Pros and Cons of Aquaculture: Is Fish Farming Sustainable?

As the global population is set to reach 9.7 billion by 2050, the sustainability of our food sources has never been more critical. To make things worse, nearly 90% of the world’s marine fish stocks are overexploited or depleted [1].

The stakes are high not only from the quantity of available fish food but also from a nutritional standpoint. Fish is crucial for nutrition. It provides 17% of the world’s animal protein. In the poorest countries, this figure rises up to 26%.

The world’s per capita fish supply reached a new record of 20 kg in 2014, a feat made possible largely by the robust growth in aquaculture, which now provides half of all fish for human consumption. Fish is also a key global trade commodity, as it generates more income to developing countries than other food commodities combined [2].

The crisis of wild fish stocks is not just a crisis in marine biodiversity, it is also a humanitarian one, since about 10 to 12% of the world relies on fisheries for income. Fishing industries employ 60 million people globally and impact 200 million more indirectly [1].

Born out of millennia-old traditions and propelled by recent scientific advancements, aquaculture has seen rapid growth. For decades the industry has been growing and in 2014 it was worth over US$ 160 billion, a trajectory that continues to increase [1].

There are, however, fears that the aquaculture industry is biologically and environmentally detrimental which raises deeper questions into its viability as an industry of the future. Is the practice sustainable enough? Discussing the pros and cons of aquaculture is crucial for evaluating its role in reliable food production.

What is sustainable aquaculture production?

Sustainable aquaculture is a smart way to grow aquatic animals and plants. The Food and Agriculture Organization (FAO) supports the sustainable version of this farming sector. The version where farming aims for efficient food production while caring for ecosystem health, biodiversity conservation, and wellbeing of local communities.

This means employing fish farming methods that maintain water quality, reduce waste, and ensure the ethical treatment of farmed species. Farmers are encouraged to use quality feed and to adhere to appropriate stocking densities to maintain animal health.

When done sensibly, aquaculture aligns with several Sustainable Development Goals (SDGs). Most important ones are helping to fight hunger, improving health, and reducing poverty. Despite this contribution to SDGs, the industry is often missed in global sustainability talks. It gets only one mention in a sustainability goal number 14 – a goal that covers marine resources. Yet, its impact is broader, including freshwater systems and other SDGs linked to poverty and global food security.

Recently, the FAO’s Committee on Fisheries (COFI) took notice of the insufficient attribute. They highlighted aquaculture’s role in food security and socio-economic growth. COFI suggested developing global guidelines for sustainable aquaculture. They stressed the need for best practices in this sector, and it is just about time to do so.

Because the talk of sustainability is what brings us to exploring the advantages of aquaculture. Let’s follow the track and have a look at each one of them before we proceed to its numerous disadvantages.

What are the main pros of aquaculture?

Aquaculture holds promise for sustainable fish food production. It offers a way to meet the rising global demand for fish and more. Here are the main pros of aquaculture we found during our research.

#1 Sustainable food source

Aquaculture has huge potential for stable and scalable food supply, which makes it a key industry that strengthens global food security. From 1997 to 2017, aquaculture production grew from 34 million tons to 112 million tons. This rapid growth has happened mostly in Asian countries [1]. China, for example, has utilized their extensive experience with fish farming to meet the needs of a growing urban population.

But quantity is not all that the industry has to offer. Fish farming has the capacity to specialize in a great diversity of species. Currently, we can grow over 500 different species. And the additional benefit is that these species can be grown on small family farms or even by big enterprises.

Yes, aquaculture is flexible based on the environment, and scalable based on the market demand.

#2 Secures livelihoods & boosts economies

The arguments in favor of aquaculture are that the industry creates jobs for the local community, predominantly in low-income countries that suffer from poverty and poor health. As it stands, between 27.7 and 56.7 million full and part-time jobs are tied to this industry.

The money raised by fish farmers is often used to supply food for families as well as pay for education in an attempt to eliminate the cycle of poverty that besieges poor families. The capital raised and spent in these communities subsequently sees the subject city as a beneficiary due to an increase in activity around the local economy. This can potentially encourage investment into the region from the State budget, which may not have otherwise been viable, particularly for restaurants and the food economy.

What’s more, aquaculture supports various job positions, ranging from fish farmers to seafood processing jobs, employing women and utilizing the knowledge of indigenous communities that have unique skills in local species ecology. The range is great and positive for communities involved.

