On the island of Hawai‘i, about a half mile off Keāhole Point near Kona, nine large net pens teem with hundreds of thousands of kanpachi (Seriola rivoliana, or longfin amberjack). Blue Ocean Mariculture’s kanpachi fish farm is the only commercial open-ocean aquaculture operation in the United States, and it may be a model for an industry that many believe is primed for growth.
“We have the expertise, the technology, and the entrepreneurs who are ready,” says Kat Montgomery, the seafood, aquaculture, and ocean policy director for ESP Advisors in Washington D.C. “In the next 10 years, I believe we’re going to see expansion all over the country, with Hawai‘i leading the way.”
However, critics argue that expanding offshore aquaculture is short-sighted and could lead to the spread of disease, pollution from waste streams, and fish escapes that could threaten native populations. Massive escapes in open-ocean salmon farming operations in North America and Norway over the past two decades, as well as outbreaks of sea lice that threaten wild populations, lend credence to concerns over environmental impacts.
While offshore aquaculture has a contentious history, the National Oceanic and Atmospheric Administration, U.S. Environmental Protection Agency, and other organizations are ensuring that little environmental impact occurs through the advancements in technology with evidence-based science and improved practices. They promote open-ocean aquaculture as a more climate-resilient means of producing animal protein than land-based agriculture, and a necessary piece of the puzzle to address the climate crisis while feeding a growing population.
Despite the debate, trends show that aquaculture (both nearshore and offshore) is a growing portion of global seafood production.
Aquaculture accounted for 52 percent of the fish eaten globally in 2018, according to the Food and Agriculture Organization, with that percentage expected to rise to 60 percent by 2030.
The U.S. lags the major aquaculture producing countries, ranking 17th, and imports most of its seafood. About 50 percent of imports are produced via aquaculture in countries with less stringent environmental regulations.
But Hawai‘i, with its favorable offshore growing areas and a history and culture tied to the ocean, may provide the stage for a new model of sustainable seafood production.
Blue Ocean produces about 800 metric tons of kanpachi annually. They sell most of the fish to high-end restaurants, with about half sold in Hawai‘i markets and half shipped to the continental U.S. Production begins at an onshore hatchery, where hatched fry grow for three months until they’re large enough for transfer to the offshore pens. The fish grow offshore for another 12 months to about five and a half pounds before they’re harvested for market.
Blue Ocean Mariculture CEO Dick Jones believes Hawai‘i can be a leader in creating a responsible and sustainable offshore aquaculture industry.
“Where Hawai‘i has been in aquaculture, starting as a pioneer with fishponds centuries ago, to where we are today, doing commercial-sized aquaculture ventures,” Jones says. “People in Hawai‘i see a critical need for food self-sufficiency, and we’ve got such a vast coastline and outstanding water quality for growing fish offshore.”
Because of the unique bathymetry of the Hawaiian Islands, deep-water offshore conditions occur close to the coast. Blue Ocean net pens are anchored within clear sight of the Kona airport, but they’re also in deep water—about 220 feet—in dynamic areas with strong currents that can help disperse waste. In the shallow Gulf of Mexico, another area where offshore aquaculture is developing, fish farmers have to go 40-50 miles out to find similar conditions.
Neil Sims, a marine biologist and the CEO of Ocean Era, a Hawai‘i-based mariculture company, says the advantage of offshore aquaculture is that it can grow with market demand, and do so with a minimal environmental footprint.
“As you move into deeper water further offshore, inputs are rapidly assimilated and become part of the ecosystem,” Sims says. “If that’s in a concentrated bay, it would be pollution. But out in the open ocean, it’s nitrogen and phosphorus, which become the drivers for primary productivity.”
Dr. Neil Frazer, researcher with the University of Hawai‘i’s School of Ocean and Earth Science and Technology, argues that “dilution is not the solution to pollution.” He says the history of large-scale salmon operations shows that open-ocean fish farms inevitably breed diseases that cause wild fish to decline.
“Sea-cage aquaculture is a recipe for ecological disaster,” says Frazer. “These operations always expand until their effects on wild stocks become impossible to ignore, and by that time the damage is very difficult to undo.”
However, a recent study in Panama shows that operations in deep water with strong currents and high rates of flushing have little impact on water quality and result in modest increases in nutrients in seafloor sediment.
Dr. Rod Fujita, lead senior scientist with the Environmental Defense Fund, says technology and monitoring advances have improved the environmental performance of aquaculture, but more research is needed to ensure it can be done sustainably in offshore environments. However, he is encouraged to see the move toward integrated multi-trophic (IMTA) aquaculture (a balanced system that provides the by-products of one cultured species to another), incorporating seaweed, shellfish, and lower-trophic herbivorous fish species.
“You’re basically creating a mini ecosystem,” says Fujita. “Finfish create nutrient pollution, and seaweed takes out the nutrients. Then, fish remove oxygen from the water and emit carbon dioxide. Seaweed removes carbon dioxide from the water and produces oxygen. It’s a perfect synergy developed over billions of years in the ocean that humans are now figuring out how to mimic.”
Sims and Ocean Era are developing an IMTA project about two miles off O‘ahu’s Ewa Beach that would combine farming of two native Hawaiian fish—the herbivorous nenue (Kyphosis vaigiensis, or brassy chub) and the carnivorous moi (Polydactylus sexfilis, or sixfeeler threadfin)—with a variety of limu, or seaweed, species. The limu will be used to co-feed the fish, reducing use of imported fish feeds.
The project has a unique design that allows the fish pens and limu arrays to swivel with the currents, so the limu is always downcurrent from the fish, allowing limu to capture nutrient-rich effluent coming from the fish pens.
Walter Ritte, a Hawaiian activist and founder of the nonprofit group ʻĀina Momona, believes Hawaiians should look to traditional solutions to food sustainability. Ritte has worked for decades to restore Hawaiian fishponds, or loko iʻa.
“If you live on a tiny dot in the middle of the Pacific and you want to feed people from the ocean, you have to be really smart on how you do that or your resources are going to disappear in no time,” says Ritte.
Ritte points to the ingenuity of fishpond design, such as building ponds around coastal groundwater springs where limu grows abundantly. Herbivores, such as mullet, feed on the limu and don’t require feed inputs. Fishponds also use carnivores like barracuda to control for disease among the mullet.
“Fishponds are a sustainable, long-term way of feeding our people,” says Ritte.
Tori Spence-McConnell, the Pacific Islands regional aquaculture coordinator for the National Oceanic and Atmospheric Administration, says the renewed interest she’s seeing for aquaculture in Hawai‘i reflects a sustainability mindset.
“Many farm operators in Hawai‘i focus on food self-sufficiency and security,” says Spence-McConnell. “Whether it’s trying to do integrated multi-trophic aquaculture, or just raising species that can serve multiple purposes.”
The debate over the role of offshore aquaculture in Hawaiian seafood is likely to heat up as more projects are launched, and the need grows for more locally produced sustainable seafood.
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