THE LIFE OF an Atlantic salmon is one long, gruelling road trip. Born in coastal rivers in Europe, North America, Iceland and Russia, once the young salmon hit adolescence they head out of their natal waters to the frigid North Atlantic, where they gorge themselves on squid and krill. Once they have built up their energy reserves, the salmon use the Earth’s magnetic field and their finely honed sense of smell to find their way back upstream to the exact same riverbed they were born in, where they spawn the next generation of salmon. By the end of this journey, which can cover several thousand kilometres, the fish are so exhausted that many of them perish. A couple of years later the next generation of salmon will be old enough to start the cycle all over again. You’re born, you swim thousands of kilometres, you die.
But inside a sprawling white-panelled factory on a sun-baked former tomato field south of Miami there are hundreds of thousands of Atlantic salmon leading lives that would leave their wild relatives utterly baffled. These salmon are born indoors and die indoors, spending their lives cycling between a series of vast circular tanks that together hold more than 60 million litres of water. Some of the tanks are filled with freshwater, to mimic rivers, while others contain seawater drawn from the Atlantic Ocean, which lies 24 kilometres to the east of the building. According to Thue Holm, chief technology officer of Atlantic Sapphire – the Norwegian firm building the plant – by the end of 2022 the facility located in Homestead, Florida, will be able to produce approximately 10,000 tonnes of salmon a year. When it is completed it will produce a sizeable chunk of the US demand for fresh salmon.
As you might expect from one of the people behind the world’s biggest experiment in land-based fish farming, Holm is convinced that the future of food lies in the oceans. He might have a point. Oceans cover 71 per cent of the planet’s surface, but at present provide us with only about two per cent of our total food and around 15 per cent of all the animal protein consumed by humans. According to the EAT-Lancet report – a wide-ranging study that attempted to pinpoint what the best kind of diet would look like, in terms of the planet’s health and our own – seafood is the one source of animal protein that we should be eating more of. The report estimated that a global shift to a “planetary health diet” that emphasises fruits, vegetables, nuts and wholegrains would also require more than double the current levels of fish production.
Fish aren’t simply a much healthier source of protein; they have a relatively small impact on the environment too. Compared to most land animals, the Atlantic salmon swimming in Holm’s farm are remarkably efficient machines. Since they are cold-blooded and are supported by the buoyancy of water, fish can channel more of their energy into growth, which means they need fewer calories from food than other livestock. It takes about 1.15 kilograms of fish feed to produce a kilogram of farmed salmon – significantly lower than any commonly farmed land animal. It’s the same basic reason why lab-grown meat companies are opting to grow beef in bioreactors: more efficient methods of meat production should come with lower greenhouse-gas emissions. In a world of 9.7 billion people in need of a nutritious, readily available and sustainable source of protein, fish look like one of our best bets.
So where are all these fish going to come from? Not the open ocean, where almost 60 per cent of widely eaten fish are already being fished at their maximally sustainable limits. Wild-capture fishing has chipped away at the ocean’s fish populations, leaving many species badly depleted. In the United States, salmon used to be found in almost every single coastal river northeast of New York’s Hudson, but now the country’s only remaining wild populations occupy a handful of rivers in Maine. The same story repeats itself almost wherever you look in the water. In 2010 the total mass of Pacific bluefin tuna capable of breeding reached its lowest-ever recorded level – just 11 per cent of its 1952 numbers. In 2015 the World Wildlife Fund released a report revealing that overfishing, habitat destruction and climate change had caused fish populations to fall by nearly half between 1970 and 2012. The oceans aren’t able to meet our current demand for fish, let alone feed future generations.
“Hunting and gathering out of the ocean is a joke. We haven’t hunted and gathered most of our food on land for three thousand years,” says Kevin Fitzsimmons at the University of Arizona’s College of Agriculture and Life Sciences. The alternative, to Fitzsimmons, is obvious. Rather than pluck fish out of the sea, why not repeat what we already do with livestock and crops: grow them intensively at scale? Globally fishing has been heading in this direction for decades. In 1961 farmed fish made up about five per cent of the world’s entire seafood production, but since the late 1980s fish farming, also known as aquaculture, has boomed. In most aquaculture, farmed fish are kept in net pens – large circular cages usually made from steel or plastic, anchored to the ocean floor or the bottom of freshwater ponds or lakes. In 2013 the volume of seafood produced in this way overtook wild capture for the first time, and since then the gap has continued to grow. Since the mid-1990s the world’s total production of wild-caught fish has plateaued, while the amount of fish coming from farms has more than tripled. The aquaculture industry has grown up exceptionally fast. “What we did with terrestrial agriculture in three thousand years we have done in aquaculture essentially in the last thirty,” says Fitzsimmons.