Aquaculture products from developing countries make up 54% of the global fish trade. The diverse produce generates more income in some regions than any other commodities. Let’s not forget that in some regions, the climate and soil quality doesn’t support many forms of agriculture, but fish farming can still stand a good chance, and even be profitable.

Global demand for aquaculture products is rising, opening doors for expansion, especially outside Asia. This steady increase since 1990 has kept seafood prices stable, which adds to an extra benefit, as this stability has been vital for lower-income countries, where affordable nutrition is crucial.

#3 Protein accessibility

The vast quantities of food produced by fish farmers are positive for communities. With nearly all of wild fish stocks at unsustainable levels, aquaculture is helping to fill the void, offering vital protein to people of all wealth classes whilst reducing the seafood deficit.

With global seafood consumption rising from 9.0 kg per capita in 1961 to 20.2 kg in 2020, it is not just a delicacy but a necessity.

Fish farming is especially vital for impoverished regions where access to quality protein is scarce. FAO data shows that fish is a key source of animal protein, accounting for about 17% globally but exceeding 50% in many least-developed countries.

Fish is rich in essential fatty acids like omega-3s, critical for optimal neurodevelopment in children and cardiovascular health in adults. They are also dense in micronutrients like vitamins A, B, and D, and essential minerals such as calcium and iodine.

#4 Controlled environment and biosecurity

Aquaculture provides a more controlled environment for fish to thrive compared to open-water fisheries. In these controlled settings, it is easier to keep a check on important factors like water quality and temperature, creating an ideal environment for fish growth. This not only makes the fish healthier but also improves the quality of the product for consumption.

For instance, consider a salmon farm where conditions are optimized for the fish to grow well. The water is kept clean, the right amount of feed is provided, and the temperature is just right. 

This setup also allows for better disease control. In an open-water fishery, if a disease breaks out, it can spread rapidly with little to no control. But in a controlled aquaculture setting, there are biosecurity measures in place to prevent, detect, and manage diseases promptly, ensuring a healthier fish population.

#5 Innovation and research

Another beneficiary of a growing aquaculture industry is science. As the supply of farmed fish burgeons, the scientific community is able to better understand the impacts of using the aquatic environment as a food-based resource, which in turn develops a culture for technological solutions to the growing set of issues the marine environment faces.

The more we farm fish, the more we learn. Advancements in aquaculture technology have been on the rise with the efforts of making the industry resilient and sustainable. Think sensors that monitor water quality in real-time, automated feeding systems that are like room service for fish, and even AI algorithms that predict the best harvest times.

This drives the progress in fish farming in a way that enables us to reduce waste, conserve water, and optimize energy use.

#6 Ecosystem preservation

The conventional methods of wild-caught fisheries are often plagued by overfishing and habitat destruction. Additionally, destructive fishing techniques like trawling have dire implications for marine ecosystems, uprooting sea flora and destroying coral reefs. These practices not only deplete biodiversity but also disrupt the ecological balance, leading to long-term negative consequences that extend well beyond the fishing industry.

On the other hand, sustainable aquaculture minimizes environmental impact through calculated strategies such as polyculture, Integrated Multi-Trophic Aquaculture (IMTA), and the use of eco-friendly feeds.

For example, in IMTA systems, multiple species are cultured in a way that the waste from one species becomes a resource for another.

#7 Low carbon footprint

According to organizations like the World Wildlife Fund (WWF), sustainable fish farms produce less methane and carbon dioxide, and require fewer resources when compared to other forms of industrial farming. For example, farmed salmon generates only a fraction of the carbon footprint associated with beef production (extremely polluting on an industrial scale).

The seafood industry is more carbon-efficient than any other animal farming process. The feed-to-stock pressure exerted by seafood production is considerably lower compared to other forms of animal farming. Aquaculture is also less resource demanding when it comes to claiming more land and destroying native ecosystems (virgin forests, grasslands).

According to a riveting study, if we were to meet the world’s additional protein needs in 2050 through aquaculture instead of agriculture, we could save a staggering 730 million hectares of land—equivalent to twice the size of India. This vast land saving could be redirected for reforestation or other climate mitigating strategies.

However, the word sustainable is important in this case, as some aquaculture practices actually contribute to carbon emissions throughout their production process. For this reason, you will find this argument even under our disadvantages of aquaculture.

What are the main cons of aquaculture?

Arguments against the aquaculture industry are gaining ground as science is conducted and technology introduced. It is now common knowledge within the industry that fish farming can cause diseases and parasites to local wild fish populations because of the conditions in which the fish are raised when not focused on sustainability.

