Farming on a Loop

by Jake Buehler

In Hawaiʻi and the Pacific, physical space for agriculture is substantially more limited than on continental landmasses. This has made farming practices that combine efficiency with a low impact on land and water use especially useful for producing food in the Pacific region. Now, one food production system is increasingly recognized here, and across the world, for its capacity to reduce waste and cost while still producing high yields: aquaponics.

Aquaponics is farming on a loop. Fundamentally, the process is a merger of aquaculture—where fish or shellfish are raised in tanks or ponds—and hydroponics, where plants are grown in water. Nitrogen-rich waste from the animals fertilize the crops, and in many closed systems, the water is moved in a cycle, nurturing the growth of animal and plant alike.

The method is relatively ancient, with early examples in East Asia and Mesoamerican civilizations dating back several centuries at least. Some early forms of aquaponics were raft systems, where floating vegetation grew directly atop a nutritive water body containing fish raised in culture. This method is still used today, but thanks to human ingenuity and technology, modern aquaponics has gone through a variety of customizable iterations.

The basic components are all shared between the variations: water, light for the plants, feed for the fish, bacteria to convert fish waste into chemicals that can be used by the plants, and an electric pump to move water through the system and keep the water well-oxygenated.

The payoff—often in the form of leafy greens like spinach or kohlrabi, and fish such as tilapia or catfish—is impressive. The process generally produces higher yields of both fish and crops for less water and feed than standalone farming and aquaculture. In catfish-pumpkin systems, for instance, aquaponics increases fish production efficiency by as much as 75 percent over other aquaculture methods, and increases pumpkin yields five-fold over growing the crop in irrigated soil.

The scalability of aquaponics, from commercial-scale farms to units that can fit easily in a backyard at relatively low operating cost, makes the approach particularly attractive in Hawai‘i, where food insecurity is an ongoing issue. Aquaponics is increasingly gaining attention for its potential role in being a sustainable, economically feasible method of making healthy foods available at multiple scales, and to increase crop and aquaculture efficiency overall. Cooperative efforts between federal and local governments, educational institutions, and nonprofit organizations are now encouraging the training and adoption of aquaponic techniques in Hawaiʻi and Pacific communities.

Planting the seeds, Teaching the fundamentals
GoFish Hawaiʻi is an aquaponics workshop series, run as a collaboration between the University of Hawaiʻi College of Tropical Agriculture and Human Resources (CTAHR) and the University of Hawaiʻi Sea Grant College Program (Hawaiʻi Sea Grant). The program operates out of CTAHR’s Waimānalo Research Station, providing training on aquaponics principles.

Dr. Kai Fox, one of the coordinators for GoFish and a Hawaiʻi Sea Grant extension specialist, says that there are roughly 35 students attending the workshop series at a time, and he sees a growing demand for training.

“A lot of the interest is not in really trying to reinvent your farm, but supplementing it with a new source of nutrient water to play with,” says Fox, adding that a key part of the workshop’s approach is “exposing [students] to the technology and letting the participants run with it.”

A few of the students have stayed on beyond the completion of the workshop series to conduct a practicum, notes Fox. The project is a “decoupled” aquaponics system where tilapia culture water is regularly used to irrigate a quarter-acre mixed avocado and citrus orchard. The system helps reclaim nutrients from the fish feed pellets.

Some high schools are also delving into aquaponics training. At Waiʻanae High School, on the leeward side of Oʻahu, aquaponics principles are taught as part of a broader aquaculture program at the Marine Science Learning Center, which has been active since the early 1990s. There, students get hands-on learning experience with aquaculture, providing the illustrative backdrop to develop an understanding of sustainability and ecological concepts. Students can design aquaponic-style systems for moving effluent when culturing saltwater fish and algae, says Katie Kealoha, who co-runs the center with marine science coordinator Dana Hoppe.

“We always try to get the kids to understand things like food security, food systems, and what influences them,” says Hoppe, adding that their community sits within a food desert. The idea, explained Hoppe, is that the principles communicated in the program can be absorbed and applied by students in contexts outside of aquaculture, too.

A newfound and enthusiastic demand
Across the Pacific, aquaponics is burgeoning. The Guam Green Growth initiative (G3), which launched in January 2020, recently developed a community garden in Taloʻfoʻfo in conjunction with an AmeriCorps VETCORPS team and University of Guam (UOG) Sea Grant. The site is home to an aquaponic system that incorporates the “recycling of white goods—appliances, freezers, refrigerators, and that kind of thing—and sticks them into the aquaponic system,” says David Crisostomo, an aquaculture specialist who is jointly supported by Hawaiʻi Sea Grant and UOG Sea Grant. “[It’s] very much a small-scale, backyard, family-use system.”

This is just the start. Crisostomo says there are several more systems planned for communities across the island.

“We’re approaching it with the idea of ‘let’s walk before we run’,” explains Crisostomo. “Let’s start the community up with something they can sink their teeth into, something that they can immediately see as affordable and beneficial to feed their families, to maybe produce more than they need, and then barter that with other farmers.”

Crisostomo says that while the initial cost of assembling small aquaponic systems can be significant, they can be run on the energy of a 100-watt light bulb.

Future projects include a collaboration with the UOG College of Natural & Applied Sciences on an aquaponic system to generate economic data on commercial applications on the island. Crisostomo also says the initiative is looking into vertical systems, which some local hotels are considering installing in the sunlit portions of the buildings.

“Guam does not have a huge landmass to deal with,” he says. “The vertical systems work really well in small footprint areas and can produce quite a lot.”

The new upswing in institutional aquaponics enthusiasm is part of a dramatic and welcome shift in how the government is regarding aquaculture overall, says Crisostomo.
“For the first time in my 40 years working in aquaculture, the government is really supportive. Sea Grant, and NOAA in general, has taken a very supportive stand with aquaculture.”

On the academic side of things, the change in interest is just as explosive, says Fox.

“Ten years ago, there were maybe 5 or 10 peer reviewed publications on aquaponics. And now there are hundreds, and more every year.”

Farming on a loop produces healthy foods while making a relatively gentle environmental ripple, which is welcome news for both people and the places they live. With some tanks, a bit of backyard space, and a little creativity, you too can contribute to that impact.

 

 

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