You’ve heard of agriculture. But today, we’re talking aquaculture
Lesson summary
Hi there, I’m Jeff and this is Plain English, where we help you upgrade your English with current events and trending topics. Today is lesson number 585, so that means JR, the producer, has uploaded the full content to PlainEnglish.com/585.
Coming up today: There are farms on land. There are fish farms in the sea. And now there are fish farms on dry land, too. We’ll talk about exactly how that works, and why, in today’s lesson. In the second half, I show you how to use the English expression “put to use.” And we have a song of the week.
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Fish out of water: Future of aquaculture is on dry land
Agriculture is the process of growing crops and raising animals on land, with the specific purpose of producing food. But there is another way that humans produce their food, and that’s called aquaculture.
Aquaculture is farming, only for fish. Instead of raising cattle on land, fish farms grow fish. The most traditional way to farm fish is called “net pen farming.” A net pen is like a floating cage. And it’s in a natural body of water like a river or an ocean.
In a net pen, water flows into and out of the pen, but the fish are trapped and stay in one area. There are sometimes outer layers of nets that prevent predator fish from entering the pen. Picture a giant mesh ball floating in the ocean, secured to the ocean floor with ropes. Inside the mesh ball is a mass of fish.
The advantage to this approach is, new fish can be grown in natural waters, with the temperature, current, and nutrients that they’re used to, only the fish can’t escape. Fish farming has become very popular in the last half-century. This new popularity coincided with a global increase in fish consumption. Today, the world gets about 17 percent of its animal protein from fish. Per capita, the world consumes 20 kilograms of fish per year. And since about 2018, the majority of that fish has come from farms.
But there’s a problem with net pen farming. A lot of fish in a small area produce a lot of waste in a small area. Fish secrete ammonia through their gills. Too many fish, and the ammonia levels in a local waterway will be dangerously high.
Fish also produce solid waste. That waste typically falls to the ocean floor, where it can harm the ecosystem. Large concentrations of fish are also vulnerable to parasites and bacteria infections that can leak out into other fish populations.
And the pens aren’t perfect. In Washington State, about 260,000 farmed salmon escaped from a net pen, harming the natural population of fish in that area. That led the state to ban farming of many species of fish.
A new approach, though, could make fish farming more environmentally friendly. And it’s not happening in the ocean: it’s happening on dry land.
A fish farm on dry land is a building with tanks inside of it. And the newest tanks are sophisticated enough to mimic the conditions that fish would typically find in their natural environment. Farmed salmon, for example, can practice swimming against a current in a tank.
The water in the tanks can be carefully calibrated with natural salts to mimic the saline conditions in the ocean. Temperature can be carefully calibrated, too. Without annoying things like weather and unpredictable currents, farmed fish can grow in ideal conditions for their entire lives, raising productivity. Their diet and health can be carefully monitored with cameras. If the fish are too hungry, or even too stressed, then small adjustments in temperature and food can improve their conditions.
Many fish migrate. They hatch in one set of conditions and, as they grow to adulthood, they migrate to other conditions. For example, salmon hatch in fresh, calm water. As they grow into adults, they learn how to swim against the current. And only as adults do they move into saltwater. An inland fish farm can mimic this migration, too. As fish grow to maturity, they can be transferred to other tanks with other sets of conditions.
Inland farming also solves the problem of waste. Waste from fish in tanks can be extracted. Instead of polluting a waterway, the waste can be separated from the water and put to use , generating renewable energy or as fertilizer for other crops. The water can be consistently monitored, treated, and recycled. Farmed fish in tanks require far less water than farmed fish in oceans or rivers.
There’s another benefit. Many species of fish are very picky: they need to be grown in specific conditions that are not found just anywhere . So with traditional net pen farming, fish are farmed near their local habitat and then shipped around the world—that shipping is often by plane.
But if sophisticated tanks can mimic local conditions, then farms can be located closer to consumers, reducing the cost and environmental damage of shipping fish around the world.
New land-based aquafarms are not cheap. They require a heavy investment in infrastructure—the tanks, the tubes, the feeding systems, the water treatment facilities—that all costs a lot of money. There are also different expenses. While a net pen farmer might have to spend money on shipping, on antibiotics, and might waste money with unconsumed food, a land-based farmer would have to spend money on utilities, salts, and equipment maintenance. It’s early days for land-based aquafarms, and the industry is still finding its feet.
Still, there’s momentum. A facility called Salten Smolt opened in far northern Norway. The 7,000-meter building can produce 8 million juvenile salmon each year. And Iceland is breaking ground on an enormous facility that will use geothermal energy to power its production.
Why only salmon?
Before this, I knew that fish were farmed. But I had no idea how it was done. Literally—I had no idea. I didn’t know about net pens and I certainly didn’t know about dry land farming.
I was curious why so many articles talked about salmon, and so few talked about other species of fish. There’s a reason. Salmon are relatively expensive fish, so there’s more room to save money than on a cheaper species. They’re also very particular about their conditions. So the transportation savings are greater with salmon, too.
That made me wonder—if this works for salmon, a relatively expensive fish, then is it happening with lobster, a very expensive fish? It’s not. Mature lobsters are cannibalistic. They’ll eat each other if kept in small tanks. So to farm lobster, each would have to be kept in its own cage—that raises the cost and complexity.
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