Standing at the edge of Keawanui fishpond on Moloka‘i, ‘Ua Ritte can see at a glance what’s working and what’s not. Hundreds of silver fish the size of popsicle sticks huddle in the sun-gilded shallows, nibbling algae. These are ‘ama‘ama, or mullet, an herbivorous reef fish once prized by Hawaiian royalty.

Their presence indicates that the eight- hundred-year-old coastal fishpond is functioning as designed. If all goes well the fingerlings will grow to forearm length, the ideal size for harvest. But floating in the water beyond them are gooey orange blobs: invasive upside-down jellyfish that threaten to throw the pond’s equilibrium off.

Three years ago Ritte watched as a few stray jellyfish ballooned into a suffocating mat that covered three-quarters of the pond’s surface and destroyed the habitat for ‘ama‘ama and other bottom-feeding fish. Ritte fabricated reinforced scoop nets and waded in after the stinging invaders. “We took out sixty thousand pounds one month—a ton a day—and it didn’t make a dent!”

He isn’t sure what caused the swarm. Upside-down jellyfish are attracted to the still waters of fishponds but don’t usually appear in such numbers. “Water temperature might be it,” he says. “The pond could be one degree warmer than the ocean.” Ritte shakes his head but he isn’t discouraged. The jellyfish plague is just the latest puzzle to solve at the fishpond.

Humans have always found ways to propagate their favorite fish: The Romans farmed eels and oysters, the Chinese fattened carp in ponds and people across Polynesia corralled reef fish into stone-walled traps. But nowhere else in the world were these fishponds as numerous and varied as in Hawai‘i. Known as loko i‘a, Hawaiian fishponds are among the great engineering feats of antiquity. Built six to eight hundred years ago, they allowed the people who lived here to maximize the productivity of marine and riparian eco-systems without exacting a heavy toll. “Fishponds were things that beautified the land,” wrote Hawaiian historian Samuel Kamakau. “A land with many fishponds was called momona [fat].”

Hawai‘i was definitely momona in days past; a statewide survey in 1990 identified 488 historic loko i‘a sites, ranging from tiny tidepools to enormous walled sea ponds like Keawanui. The largest loko i‘a belonged to influential ali‘i (chiefs); their construction required tens of thousands of laborers passing stones hand to hand, sometimes over great distances. Hawaiian aquaculture expert Graydon “Buddy” Keala estimates that prior to Western contact, loko i‘a produced a minimum of two million pounds of fish per year—“a significant amount considering the minimal input and maintenance effort.”

For generations these tremendous resources lay dormant, many of them buried and forgotten. Following the overthrow of the Hawaiian monarchy in the late 1800s, the systems that supported the loko i‘a fell apart. Like many traditional practices, Hawaiian aquaculture began disappearing in the early to mid-1900s. Multiple factors contributed to the decline: Development on land led to erosion, which filled ponds with silt. Invasive species such as jellyfish, mangrove and gorilla ogo (a non-native seaweed) compromised pond ecosystems. The convenience of grocery stores rendered labor-intensive fishponds less attractive. When tsunamis and storm surges broke down pond walls, there was little incentive to rebuild them.

By 1985 only seven fishponds were still functional. These were mainly leased by commercial farmers trying to raise whatever was most lucrative: catfish, trout or seaweed for sushi restaurants. The legacy of loko i‘a was all but lost. In the past thirty years, however, there’s been a resurgence in fishpond activity. Across the archipelago, people like Ritte are breathing life back into the old ponds, rebuilding their walls and restoring their balance. Each loko i‘a faces different challenges—upside-down jellyfish are a plague unique to Keawanui—but all grapple with the same essential questions: What role do traditional fishponds have in modern Hawai‘i? Can they feed the people again?

Seen from above, the remnants of Moloka‘i’s ancient fishponds look like necklaces strung along its cyan coast. Over sixty loko i‘a once sustained the island’s residents and satisfied the ali‘i living across the channel in Lahaina, Maui. ‘Ua Ritte’s father, the well-known Moloka‘i activist Walter Ritte, recognized the potential the neglected ponds had for feeding his community. In the early ’90s he spearheaded a restoration effort at Honoliwai, the island’s easternmost loko i‘a. But too many tourists liked to swim there. Plus, the pond was too small and its rocks too huge. “It took us all day to move one rock,” says ‘Ua. After a few more false starts, the Rittes settled at Keawanui, a fifty-acre fishpond belonging to Kamehameha Schools.

