Restoring Indigenous aquaculture heals both ecosystems and communities in Hawai‘i

For generations, native Hawaiians have understood that their aquaculture systems, fishponds known as loko i‘a, serve as nurseries that seed fish populations in surrounding waters. For the first time, a team of scientists from the Hawaiʻi Institute of Marine Biology (HIMB) have modeled this feat of Indigenous science in a study.

“We are using science to translate ‘ike kupuna, or Indigenous knowledge, into policy,” said study co-author Kawika Winter, an ecologist at HIMB and He‘eia National Estuarine Research Reserve (NERR). “The value of this paper is that it’s one of the first, if not the first, to really show that there are ways to do aquaculture in ways that benefit the system around it.”

In partnership with He‘eia NERR and Paepae o He‘eia, a nonprofit organization dedicated to stewarding the He‘eia loko i‘a, an ancient Hawaiian fishpond enclosing 36 hectares (88 acres) of brackish water, the team simulated different restoration scenarios in ‘Kāne‘ohe Bay on O‘ahu Island based on a simplified food web. The study found that restoring more of the bay into fully functional loko iʻa would grow fish populations not just within the ponds, but across the bay.

A unique design

The Indigenous aquaculture systems found in Hawaiʻi have a unique design that supports the ecosystem in a way that commercial aquaculture doesn’t. There are six types of loko i‘a in Hawai‘i, each designed to complement existing features in the landscape.

The type of fishpond modeled in the study is called a loko kuapā, or walled fishpond, where a boundary rock wall encloses part of the ocean at the mouth of a nutrient-rich stream. By trapping nutrient-rich stream water, the enclosed space incubates phytoplankton, triggering algal blooms that feed herbivorous fish, thereby boosting herbivorous fish populations to levels much higher than in unmanaged estuaries.

Sluice gates, or mākāhā, are built into the wall to circulate water and allow young fish to move in and out of the pond, while separating larger fish from predators. The young fish leaving the pond often move into the bay’s larger ecosystem, where they become a food source for reef fish and fishers alike.

“In this way, the design manipulates preexisting natural conditions so that they’re extra productive,” said lead author Anne Innes-Gold, a marine biology Ph.D. candidate at HIMB. “Loko i’a are really built to work with the ecosystem, whereas not all forms of aquaculture are made to do that.”

Unlike commercial aquaculture, these traditional fishponds thrive without feed input and need little management once established.

“Aquaculture has a really bad reputation for basically destroying areas around it, but those are commercial approaches to aquaculture that aren’t holistic in their thinking or values-based like Indigenous management,” Winter said. “Rather than ensuring the health of the system, commercial aquaculture is concerned with maximizing profits.”

Winter noted that a key difference between commercial and Indigenous aquaculture is the type of fish produced. Indigenous aquaculture produces herbivorous fish, whereas most commercial aquaculture produces lucrative carnivores such as tuna and salmon. These fish require the input of feed like fishmeal and fish oil, whose production uses 20% of global wild fish catch. At times, this fishmeal catch is linked to unsustainable fishing practices, like trawling, or undermining the food security of coastal communities.

“From a capitalist model it makes sense to grow predators, but from an environmental stewardship model that’s the dumbest idea ever,” Winter said. “Because you could either feed your people 100 pounds of baitfish, or you can feed your people with a 10-pound ahi [tuna].”

A common concern among environmentalists of commercial aquaculture systems is the release of waste into surrounding waters. This waste can contain antibiotics, pesticides and fish feces that render waters unsafe for human drinking, recreational use and other wildlife. Many loko i‘a restoration sites, on the other hand, have been found to improve water quality and increase populations of native species. This is because restoration entails removing invasive mangroves and planting native vegetation. In this way, loko i‘a restore rather than destroy natural ecosystems like their commercial counterparts.

Winter attributed the success of the loko i’a design to Indigenous thought processes: “Indigenous thinking is operating within the opportunities and constraints of this system and figuring out a way to make things abundant within that context, sometimes even increasing abundance beyond natural levels.

“That’s the way the kupuna [ancestors] did it, and we’re reviving that,” he added.

This study adds to a body of work demonstrating the potential for Indigenous aquaculture to increase locally available seafood in Hawai‘i. Today, Hawaiʻi imports almost 90% of its food, including 63% of its seafood. But historically, working fishponds contributed almost 2 million pounds (907 million metric tons) of fish annually as part of an agroecological system that supported almost 1 million people, close to its current level of 1.4 million.

