The Laser Battle Against Blood-Sucking Parasites of the Deep

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Alf-Helge Aarskog is pacing. Back and forth he walks across the polished hardwood floors of a barge anchored in a fjord off the southwestern coast of Norway. The barge sits alongside one of the world’s largest salmon farms. It’s November and the sky is cloudless, the mountains are snow-capped, the water is a clear sapphire blue. The control room has the feel of a W Hotel lobby with its elegant lighting and spare Scandinavian design.

On one wall are huge monitors streaming video from nine underwater cages nearby. Aarskog scans the footage—masses of salmon swimming in circles like glittering cyclones—and mutters what I take to be Norwegian profanities.

As CEO of Marine Harvest, Alf-Helge Aarskog oversees a quarter of what Marine Harvest says is a $14-billion-a-year global salmon-farming industry. His biggest challenge: sea lice.

Knut Egil Wang/Institute

The cages collectively hold more than 4,000 tons of fish, which in commercial terms amounts to about $60 million worth of seafood. Aarskog is the CEO of Marine Harvest, the world’s largest salmon fishery, with 220 farms in Norway, Chile, Scotland, Ireland, Faroe Islands and Canada. Aarskog supplies his fish—a third of which are certified “sustainably farmed” by the Aquaculture Stewardship Council—to companies including Whole Foods and Walmart and hotels and restaurants worldwide. He controls about a quarter of what Marine Harvest says is a $14-billion-a-year global salmon-farming industry. But lately, something sinister has been sucking away at his profits.

Aarskog has come to this farm off the small island of Frøya to meet his operations manager, who recently reported some bad news. Underwater sensors showed that the feed consumption in some of the cages was declining when it should have been rising. A sample of fish pulled at random from the cages has confirmed the worst-case scenario: Every fish on the farm is in jeopardy.

Marine Harvest site managers like Steinar Snipsøyr keep a close watch on their salmon for signs of sea lice infestation.

Knut Egil Wang/Institute

Many threats exist in ocean aquaculture. A plague of jellyfish can wipe out a cage of salmon in one fell swoop. An algae bloom can starve the fish of oxygen. A breach in the cage netting can result in a mass escape. Aarskog’s problem is worse—and almost imperceptible. Lurking among the captive fish is a tiny nemesis: Lepeophtheirus salmonis, aka the sea louse.

Mature sea lice are gray, lentil-sized crustaceans, also called ectoparasites, that look like small, fanged tadpoles. About a dozen sea lice can kill a fish, clinging to its scales as they consume blood and flesh. Aarskog has been fighting sea lice since he was 14, at his first job at a salmon farm. The industry was still in its infancy, and his boss had him slice thousands of onions and garlic cloves into cages. The homeopathic remedy didn’t work, but the lice problem was limited then. The cages held a fraction of the 200,000 fish typically farmed per cage today.

Each female louse can produce two strings of 1,000 eggs.

Knut Egil Wang/Institute

Outbreaks of lice can travel like storm clouds between neighboring salmon farms.

Knut Egil Wang/Institute

Lice have coexisted with salmon in the wild for millennia, but they didn’t pose a serious problem for free-swimming fish or for small groups of farmed fish. Each female louse can produce two strings of 1,000 eggs, which means infestations spread quickly within concentrated populations of captive fish. Outbreaks of lice can travel like storm clouds between neighboring salmon farms and threaten wild fish migrating through nearby waters. Because they replicate so quickly, the lice are also adept at developing resistance to chemicals and other lice-control treatments. “Superlice” have come to defy nearly every effort to subdue them.

The lice outbreak in Frøya is in its early stages. We see no more than a few lice on the dozens of fish that are pulled at random from the cages, and many are clean. Still, there’s no choice but to harvest the salmon now—before the sea lice population explodes. The salmon in Aarskog’s cages currently weigh three kilos each, only about 60 percent of their full-grown size. All told, that’s a loss of about $24 million, he tells me.

Marine Harvest can easily absorb this loss on a single farm, but the lice have spread to most of Aarskog’s farms. Between 2015 and 2017 his total harvest across 220 farms declined by 12 percent. Some of Aarskog’s competitors have been hit even harder. The problem, he says, has “reached the status of a nightmare.”

Microscopic Foe of the Blue Revolution

Aarskog grew up on a sheep farm on the coast of Norway not far from Frøya. At 6 years old, he was herding sheep up mountains to get to the high pastures. By 8, his father had taught him how to slaughter sheep himself. “I had a great childhood but was working long hours before it is probably legal to work. What do you call it in America? Child Protection Services? They would have been visiting my parents,” he jokes. Now 50, Aarskog is a fitness freak who competes year-round as a trail runner, mountain biker, and cross-country skier. His business generates billions a year in revenue, but he still thinks of himself as a guy from a farm.