While the Rittes had plenty of ponds to choose from, they found few who knew how to work them. In ancient times each pond had a kia‘i loko, resident guardian, who knew its inner workings at every hour, season and tidal shift. The kia‘i loko protected the fishpond from poachers and supervised its maintenance, production and harvest. His wealth of knowledge—a blend of hard science and spirituality—stayed within the family and was passed down through generations. According to Keala, “The keeper was very powerful in his capacity as fishpond manager, and his decisions were highly respected and might even be held above those of the ali‘i in regard to pond management.”

Unfortunately, at least two generations had passed since the fishponds were in active use; nearly everyone who possessed practical or inherited knowledge of the loko i‘a was long gone. “We had to start from zero,” says ‘Ua. “Intensive fish farming—that was the only blueprint we had.” So father and son plunged in and began researching the mechanics of the loko i‘a from the inside out.

First they assessed the pond’s retaining wall: a slender ring of stacked rocks that had withstood the surf for eight centuries. What looked simple was in truth quite sophisticated. The pond’s original architects had angled the seaward side of the wall to deflect wave energy. They also fortified it with coralline algae, a seaweed that secretes a natural binding agent and cements rocks together. As the Rittes repaired the kuapā, or wall, they experienced firsthand the genius of their Hawaiian ancestors.

Traditional Hawaiian aquaculture capitalizes on natural cycles. Early Hawaiians understood that two of their preferred fish are catadromous: ‘Ama‘ama and awa (milkfish) spend their juvenile stage in the shallows, near sources of fresh water, and their adult stage in deeper, saltier currents. So enterprising fishermen built rock walls around the mouths of streams or springs, creating coastal ponds where the pua (fry) could thrive. They outfitted the walls with mākāhā, simple sluice gates that allowed fingerlings to enter but prevented larger predators from following. The pua gorged on the limu (seaweed) flourishing in the pond’s brackish water. Some swam back out to the sea to reproduce while others grew too big to fit through the mākāhā. Easy pickings.

The mākāhā was the innovation that distinguished Hawaiian fishponds from others around the world. By opening and closing the gate during tidal events, rain-storms or fish spawns, the kia‘i loko could control—to some degree—the water’s salinity, temperature and fish populations. Reliably, when ‘ama‘ama and awa reached peak maturity, they gathered at the gate during a flood tide.

In a December 1869 issue of the Hawaiian newspaper Ke Au Okoa, Kamakau described how, during high tides, fish migrated from the middle of the pond to the mākāhā: “The fish would scent the fresh sea and long for it. I have seen them become like wild things.” On these nights, Kamakau says, the kia‘i slept in a watch house beside the gate to guard the fish from being stolen or killed by pigs and dogs. “The keeper would dip his foot into the water at the makaha and if the sea pressed in like a stream and felt warm, then he knew that the sluice would be full of fish.… Where the fish had been raised like pet pigs, they would crowd to the makaha, where the keepers felt of them with their hands and took whatever they wanted.”

The promise of this delicious abundance spurred the Rittes on in their work. By 2004, with volunteer help, they had repaired Keawanui’s wall and installed a new mākāhā. Next they had to figure out how to jump-start the pond’s natural productivity. At least they had colleagues to consult: People on other islands had been restoring loko i‘a of their own.

Moloka‘i was known for its fish-ponds—and the fat, succulent mullet they produced—but O‘ahu had bigger ponds and more of them. The largest loko i‘a in all of Hawai‘i enclosed 523 acres within a five-thousand-foot-long retaining wall. Keahupua-o-Maunalua (“shrine of the baby mullet at Maunalua”) was filled in the 1960s to create the neighborhood of Hawai‘i Kai. Pearl Harbor’s fishponds suffered a similar fate: Just three out of twenty-two remain intact. Two of Kāne‘ohe bay’s twenty fishponds are still active.

