what is sustainable seafood?

As our awareness of the impact, we have on the planet and its ecosystems grow, we begin to ask ourselves questions that were previously ignored. Where does our food come from? How is it produced? What’s aquaculture’s impact on the environment? Consumers have begun to seek out “organic” and “sustainable” products, and companies, aware of this, have employed tactics that lead us to believe that their products meet these characteristics, though this is not always the case.

In the seafood environment, sustainability has become even more relevant. Various documentaries, television reports and magazine articles have alerted the world to the impending ecological problem that traditional fishing practices represent: the seas are overstretched. Given the importance that marine ecosystems have for life on the planet, this represents an existential risk for humanity and many other species.

In Seaspiracy, the Netflix film that shook the world in 2021, British filmmaker Ali Tabrizi constructed a piece of work that, although biased, does show that industrial fishing is a terrible threat to our future. The problem with the film begins when the director, who narrates the adventures he endures in order to show us the atrocious world of overexploitation of fishery products, and begins to look for sustainable alternatives. He looks to aquaculture, only to conclude that this practice is no more sustainable than the traditional and that the only option we have left is to completely stop eating seafood.

If you’re a San Francisco hipster with a high salary and surrounded by urban farms, maybe you can heed Tabrizi’s call and give up seafood altogether. That, however, is not an option for everyone.

This year, the world population will reach 8 billion people, and we all need to eat.

It’s estimated that between 14 and 16% of the high-quality protein that we human beings consume comes from seafood. It is the main food source for one billion people. For this vast number of people, giving up fish, shellfish and crustaceans is not a real option.

So, if you saw Seaspiracy and came to the same conclusion as its director, you might want to rethink a few things, starting with, does sustainable seafood really exist?

The fishing problem

Overfishing is undoubtedly a real problem. If we continue to exploit the seas in the way we have done, in a very short time there’ll be nothing left to extract from them. Since the beginning of this century alone, the UN has identified at least 100 marine dead zones. Furthermore, three-quarters of species with commercial value are in some degree of danger due to overexploitation.

Driving entire species into extinction could unbalance marine ecosystems and affect untold numbers of animals, leading the oceans to a large-scale ecological crisis.

Although all forms of fishing involve environmental damage, industrial fishing is by far the most predatory practice. Although they account for a mere 1% of the world’s fishing boats, the large fishing companies monopolize half of all the fishing products.

To achieve this, they cross international waters, spreading environmental damage beyond the coastlines, far from the coasts.

Incidental fishing (bycatch) is a separate problem. Although there are some techniques that reduce it, all fishing for a marketable product causes unwanted capture of species without commercial value but which are crucial for the maintenance of ecosystems. We are not only talking about dolphins or turtles but about fish whose meat is unusable but which are part of the food chain upon which many other species depend.

Of these traditional practices, trawling is the most damaging. It’s a system that requires throwing large nets down to the seabed and literally dragging them along the sea floor to extract the desired product from it. This is how shrimp is caught. It is estimated that for every kilo of this product that is obtained, between 7 and 10 kilos of other species are caught, killed, and thrown back into the sea as waste.

This practice causes the destruction of vast swathes of the sea floor – an area equivalent to the land mass of Mexico… every year!

A solution in Sustainable Aquaculture?

The decline in fishing catch volumes has coincided with an increase in aquaculture production. By 2010, this productive sector surpassed fishing as the main source of seafood production. However, is aquaculture sustainable?

This is a complex question because, to begin with, we would have to have a satisfactory definition of sustainability. What is “sustainable”? The common consensus indicates that a food production activity is sustainable when it can guarantee that future generations will be able to continue enjoying the product in question.

More recently, the issue of environmental footprints has further complicated the equation: the impact any given food source production (or non-food product) has on the environment. The resources we use to produce food are valuable and finite: land, water, food, energy…

Under current standards, the aquaculture that has been practiced for the last 40 years is far from sustainable. That is a fact upon which we can agree with Tabrizi.

There are two general forms of aquaculture: open systems and closed systems. Most current aquaculture production comes from the former. Some producers in open systems install hundreds, even thousands, of cages in the sea. The idea is to take advantage of the infinite flow of water which in theory guarantees quality. The problem is that by breeding millions of individuals, huge amounts of organic waste are also produced that can affect marine ecosystems.

Farms built on land have their own problems: They take up huge tracts of land, often devastating mangroves in the process, and use clean seawater that is then discharged, toxic and dirty, back into the sea in a constant cycle. If these farms did not constantly replenish their water, the levels of nitrogen and other nutrients that are produced by fish and shellfish waste would make the ponds uninhabitable. To keep the water at conditions that allow the development of aquaculture products, it is discarded into the sea or other ecosystems. Discharged water contains very high levels of nutrients (mainly ammonium, nitrite, nitrate and phosphate), but also antibiotics and other chemicals that growers use for cultivation.