Imports increased as development, land-use change and invasive mangroves destroyed most fishponds. Only in the 1970s did a revival movement begin. Now, of the nearly 500 original ponds, 20 have received restoration permits throughout the state of Hawai‘i, and restoration is underway for many others.

But threats still remain for Hawai‘i’s fishponds, as climate change impacts freshwater reliability in the streams feeding ponds and reef health impacts the broader watershed. “We’re on the doorstep of completing restoration,” said study co-author Keli‘i Kotubetey, from Paepae o He‘eia. “But we have come to realize that it’s not just about the physical infrastructure of the pond itself; it’s about the health of the whole system.”

Restoring ecosystems and relationships

Since co-founding Paepae o He‘eia in 2001, study co-author Hi‘ilei Kawelo, a sixth-generation Hawaiian from ‘Kāne‘ohe Bay, has witnessed thousands of volunteers transform the He‘eia loko i‘a.

“When we started, the fishpond was completely enclosed by invasive mangroves. You couldn’t even see the horizon or the fishpond wall from the shore,” Kawelo said. “But if you come to the fishpond today, you can see the fully restored wall, and there are only a few hundred feet of mangroves left.”

Now, as the nonprofit’s executive director, Kawelo is working to completely restore the pond while providing intellectual, physical and spiritual sustenance for the He‘eia community. This blend of ecosystem restoration, education and cultural practice is also known as biocultural restoration.

Biocultural restoration is a conservation approach aimed at revitalizing Indigenous stewardship by “restoring not only ecosystems, but also human and cultural relationships to place,” according to the State University of New York College of Environmental Science and Forestry. In this way, it says, “cultures are strengthened alongside the lands with which they are inextricably linked.”

With the ongoing restoration, Paepae o He‘eia has seen both the aquatic environment and participants’ well-being improve with increased access to traditional foods, strengthening their relationship to place, and fortifying their family and community relationships. “For me and for a lot of our employees, this is one of our outlets, if not our primary outlet for exercising aloha ‘ainā [love of the land],” Kawelo said.

“‘Ainā is so important, because it is a term for a system that has the nature and its people in an inseparable reciprocal relationship,” Winter said. “The concept is core to this work because it’s about getting back into a way of thinking where there is no separation between the lands, the waters and us.”

While the overarching goal of Paepae o He‘eia and other fishponds is to revitalize Hawai‘i’s extensive Indigenous aquaculture system, Kotubetey said he knows the work may take generations.

“It’s taken a long time for our fishponds to be degraded,” he said. “Restoration is a process that will require assistance and regular support at the community and governmental level. Because that’s how they worked in the past.”

Winter said he believes this study is another step toward communicating Indigenous knowledge to support governmental decision-making. Together with similar initiatives across the archipelago, these communities are weaving Indigenous knowledge together with Western ways of knowing to heal both ecosystems and communities.

Related podcast episode:

Banner image: He‘eia fishpond. Unlike commercial aquaculture, these traditional fishponds thrive without feed input and need little management once established. Image by Kelii Kotubetey.

Last of the reef netters: An Indigenous, sustainable salmon fishery

Citations:

Innes‐Gold, A. A., Madin, E. M., Stokes, K., Ching, C., Kawelo, H. I., Kotubetey, K. I., … McManus, L. C. (2024). Restoration of an Indigenous aquaculture system can increase reef fish density and fisheries harvest in Hawai‘i. Ecosphere, 15(3), e4797. doi:10.1002/ecs2.4797

Cashion, T., Le Manach, F., Zeller, D., & Pauly, D. (2017). Most fish destined for fishmeal production are food‐grade fish. Fish and Fisheries, 18(5), 837-844. doi:10.1111/faf.12209

Gallardi, D. (2014). Effects of bivalve aquaculture on the environment and their possible mitigation: A review. Fisheries and Aquaculture Journal, 5(3). doi:10.4172/ 2150-3508.1000106

Loke, M. K., & Leung, P. (2013). Hawai‘i’s food consumption and supply sources: Benchmark estimates and measurement issues. Agricultural and Food Economics, 1(1). doi:10.1186/2193-7532-1-10

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