jewel attached to the shore, the Kupeke fishpond promises a sustainable source of fish · Mickey Pauole

So, too, can Hawai‘i’s fishponds offer lessons for local aquaculture around the Pacific basin. “Part of our grand vision is to get it right in Hawai‘i first and then allow the Hawaiian fishpond restoration story to serve as a model,” says Glazer. People from New Zealand, Bangladesh, and Thailand have already visited He‘eia Fishpond to gain an understanding of how to restore their coastal food resources. “We’re connecting with more indigenous networks as time goes on,” says Kotubetey. 

But most important, for fishpond activists, are the connections they have made through this work to an ancient culture stripped from Native Hawaiians over the past two centuries.

The day I leave Moloka‘i, I take a final swim near the island’s east end, floating over a reef smothered in sediment and algae. But as I step out and grab a towel, my view opens onto the shore’s next half-moon, which holds a fishpond. An older man clad in a malo, the traditional Hawaiian loincloth, is moving slowly through the water with a bucket, working methodically, his bare back bent into a golden brown question mark. It is a vision from another century — and now, from this one as well. 

Traditional arts, sciences, and cultural practices are being rediscovered through the “Hawaiian Renaissance” · Mickey Pauole

In the broader narrative of reclaiming Hawaiian rights and culture, “maybe this fishpond story is just a little tip of the iceberg,” says Ritte. “That’s why, at my old age, I’m still excited.”


Erica Gies

Science journalist

Erica Gies covers water, energy, critters, and more on the science and environment beat. Her work has appeared in The New York Times, Scientific American, Nature, The Economist, and others.

Walter Ritte

Hawaiian sovereignty activist

Walter has been a pillar of social activism in Hawaii for over 40 years, fighting for decades to protect Native Hawaiian rights. He has also dedicated much of his time and attention to issues surrounding food sovereignty and environmental health. Throughout his activism, Walter is best known as the island of Molokai’s most ferocious watchdog.


Online nature & sustainability magazine

bioGraphic is an online magazine about nature and sustainability powered by the California Academy of Sciences.

Hui o Kuapā

Hawaiian fishpond restoration

Education is the “kua” or backbone of the Hui o Kuapā mission. Hui o Kuapā, founded in 1989, educates the local and global community about Native Hawaiian resource management and innovations through hands-on experience in the fishponds or “loko iʻa” as well as through advocacy of native rights and issues. The organization has been instrumental in raising awareness about the need to care for our planet and food security in rural communities. It proudly continues to carry out that mission today.

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