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Kualoa Ranch uses oysters to organically clean its fishpond and newspapers with banana and coconut leaves to grow taro with less weeding

Farmers and researchers are using oysters in a more than 800-year-old loko ia, or fishpond, on Kualoa Ranch, blending Hawaiian heritage and today’s innovation to overcome problems pre-contact Hawaiian farmers did not have to face. The problems include not having enough fish to eat pond algae and a lack of banana and coconut leaves to help grow taro better by keeping down weeds, they said.

In fact, according to Kuuipo Mccarty, fishpond caretaker and “oyster maiden” at the ranch, Kualoa Ranch has become home to Hawaii’s only loko ia that can sell the oysters used to clean the water in the pond as food.

“There are projects in Hawaii using native oysters to clean contaminated water. You shouldn’t eat those oysters.” The oysters Mccarty raises, however, are “delicious and sweet” because so many years have gone into cleaning the water of the ranch’s loko ia.

Mau and Mccarty standing side by side wearing long-sleeve green shirts with hats on in front of the pavillion where they take care of the oysters. There is a beautiful background of green palm trees and mountains.
Mau and Mccarty smiling in front of where the oysters are taken care of at Kualoa Ranch.


At some point, carnivorous fish were introduced to the loko ia, she said. Thus, so many herbivorous fish were being eaten there wasn’t enough fish to eat the algae that grows there. Soon, the loko ia had nearly three quarters of its surface covered in a thick mat of algae, preventing sunlight from reaching much of the pond. Because this was not a problem the ancient Hawaiians would have encountered, she said there was no age-old wisdom on how to combat it.

Mccarty credits former Kulaloa Ranch employee Bruce Anderson with the new addition to restore the loko ia to its former function. By adding oysters to the pond, the algae began to clear up.

“An adult oyster can filter-feed about 25 gallons of water a day, on average,” said Mccarty, holding the palm-sized shell of one in her hand. “They feed on the nutrients the algae would eat.”

Four oysters resting on a wood table.
Some of the oysters Mccarty cares for.


Dr. Anthony Mau works as the diverse agriculture manager and oversees food production at Kualoa Ranch, including the growth of taro. He received a doctorate from the University of Hawaii with a specialized background in aquaculture.

Mau said aquaculture often gets a “bad rap” because aquaculture projects in the past have polluted nearby waterways with excess fertilizers and nutrients. Oysters, however, actually improve water quality. While the water in Kualoa Ranch’s loko ia already passes a stringent 15-series quality test set by the FDA to allow the ranch to sell its oysters as food, the water at other locations around Hawaii is still in the process of being cleaned, said Mau.

He also came up with a way to preserve ancient Hawaiian tradition while making adjustments to suit available resources to grow taro. “It’s not just for show,” Mau said of their loi kalo, which are rectangular ponds with mud heaped into long “mo’o” or “lizard-style” mounds planted with a row of taro. According to Mau, growing the taro in this way maximizes yields. “It’s authentic, and it makes sense to be authentic. This is what’s meant to grow here. … When planting, you need to listen to what the climate is saying.”

Traditionally, Mau said after the taro were planted, banana and coconut leaves were placed around the stems to prevent weeds from sprouting and water from evaporating. Banana and coconut leaves were a plentiful resource in pre-contact Hawaii, but not so much today because coconuts and bananas no longer grow as plentifully. However, without them, the mo’o quickly become covered in grass, impeding the growth of the taro as they suck up nutrients.

Mau’s solution to the problem, he said, was inspired by a common practice in Japan where gardeners use old newspaper as mulch. By covering the mud with a thick layer of newspaper before adding the banana or coconut leaves, the same effect can be achieved with less leaves. Following this practice allows Kualoa’s farmers to stretch their supply of leaves further. Additionally, Mau said newspaper is plentiful and actually improves the quality of the soil by adding carbon back into it as it breaks down.

Taro plants in the brown water with beautiful green mountains and a blue sky in the background.
The taro plants at Kualoa Ranch.