Aarskog’s goal now is to help mobilize a “blue revolution,” as he describes it, “in which aquaculture will eventually replace wild-caught seafood and provide sustainable protein to billions of people.” His competitors, he says, aren’t other commercial fisheries but rather big meat producers like Tyson Food and Smithfield—"that’s the market share I’m after.” He cites data on the environmental consequences of meat production, declaring, “grain-fed beef should be forbidden.” It takes about seven pounds of feed to produce a pound of beef, two to produce a pound of chicken, but a pound of farmed salmon, according to Aarskog, requires less than 1.2 pounds of feed.

According to United Nations data, the global demand for seafood will grow at least 40 percent in the next two decades given current population and economic trends. But wild populations of almost every fish species, including salmon, are declining because of overfishing, climate change, and other environmental pressures. “There will be no way to meet the new demand without farming it,” says Josh Goldman, owner of Australis, an aquaculture company. But whether farmed seafood can be sustainable on a mass scale is the subject of much debate.

Marine Harvest hopes to mobilize a “blue revolution” that provides sustainable protein to billions of people.

Knut Egil Wang/Institute

The environmental challenges of salmon farming go well beyond sea lice. Farmers need to manage the fish waste, prevent escapes, and are responsible for harvesting huge quantities of wild fish—anchovies and herring, among them—which provide the oils and meal used in salmon feed production. Aarskog has signed onto goals set with environmental groups, including the World Wildlife Fund, to create a zero-lice, zero-waste, zero-escapes company. “Not long ago, this was a young, cowboyish industry,” says Ingrid Lomelde, policy director for WWF Norway. “But there’s been tremendous progress, a change of mindset: They understand they can’t grow if they aren’t sustainable.” Aarskog also envisions eliminating wild fish from his feed, instead sourcing Omega 3 oils from micro-algae and proteins from plants.

Salmon farming today represents a small part of the global aquaculture industry—cheaper fish like tilapia, carp, and catfish are produced in much larger quantities, largely for Asian markets—but it’s the fastest-growing sector and by far the most profitable. “This is where the big R&D investment and innovation is happening,” says Goldman, who has benefitted from advances in salmon aquaculture even though he raises the white tropical fish barramundi. “The use of energy-dense fish feeds and underwater camera installations—we owe that to the salmon industry. From a tech standpoint, where it goes, so go many other kinds of aquaculture.”

Aarskog knows he can’t sustain his company’s growth, let alone increase it, if he doesn’t first face down his microscopic bloodsucking foe. So he and other industry leaders have mounted a technological arms race against superlice, investing billions in possible solutions, some of which are as strange and improbable as the lice themselves.

Robots, Lasers, and Containment Eggs

We’re shivering on the rim of a cage at a Marine Harvest farm off the coast of Molde, a village south of Frøya. Thousands of fish are circling the top of the cage, jumping and diving as they jockey for feed pellets that are falling like confetti from a suspended plastic hose. The fish don’t seem bothered that it’s 5 degrees below zero Fahrenheit outside, or that among them, puttering darkly, is a mechanical novelty: a robot the shape of R2D2 and twice the height that’s shooting green laser beams in all directions.

The Stingray uses lasers to target sea lice on the bodies of swimming salmon.

Stingray

This device, dubbed Stingray, is one of the more eccentric weapons Aarskog is testing in his war against sea lice. Built by deep sea oil industry engineers specifically for lice extermination, Stingray “watches” the fish via live video feed and uses AI programming similar to the facial recognition software on your iPhone. It identifies aberrations in color and texture on the fish’s scales. When it detects a louse, the bot zaps it with a surgical diode laser beam, the kind used for eye surgery and hair removal. The mirror-like scales reflect the beam, leaving the fish unscathed. But sea lice are gelatinous, roughly the consistency of an egg white, so they fry to a crisp and float away. While laser beams generally travel slower underwater than they do through air, beams of certain colors and wavelengths can travel through water with high accuracy.

Aarskog teamed up with two other giants in Norway’s salmon farming industry, Lerøy Seafood Group and SalMar, to help back the project with $1.5 million in funding. The companies first began testing the robot in 2014, and there are now about 200 devices incinerating lice at farms throughout Norway and Scotland.