In 1988, Mary Brooks leased He‘eia, an eighty-eight-acre fishpond on the shore of Kāne‘ohe bay. Mangroves choked the north end of the pond, and its wall had a gaping hole in the center, but Brooks was determined to coax it back into production. Fixing a busted seawall is no easy task, especially if you aren’t an ali‘i in command of ready hands. Brooks and a crew of university students devised a fix: They piled concrete traffic dividers in an arc around the hole. It worked well enough.

Brooks blended Western and traditional Hawaiian techniques to successfully raise ‘ama‘ama, moi (threadfin) and tilapia in the pond. In 2000 she taught the University of Hawai‘i’s first fishpond management class. The following year, some of her Hawaiian students were inspired to take the experiment a step further; they founded Paepae o He‘eia, a nonprofit devoted to returning the pond to its traditional glory.

“The place grabbed hold of me and didn’t let go,” says Keli‘i Kotubetey, one of Paepae’s founders and its current associate executive director. He also serves as the pond’s modern-day kia‘i loko and has lived on-site for the past three years. “It’s my job to watch,” he says. “Before, we used to find poachers’ lay-nets and crab pots. Now that we’ve opened up the pond, there’s nowhere to hide.” Opening the pond was Paepae’s first task. Every Saturday, the Paepae founders rounded up a battalion of volunteers to cut back the mangroves that had infiltrated the pond and weakened the seawall’s integrity.

In 2004, when Walter Ritte formed Hui Mālama Loko I‘a, a network of fishpond practitioners, Paepae hosted the group’s first gatherings. People came from across the state to learn about loko i‘a, support each other’s restoration efforts, teach one another skills and share resources. The group has since swelled to over one hundred practitioners representing thirty-eight fishponds. The progress at Keawanui and He‘eia have inspired similar projects at Ko‘ie‘ie in south Maui, Haleolono in Hilo and Wai‘ōpae on Lāna‘i, to name just a few.

Everyone is anxious to see fish multiplying in the ponds, but the learning curve has been steep and long. So far, the vision of ‘ama‘ama crowding the mākāhā has proved elusive. Just as the Rittes were starting to see recruitment of pua in Keawanui, a tsunami took down the wall. They started over, replacing the fallen rocks. Then came the upside-down jellyfish. Over at He‘eia an especially strong El Niño in 2010 caused the water temperature to spike, resulting in low dissolved oxygen. Most of the pond’s fish died.

Some of the obstacles today’s loko i‘a practitioners face are age-old: Storms blow out the mākāhā, or poachers pinch the fattest fish. Other problems are new, manifestations of the modern world: land-based pollutants and invasive species with which ancient Hawaiians didn’t have to contend. In 2015 the Oceanic Institute initiated a multiyear study at three ponds, delivering baby mullet to special pens within Keawanui, He‘eia and Haleolono. The fish failed to thrive. The pens may have been situated in the wrong places—too far from the fresh water. Every setback is a learning opportunity.

As a whole, challenges at the fishponds have been balanced by terrific successes. In 2014 Kotubetey and his colleagues decided it was time to mend He‘eia’s wall—to embark on not just a stopgap, but a real restoration. They launched a yearlong campaign called Panikapuka, or “close the hole.” They raised over $100,000, but more significantly they rousted the community, waking people up to the possibility of a functioning Hawaiian fishpond. The campaign’s final day was one for the ages: Nearly two thousand people lined up to pass rocks hand to hand—something that hadn’t happened for at least two centuries.

The workforce included local fishermen, students, researchers and chefs. Even Gov. David Ige pitched in. Before starting, the entire group intoned a Hawaiian oli (chant), describing the act of raising the wall, setting the foundation and securing its final stones. The sky, which had started out fickle and overcast, began to brighten as the crew got busy plugging the puka (hole) with stones. “It was amazing, super powerful,” says Kotubetey. “It was a restoration not just of the fishpond, but of fishpond practice.”

He‘eia’s wall is extraordinary; unlike most kuapā that span from point to point across a bay, this one completely encircles the pond. Measuring close to seven thousand feet, it’s the longest in Hawai‘i. It originally had six mākāhā, three facing He‘eia stream and three facing the ocean. During the process of mending the wall, Kotubetey and his crew noticed that water poured forcefully through the gap, attracting fish. Rather than seal up a passage the fish had grown used to, Paepae’s leaders decided to add a seventh sluice gate. “We are adaptive and resilient,” says Kotubetey. “Our ancestors didn’t thrive here for thousands of years by being inflexible.” Made of mangrove stumps and bamboo, the new mākāhā is so heavy it takes four people to open—guaranteeing that the pond’s management will always be a collective effort.