“There used to be over 300 varieties of taro, but many of them have died out,” said Mau. “A lot of the loi were converted into rice paddies when the Chinese and Japanese immigrants came, but nowadays a lot of people are growing taro [in those places] again. … Taro, along with sweet potato and ulu [breadfruit], is at the forefront of Hawaiian agriculture.”

Kualoa Ranch’s popular Taste of Kualoa tour, which takes visitors through its agricultural sections and allows them to sample what is being grown and harvested, reopened in April.

Ahupuaa system
For thousands of years, native Hawaiians used a special agricultural system called ahupuaa, which covered everything from the mountains to the sea, to sustain a population similar in size to the one in Hawaii today. Although much of this old land has now been developed, Mau said, the agricultural techniques the native Hawaiians used to grow food still work best.

Amy Campbell, who lives in the town of Volcano on the Big Island, has a degree in sustainability and works for a large conservation group. She studied the ahupuaa systems on Maui and said they are incredible.

“When I first started studying systems, I was shocked at how intricate it was,” she said. “They used the waterflow that naturally occurred to irrigate a number of fields.” She said the taro was typically kept at the top, with other crops, like ulu, at the bottom. According to her, people are typically shocked when they learn how much food the ahupuaa system produces. She said pre-contact Hawaiians and those who maintain the practices today are “incredible botanists.”

The loko ia, or fishpond, is traditionally built where the ahupuaa meets the coastal plain, Campbell explained. “If I was going to scientifically go in and design the ideal fishpond, I don’t think I could match what they did,” she said. “They were ingeniously designed.” Fish enter the loko ia while small and grow large within its walls by eating algae. Because of this, she said Hawaiians ate almost exclusively herbivorous fish that were low on the food chain.

The fishpond at Kualoa Ranch. A palm tree covers the right of the frame along with some Hawaii mountains.
The loko ia at Kualoa Ranch.


To harvest the fish out of the loko ia, she said they used a plant called ʻākia to stun them. It’s just poisonous enough to the fish to temporarily immobilize them, but completely harmless to humans. After the harvest, the fish that weren’t eaten were released back into the ocean, where the ʻākia wore off and the fish “came magically back to life. That plant was endemic and only found in Hawaii, so they learned about that and used it,” said Campbell.

While using a loko ia to collect fish is no longer a common practice, restoring them is a hot topic among preservationists. In Haleiwa, the Malama Loko Ea Foundation works tirelessly to restore the Loko Ea fishpond. On its website, it describes Loko Ea as “a sacred space for the community of pae ʻāina o Hawaiʻi” because it’s a place to practice culture, share heritage and celebrate community.

The website says the group has two sand-dune ponds in Waialua connected to the ocean through a stream or ditch. “Connected physically through the streams and freshwater springs, they are also spiritually connected, as both are the home to Laniwahine, the moʻowahine female water guardian of the two fishponds. Together, they make up the third largest existing wetland on the island of Oahu.”

The Malama Loko Ea Foundation runs community workdays every Saturday between 9 and 11 a.m. Under current COVID-19 protocols, participants must pre-register groups between three and 10 people on its website.

Other aspects of the ahupuaa system, such as the loi kalo or taro fields, are also actively preserved around Oahu and on the BYU–Hawaii campus. One such example is a community nonprofit in Hakipuu Valley, Hoʻāla ʻᾹina Kūpono. The Hakipuu loi kalo has been tended to using traditional techniques for hundreds of years without interruption, says the Hoʻāla ʻᾹina Kūpono website. According to the Trust for Public Land, more than $1 million was raised in 2016 in order to preserve the loi kalo. Today, the nonprofit is still growing taro and the space is an outdoor classroom for students of restorative agriculture.

BYUH also participates in restorative agriculture by growing various native plants using traditional techniques in the Hawaiian studies garden. A similar arrangement can be observed on a visit to Waimea Valley.

However, restoration isn’t the only way to keep native Hawaiian agriculture alive. Other places where modern farming techniques are combined with tradition, allowing farmers to grow both native and introduced plants, include Kahuku Farms and the farms at the Polynesian Cultural Center.