But let’s start first with their home and pollution of water bodies it causes…

#1 Nutrient pollution & eutrophication

Consequently, aquaculture operations in open water systems can pollute local water bodies with excess nutrients from fish feed, waste, antibiotics and chemicals which upset the natural biology of the area.

Aquaculture facilities often discharge untreated water, laden with excess nutrients like phosphorus and nitrogen, back into natural water systems. Unfortunately, the outcome of such practice is eutrophication. This phenomenon spurs a massive growth of algal blooms, resulting in not enough oxygen left for fish to breathe and plants to thrive.

We are basically feeding not just the fish in the cages but also ramping up algae growth in the surrounding waters.

One of the worst offenders is open net-cage farming, which usually takes place along coastlines. These operations use big mesh nets to keep farmed fish contained, but guess what can’t be contained? The waste. Antibiotics, pesticides, and a whole lot of farmed fish excrement.

This cocktail of pollutants doesn’t just hurt wild fish; it turns large bodies of water into what are essentially “dead zones,” unsafe for human activities.

The problem is that many aquaculture industries don’t have the technology or the funds to clean up. Although some regulations have been rolled out in recent years to curb nutrient pollution, there is a long way to go. There is some hope, though: research indicates that using quality feed and better system designs can reduce nutrient discharges by up to 50% [5].

#2 Loss of mangroves and wetlands

About 30% of mangrove deforestation in Southeast Asia is directly linked to the expansion of aquaculture ponds—primarily shrimp farming. That is a sad fact.

Mangrove ecosystems are not only biodiversity hotspots but are also crucial buffers against natural disasters like storms and tsunamis. Besides, mangroves are carbon storage powerhouses—storing three to four times more carbon than tropical forests.

Their deforestation not only exacerbates carbon emissions but also significantly impairs carbon sequestration capabilities. In simpler terms, we are losing a critical ally in our battle against climate change. Countries like Bangladesh, Brazil, China, India, Indonesia, Malaysia, Mexico, Myanmar, Sri Lanka, the Philippines, Thailand, and Vietnam have all witnessed significant mangrove destruction due to poorly planned and unregulated shrimp farming practices.

The story of wetlands is the same. Wetlands serve as invaluable buffers against flooding, carbon sinks, and habitats rich in biodiversity. But sadly, in the eyes of many, they are not valuable enough when it comes to generating fast income. In many regions, they are undergoing alarming degradation, much of which can be traced back to aquaculture.

There has been done an extensive study of wetland’s areas in Bangladesh that well documents this recent trend. Wetland areas such as Hardoho Beel, Angrar Beel, Shaoil Beel, and Gopalpur Beel in Bangladesh are severely damaged. What makes situation worse is that many people are under the misconception that aquaculture ponds will prevent flooding in the region, while even boosting fish and agricultural production. This is a sentiment often encouraged by governments across Asian countries, especially in South and East Asia.

But it is not just a problem of Bangladesh. On the global scale, the situation is equally grim. Despite its advantages, the industry’s rapid growth has caused irreversible damage to wetlands, including mangrove forests, around the world.

#3 Escaped and invasive species

Fish farms also have the ability to compromise the native gene pool of local fish when alien species to that particular territory escape. The subsequent interbreeding would not only put the wild fish stocks at risk, but the industry itself, as the real consequences of this are still unknown.

When farmed fish break free, they mingle with native populations, altering the genetic makeup and often introducing new diseases. What might appear as a minor operational hiccup is, in reality, a biological time bomb.

Then we have the issue of chemicals. Fish farms often use antibiotics and pesticides that end up polluting the water, affecting other species and even building up unwanted resistance to medicines along the food chain.

One of the notoriously known escape artists is salmon. Farmed salmon escapes can occur due to storms, damaged nets, or as “leakage,” when couple fish escape throughout the farming cycle. Escaped salmon pose significant threats to native fish populations.

In regions like Atlantic North America and Europe, the gene pool of wild salmon is distinct from that of farmed Atlantic salmon. When their breeding occurs, it results in the degradation of animal fitness and loss of adaptation capabilities to changing environmental conditions. The subsequent fish populations are weaker and more vulnerable to poor health and parasites in general.

Escaped fish also compete with wild fish for food and places to lay their eggs. In some cases, they have even become invasive species, meaning they are actually causing harm to local ecosystems by bringing it out of balance. This has been observed in rivers in British Columbia and South America.