Diseases are another important factor: once a virus has infected a farm, it will be filtered into the sea along with the water, and since the farms are usually located very close to each other, every farm in the vicinity ends up contaminated and epidemics occur that can seriously reduce production.

Shrimp is a preferred product of consumers, but its production causes the worst environmental and even social damage.

Yes, shrimp farms are responsible for the loss of 40% of the world’s mangroves but that’s just the start of it. The working conditions of employees in the industry are considered modern forms of slavery. 90% of the shrimp consumed in the United States comes from such farms which are most often located in Southeast Asia, Ecuador, and other Latin American countries.

It is a frozen product (frozen thawed and refrozen several times) whose origin is impossible for the consumer to trace.

Closed systems and a sustainable seafood industry

Not all forms of aquaculture are so devastating to the environment. RAS or “recirculation systems” are closed systems that do not depend on the continuous discharge of water. To keep them in optimal conditions, these sustainable seafood farms use mechanical systems that constantly filter and purify the water.

In this way, the water doesn’t have to be replaced continuously, which means they save huge amounts of water. In addition, the need for dangerous chemicals or antibiotics is minimized. Being closed systems, recirculation farms do not cause ecological damage since the entire production cycle is maintained under controlled conditions, without interacting with other ecosystems.

Another advantage of this system is that it can be installed far from the coasts, which allows for fresh products in places where previously it would have been impossible.

Closed systems have yet another advantage over open: to be profitable they need to be intensive. While a traditional farm produces an average of 4 tons/ha, in closed systems it is possible to produce more than 40 tons/ha.

With that said, the environmental footprint of closed-system farms is not completely innocuous, since large amounts of electrical energy are used to operate the water purification, filtration and recirculation systems, and electricity production is polluting.

Within the closed systems, there is one that stands out for its sustainably harvested seafood, or “safe seafood”, since it has managed to mitigate almost all the damage that we have mentioned in this article. These are biofloc systems, which use microbial communities to keep the water in optimal conditions. These microorganisms do the same thing as filters and purifiers but without using electrical energy. In addition, they serve as a food supplement for cultivated species.

Unfortunately, the jump from university laboratories to production farms has been very difficult for the biofloc system, and very few companies in the world have managed to produce marine species using this system at a profit.

One of the companies who has managed this jump is Atarraya. For more than 10 years, this company has sustainably produced shrimp using this system. Their farm on the coast of Oaxaca has managed to produce 30 tons per hectare, making it a hyper-intensive farm.

Today, Atarraya is taking it one step further by creating the world’s first modular and automated farm: Shrimpbox. They have adapted shipping containers to house small ecosystems in which shrimp can live and grow to commercial sizes, with high density per square meter and without the need for water replacement or the use of antibiotics.

This is, to date, the system that best fits with the current concept of sustainability and responsibly caught fish. However, we still have to work on developing improvements that make it even more sustainable, even more responsible.

Like recirculating farm systems, though to a lesser extent, the Shrimpbox uses significant amounts of electricity to run aeration systems, which provide supplemental oxygen to the large numbers of shrimp that grow inside.

In addition, both Shrimpbox and the rest of the “sustainable” farming systems for marine species have to deal with an additional problem: their food source.

Currently, both shrimp and other marine species produced through aquaculture are fed commercial diets, which use fishmeal and fish oil, in addition to other sources of protein. With fish production declining, the aquaculture industry has come under immense pressure to source feed that is not entirely based on marine species of little commercial value.

Thus, gradually, the manufacturers of fish and crustacean feed have found new sources of protein, such as flours made from by-products of the food processing industry, such as meat, bone, blood, feather, and viscera in addition to vegetables such as soybeans, which are also integrated into the mixture with which aquaculture products are fed.


So, the time has come to answer the question we posed at the top of this article: Does sustainable seafood really exist? The answer is, however, a non-binary one. It’s certainly not a resounding “yes” but neither is it a definitive “no”.

Our footprint on the world is inevitable. Our existence, like that of any species, has an environmental impact. Producing food, including fruits and vegetables, grains and even insects, involves the exploitation of resources, the use of energy and the pollution of the environment.

However, being aware of our impact has led us to strive, ever more determined, for less destructive, more “sustainable”, forms of production. It has forced us to question what it truly means to label your product “Sustainably caught fish”, “Sustainably farmed fish”, and the entire concept of sustainable fishing. Just as the various food industries begin to develop better technology, and as humanity weans itself off its dependence on hydrocarbons, we will be able to reach levels of sustainability that today are only just on the horizon.