catching on

Could offshore aquaculture make fish farming more sustainable?

Advocates say it's the future of fish farming, but environmentalists warn about potential impacts
A diver checks a net holding thousands of fish at an aquaculture farm off the coast of Corsica.
A diver checks a net holding thousands of fish at an aquaculture farm off the coast of Corsica.
Photo: BORIS HORVAT/AFP via Getty Images (Getty Images)
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Fish farms, now mostly operating out of tanks on land, are testing the waters in the deep ocean.

With fewer wild fish to catch in the open sea, a new industry is emerging to farm them there instead. Using technology like sensors and cameras, companies are building giant floating farms miles offshore.

Advocates say this is the future of fish farms, which now account for the bulk of the fish we eat. Fish farming has been fraught with issues, from crowded pens to the use of antibiotics and GMO feed. But in the ocean, there’s more room for fish to spread out and contaminants to dissolve, they say. And industrial offshore fish farming also gives depleted fish stocks a chance to replenish.

“Going forward with the planet you’ve got two choices: Mandate that everyone become vegan and see how well that goes, or move the population towards more efficient forms of animal protein production,” said Neil Sims, founder of Ocean Era, a US-based offshore aquaculture company.

But critics say farming offshore comes with the same problems as doing it on land—plus others that are unforeseen. Last month, several environmental groups filed a challenge in federal court against a permit for a facility 40 miles off the coast of Florida owned by Ocean Era. The Environmental Protection Agency, they argue, did not properly vet the potential harm from wastewater and fugitive fish from the offshore farm. Ocean Era dismissed the legal action, saying that the allegations are not based on science.

Farmed fish are taking over your dinner plate

More than half of the seafood consumers eat these days comes from a farm, according to the UN Food and Agriculture Organization (FAO). In 2022, the industry is expected to produce 92.2 million tons of fish worth $178 billion (pdf).

And fish farming is expected to keep growing. Global fish consumption has increased by 122% since 1990. Meanwhile, the size of legal wild fish catches has shrunk by more than 60% since 1974.

That’s why the FAO estimates more than 60% of the fish we eat by 2030 will be farmed. The agency believes aquaculture will be key to meeting future food demands sustainably. Fish provides animal protein that could substitute more carbon-intensive meat.

So far, aquaculture on land is the most common form of fish farming, the FAO reports (pdf), but advocates say offshore facilities are more environmentally friendly for salt-water fish.  

Land-based systems rely on controlled aquatic environments, which require high amounts of energy. “On land, you have to pump the water, provide the oxygen, provide for the filtration of the water…everything costs energy,” said Sims. Offshore, the ocean takes care of a lot of that, he adds. “Why would we be moving a system from the ocean where you have natural tides, the capacity of the ocean ecosystem that can provide the water, the oxygen, the nutrients…why would you not use that?”

Offshore farms can also produce larger amounts of fish. Ocean Era’s commercial partner farms harvest around 300 tons of fish from one 10,000 cubic meter pen, compared to 50-cubic meter pens that harvest about three tonnes of fish per pen on land, Sims estimates.

But offshore presents its challenges. Farms are miles away from land, requiring an industrial setup in places with no infrastructure.

What does it take to farm fish in the middle of the ocean?

In one word, technology. Cameras and sensors, along with remotely operated vehicles (ROVs) are being used by companies like Ocean Era to determine when fish are hungry or move pens to protect them when there’s a storm.

Hawaiian Kanpachi fish, a type of tropical yellowtail, are farmed by Ocean Era.
Hawaiian Kanpachi fish, a type of tropical yellowtail, are farmed by Ocean Era.
Photo: Courtesy Neil Sims/Ocean Era

The company runs demonstration and research projects using robotics and remote controls developed with Forever Oceans, a spin-off from Lockheed Martin. The team has developed tests far out into the Pacific Ocean, in waters 6,000 feet deep, to harvest Kanpachi, a type of tropical yellow-tail native to waters off Hawaii. “Our research director used his iPhone to watch video of the pen system, switch on the cameras, the generator, and the pumps. He could do it all from anywhere in the world connected to the cloud,” said Sims.

Here’s what Ocean Era’s experimental system looks like out at sea:

Ocean Era’s experimental Aquapod for offshore aquaculture. A copper-alloy meshed pen is submerged 30 to 50 feet deep to farm fish with no significant impacts to ocean ecosystems.
Graphic: Clarisa Diaz / Quartz

Fish factories at sea

Offshore farm proponents say technology will allow them to scale up in coming years, pushing industrial offshore fishing towards industrial production.

The fisher of the future is “probably going to be sitting down in front of a big bank of computer screens” monitoring fish behavior through AI and machine learning that can tell when the fish are hungry, says Sims.

But the industry is not there yet. Offshore aquaculture projects have a harder time finding investors because the ocean is seen as a black box. “If you’re on top of the water, the only way you understand if there’s a catastrophe going on underneath is if you have a sensor in the water telling you, or you see a dead fish,” said Jonathan LaRiviere, head of Scoot Science, a California-based consulting firm.

Companies will also have to assuage regulators—and the public—that their practices are sound. “It’s the wild west because you’re doing something in the ocean and people get away with so much,” he added. His company’s tools provide dashboards that show ocean patterns and other variables at a farm’s site, which can be used to manage risk and provide data to third parties, like investors, regulators, or environmentalists.

Ocean Era’s commercial system for offshore aquaculture arrays fish pens connected to a single-point mooring. Each pen is 10,000 cubic meters and holds 150,000 fish. A seaweed is grown next to the pens.
Graphic: Clarisa Diaz / Quartz

Then there’s the issue of managing the fish. Though they are in the middle of the ocean, they still have to be fed and kept healthy like farmed fish on land, no easy task 30 to 50 feet underwater.

Ocean Era is experimenting with soy-based feed, and others are looking into other types of fish food with ingredients like marine microalgae. The industry is also coming up with robust net mesh pens that can withstand high-energy offshore conditions to prevent fish from escaping. To avoid changing the genetics of wild fish stocks, companies like Ocean Era also plan to grow the same kind of species as found outside their nets.

So far, it’s hard to measure whether the industry gets better marks than farms on land. Each farm must be taken on a case-by-case basis depending on their management practices, according to Andrew Leingang, an independent expert.

Whether fish farms are on land or offshore, Leingang, who’s been in the industry for five decades, predicts aquaculture will likely replace fishing in the future. “We never go fishing because we always catch,” he said.