Another issue is the risk of disease spreading from farmed fish to wild fish. This is because water flows freely between the fish farms and the surrounding ocean, allowing diseases to move with the current as well.

To fix these problems, we need stricter rules for fish farms. These rules should cover how the farms are built and operated, how to prevent and deal with escapes. One strong recommendation is to use land-based fish farms that are completely separated from natural water bodies.

#4 Chemicals and antibiotics

To manage bacterial, viral, and parasitic diseases, fish farmers often turn to various chemicals, particularly antibiotics and pesticides. For example, in Bangladesh’s Rajshahi district, a study found that fish farmers used nine different types of antibiotics and various pesticides, including commonly used ones like oxytetracycline and sumithion.

This helps keep fish healthy and increases production, but it comes with risks. For example, 88% of the farmers in the study didn’t know how to properly use these chemicals, and 81% were unsure about the correct dosages. Worse, 37% reported using chemicals indiscriminately, and 72% didn’t know about the potential harm to the environment and human health.

When these chemicals get into the water, they don’t just vanish. They cause long-term damage. Some studies from Asia showed antibiotic residues in water ranging up to 46,100 ng/L for certain drugs. While it is unclear exactly how much this contributes to global antibiotic resistance, the stakes are high.

Over 35,000 people die in the U.S., 33,000 in the EU, and 30,000 in Asia every year due to antibiotic-resistant bacteria. Most of this resistance comes from improper medical use, but we can’t ignore the potential contribution from aquaculture, especially in countries with lax regulations [6].

In the United States and Norway, the use of antibiotics like quinoles is strictly controlled or banned. But in countries like Chile and China, the use of these antibiotics is actually increasing. With the global nature of the food supply, this is a concern for everyone, not just those living near the fish farms.

#5 Greenhouse gas emissions

Although organizations like the World Wildlife Fund (WWF) tout aquaculture’s lower carbon footprint compared to terrestrial agriculture, the devil is in the details. Certain systems use a lot of energy to heat and aerate the water. Additionally, when fertilizers and feed is added in high concentrations to water, they change the composition it would naturally have. Some of the shallow ponds saturated with nutrients emit carbon dioxide and methane in excess [7].

But to determine the impacts clearly and get reliable data is quite difficult, especially since most farms are in quickly developing countries where many rapid changes take place and legal enforcement is lacking behind.

A bunch of studies have been trying to determine the greenhouse gas emissions from freshwater fish farms and the offshore aquaculture operations, but factors like where the farms are located, what fish they raise, and the local environment make a big difference in the amount and type of greenhouse gases emitted.

Plus, an additional challenge is the diversity of farming types, ranging from just farming shrimps or fish to more complex setups like rice-fish cultures and aquaponics. All these farming processes produce greenhouse gases in different ways, and so far the consensus regarding their emission load hasn’t been determined.

#6 Overfishing for feed

Aquaculture is not a solution to overfishing as long as it feeds farmed animals with wild fish.

Ironically, to feed the farmed fish, we often rely on wild-caught fishmeal and fish oil to supply animal protein, thereby exacerbating the problem of overfishing. That’s right—we are fishing to support more fishing. Doesn’t that defeat the purpose if we are trying to protect wild fish populations in the first place?

Each year, about one-fifth of all wild fish caught goes towards making this feed. A report from the Changing Markets Foundation traced the supply chain of this fishmeal and found that this practice links to unsustainable fishing methods in countries like India, Vietnam, and the Gambia. Even well-known European supermarkets sell farmed fish products tied to these harmful practices. Sadly, they often carry even sustainability labels.

The report highlighted that this method is not efficient since it can take up to five kilograms of wild fish to produce just one kilogram of fishmeal. This practice also hurts local fishers. For example, in the Gambia, a large portion of the wild fish catch went to a fishmeal producing plant instead of to the local people who rely on fish as a main food source.

This scenario calls for a closer look and action towards true sustainability and transparency in aquaculture, to ensure we are not causing more harm to our oceans and communities while attempting to farm fish responsibly.

As you can see the pros are often overlapping with the cons of aquaculture operations. The industry is a bit like Dr. Jekyll and Hyde – the same core but different actions. When done sustainably, advantages prevail, when sustainability is pushed behind the economic gains, it can cause lot of harm.

Regardless of the cons associated with the aquaculture industry, it continues to grow at a great rate. To some this is a positive notion as it takes some of the pressure off wild fish stocks, but to others it simply represents a whole new set of challenges for humanity to digest.