Stingray, courtesy Stingray/T.Rasmussen

Still, Aarskog is only mildly impressed with the technology. “It’s a mechanical version of an ancient method of lice control,” he says. The Stingray mimics what so-called “cleaner fish” such as wrasse and lumpsuckers do in the wild, nibbling the lice one by one off of the fish’s scales. Aarskog has been filling his cages with schools of these cleaner fish for years as a way to control lice, but they can’t eradicate big outbreaks.

John Breivik, general manager of Stingray, says robotics radically improve upon the lumpsucker. “For every 100,000 salmon, you might need 10,000 cleaner fish to keep lice populations at bay—or only one to two robotic lasers.” Still, the robots have limits: It’s hard for them to get at lice that hide beneath gills and behind fins. They’re designed to be used as a preventative technology, holding outbreaks at bay, rather than as a reactive technology that can decimate storms of lice sweeping in from a nearby farm. Brevik stresses that the cleaner fish and the robots can work in concert.

Stingray “watches” fish via live video feed and uses AI programming similar to the facial recognition software on your iPhone.

Stingray

When it detects a louse, the bot zaps it with a surgical diode laser beam, the kind used for eye surgery and hair removal.

Stingray

While the fish are better at getting the lice that hide beneath the salmon’s gills, the robots can target the colorless baby lice that cleaner fish can’t see. “It’s a synergy of old and new,” he says. Stingrays achieve about a 50 percent reduction of lice populations in the farms where they’re used, and their AI systems grow smarter and more effective at targeting the lice over time. “The effect is like compound interest,” Brevik says. Aarskog, peering into the icy water of his fish cage as it flickers with beams of light, is less sanguine. “We’ll see,” he says flatly.

Aarskog is understandably wary; he’s spent years testing new approaches without success. About a decade ago, when the lice problem first started getting out of hand, he and other industry leaders were using fish feed laced with emamectin benzoate, a chemical known as Slice that passes through the lining of a fish’s gut and into its tissues, where the sea lice absorb it and die. The chemical worked for a while, but then the sea lice developed resistance. Aarskog and others tried hydrogen peroxide baths, rinsing their fish in the chemical every few weeks as they matured. Again the lice adapted. They tried “flushing”—running lice-infested fish though a kind of aquatic car wash. This was expensive and so traumatic for the salmon that it stunted their growth.

Now Aarskog is testing other mechanical approaches in addition to the Stingray. One is a Beck cage, large enough to hold 150,000 fish but also mobile, so that if fish are threatened by a lice outbreak, the cage can be plunged deeper into colder layers of water where the lice can’t survive. He’s also exploring mesh “skirts” that are wrapped around cages with microscopic holes that lice can’t penetrate, along with better underwater cameras and digital sensors that could help catch outbreaks sooner.

If all else fails, Aarskog is also preparing to quarantine his fish. He’s invested tens of millions of dollars in the development of spherical cages made with solid polymer walls. These cages, called Eggs, are being tested as prototypes in a university laboratory. In the real world, they would be 150 feet deep and 100 feet wide, capable of holding 200,000 salmon, and impervious to the parasites. They look in computer renderings like white plastic UFOs when partially submerged—a jarring contrast to the pristine fjords, but these Eggs and other “closed containment” systems have gained support from environmental groups and coastal communities because they promise to completely confine waste and disease, and prevent escapes.

The technology, though, is costly and complex. The water in the Eggs must be pumped in from deeper layers of the ocean, continually refreshed, and filtered for microscopic contaminants; fans inside the container produce currents for the fish to swim against (salmon can’t build muscle mass in still water); buoy systems are needed to absorb the impact of waves outside the Eggs as clashing currents can make the fish seasick; huge quantities of waste must be captured and processed; exhaustive cleaning and hygiene practices are necessary to keep the container and the fish clean and disease free.

These closed containment systems are the aquatic equivalent of a vertical farm—controlled, hyper-engineered environments on the frontier of food production. Aarskog recently won government permits to put five Eggs in the open water and plans to have them up and running next year, but it’s an expensive victory: Each Egg will cost millions to build and operate. He’s also seeking permits for a similarly costly donut-shaped containment system (dubbed, inevitably, the Donut) which functions much like the Egg, but is designed to generate a stronger, more controlled current for the salmon to swim against—producing “fitter” fish.

For all their risks and complexities, Ingrid Lomelde of WWF Norway applauds the effort: “So far the most promising technology we’ve seen to address the lice problem is closed containment.” It might seem absurd to spend this kind of money to right the wrongs of aquaculture, she says, “if only global demand weren’t soaring, and wild fisheries weren’t in such rapid decline. We’ve lost almost half of the animal life in our oceans over the past 40 years, and today 3 billion people depend on fish for protein. We need sustainable aquaculture to feed them.”


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