To raise fish in captivity is not easy.
A fish farmer has to figure out how to ensure a pond or container has enough oxygen; how to keep birds and other predators away; how to feed the fish, keep them disease free, and manage their waste.
This has not changed since Fan Li was fighting predators—mythical flood dragons that flew away with his carp—at his ponds in China in 475 BCE, when he wrote the first document on aquaculture. What has definitely changed is technique. No longer do aquaculturists insist on releasing fish into a pond without a splash on the seventh day of the second month of the year, as Fan did.
Today, technology has turned aquaculture—the cultivation and harvest of fish, bivalves, crustaceans, algae, and aquatic plants—into the world’s fastest growing food production sector. From 1990 to 2018, global aquaculture production rose 527 percent. The Food and Agriculture Organization of the United Nations (FAO) is betting that aquaculture will be a critical source of nutrition for the world’s population, which is estimated to reach 9.7 billion by 2050.
The challenge is how to farm aquatic species sustainably. Thanks to our ability to share information, we have some foresight into the problems we may face, unlike when humanity took the leap into plant cultivation with wheat about 12,000 years ago, or when we domesticated sheep and goats a few thousand years after, in what is today Turkey. The world’s total human population at the dawn of agriculture was anywhere from four million to 10 million or so—today the population of Tokyo falls around the upper end of that estimate.
The Agricultural Revolution was a gradual process, unplanned, and arising independently around the world. For hunters and foragers to continue their ways of life proved difficult amidst a bunch of people hell-bent on farming. As Colin Tudge wrote in Neanderthals, Bandits and Farmers, “People did not invent agriculture and shout for joy. They drifted or were forced into it, protesting all the way.”
Farming is hard work. Humans had no clue that all that effort would lead to mechanization and industrialization and would transform 50 percent of the Earth’s habitable space into agricultural lands. Nor did they anticipate that irrigating crops would take 70 percent of global water use, or that producing food would directly contribute to 26 percent of global greenhouse gas emissions. The cultivation of cows has been particularly problematic—they generate more emissions than any other animal species except for humans.
As is the case with terrestrial plants and animals, the environmental impacts of growing aquatic species run the spectrum of benign to malign. Bivalves, plants, and algae? Relatively benign. Finfish and crustaceans? Not so much. Feed, disease, and pollution issues plague these industries. Open-net salmon farms, for example, can contaminate the surrounding seabed with waste and pesticides. An overreliance on antibiotics is common in some industries, for instance, in shrimp farming where disease can wipe out 40 percent or more of the product globally in any given year. And farmers of fish—particularly carnivorous species, such as salmon—have traditionally leaned heavily on the world’s wild forage fisheries to make fish meal.
There are moves by these industries to be better, to mitigate pollution through offshore cage farming or recirculating farms—large indoor tanks that make it easier to control pathogens and manage water quality—and to invest in more sustainable, and cheaper, feed. Can these changes be made fast enough to feed a growing human population and protect the environment?
Since 1950, global fish consumption has grown faster than the human population. There was no doubt by the time capture fisheries began stagnating in the mid-1980s that to meet rising consumption, fish—defined by the FAO as fish, crustaceans, mollusks, and other aquatic animals—had to be farmed. And since the 1990s, the growth in global seafood production has come almost entirely from aquaculture.
The FAO, the World Health Organization, and governments around the world have also spent decades convincing people—especially in societies where seafood is less a traditional meal—to eat more fish, because it’s healthy and generally less of a carbon-intensive meal than terrestrial meat. Overall, we’re complying.
In 2018, humans consumed 20.5 kilograms per person of fish—twice the annual amount of the 1960s. In fact, fish (capture fisheries and aquaculture) provided more protein per capita than any other meat: 67 percent more than pork, 44 percent more than poultry, and 220 percent more than beef. Aquaculture provided 52 percent of the food fish that made it to market that year. Fish sales in the United States tallied $401-billion, and more than half was spent on farmed species.
The FAO is achieving its goal of persuading more people to eat fish, yet it also promotes equal access to healthy food and sustainable aquaculture development. This is where it gets tricky: the more sustainable a practice, the more expensive and difficult it is. The resulting protein is pricey and the product becomes a luxury, which runs counter to the FAO’s desire to lean on aquaculture to boost food security.
In fact, aquaculture has deep roots as a means of acquiring and showing off wealth. In Wuxi, China, a monument to Fan Li’s treatise touts fish farming as a wealth generator. Fan Li was filthy rich. His five rules for making money included raising fish from birth to plate.
Today, China raises more freshwater fish—mostly carp—in ponds than the rest of the world put together, because it began the practice so long ago, and because raising freshwater species is generally easier than raising marine species. Since domesticating aquatic species of all kinds is difficult and overall more expensive than capturing them, aquaculture was slow to take off. It only accelerated in the latter half of the 20th century. Technology has helped spur growth, as have rising incomes and urbanization.
In this editorial package, we focus on some basic questions about domesticating aquatic livestock. What will we feed them? How will we shelter them humanely, rather than crowding them into the equivalent of a feedlot? Can we house them without requiring tons of energy? Can we feed 9.7 billion people without destroying the environment?
We are in the middle of the Aquacultural Revolution—there is no going back to eating predominantly wild fish on a global scale. We are systematically domesticating species that will exist solely for human benefit. A domesticated fish is another mouth to feed, another animal dependent, another life form under our control. Are we ready for this?
—Jude Isabella, editor in chief
Read the next story in our special editorial package on aquaculture: “A Short History of Aquaculture Innovation”