Another loko i‘a success story came from a perhaps unlikely corner: the Four Seasons Resort Hualalai. The hotel on the north Kona coast runs a surprisingly robust aquaculture program. Director of natural resources David Chai manages a team of five biologists who oversee the property’s anchialine ponds, oyster lake, shrimp and tilapia tanks and Waiakauhi, a two-and-a-half-acre traditional fishpond. Waiakauhi is an example of a loko pu‘uone, a fishpond naturally separated from the ocean by a sand berm. Previously, a sluice connected the two bodies of water. By the time Chai arrived in 1996, the channel and mākāhā were long gone. The pond itself was buried under thickets of kiawe (mesquite), man-grove and sodgrass. After he dredged sediment and cleared the weeds, a mix of native vegetation and plants the early Polynesians had brought to the Islands sprang up: ‘aki‘aki grass and hau and milo trees. “We didn’t plant anything,” he says. “The seed bank was waiting underneath.”

Chai made sure to leave islands within the pond for native shorebirds to safely nest away from cats and mongooses. He’s since witnessed sixty-five endangered ae‘o(Hawaiian stilt) chicks fledge—an impressive accomplishment considering the island’s total ae‘o population numbers three hundred birds. He stocked Waiakauhi with mullet but hasn’t been able to rebuild its mākāhā: Too many regulations prohibit shoreline construction. Meanwhile, hotel guests can eat tilapia, oysters and shrimp all grown in ponds on the property.

Kualoa Ranch is selling fish from its loko i‘a, too. The ranch owns Mōli‘i, a sprawling fishpond a few miles north of He‘eia. Ku‘uipo McCarty grew up next door to the 125-acre pond and watched its former lessee George Uyemura work the mākāhā and draw Samoan crabs and kākū (barracuda) from its green water. Now she does the same as pond manager for the ranch. Each month, she harvests around one hundred pounds of fish—kākū, pāpio, to‘au and ‘ō‘io (bonefish)—which the ranch sells to local restaurants such as Fresh Catch. Those fish are predators, not the coveted mullet and milkfish typically associated with fishponds, but McCarty has found a market for them.

The ranch’s big sellers are Pacific oysters. Ten years ago Kualoa began working with the state Department of Health to introduce the mollusks, which clean the water as they feed, into the pond. Over years of trial and error, McCarty increased the harvest from a few baskets to a quarter-million oysters per year. They’re now for sale at the Kualoa Ranch visitor center for $15 a dozen. The journey to obtaining approval to sell oysters was lengthy, but the path has now been paved—good news for other fishpond managers who hope to market their own.

Twice a month the team at He‘eia harvests crabs to sell to local restaurants and give to their supporters. Once a month during the summer, local residents can fish from the wall (for predator species only). Meanwhile, fishpond managers have learned that loko i‘a produce far more than fish. The ponds serve as conduits for community building, cultural education and scientific research. People come to the water’s edge to kilo (observe) as their ancestors once did. It’s nourishment of a deeper sort.

Students come to the loko i‘a to practice math and science in a living laboratory. They monitor the pond’s turbidity, salinity and dissolved oxygen levels—just as a traditional loko kia‘i might have, only with the benefit of modern tools. Each student leaves likely knowing more about loko i‘a than his or her parents. At Keawanui a class conducted a three-week study on the invasive jellyfish, researching methods of control. “Our goal was to raise fish,” says Ritte, “but you get way more out of this pond with educational programs.”

Over the past eighteen years, Hawaiian fishponds have offered tens of thousands of volunteers a crash course in indigenous aquaculture. Some of these volunteers get hooked and turn their fishpond habit into a career. A former He‘eia intern, Brenda Asuncion, now serves as a state fishpond coordinator. Maury Gutteling, also from He‘eia, now manages Haleolono in Hilo. Kotubetey hopes the poachers he’s occasionally caught will see how the pond is transforming and return to help. “Come give a bit of yourself before you take,” he says. “It’s about reciprocity.” HH