Aquafarming: What Is It and What Are Its Negative Effects?

Fish and other marine life are farmed in the billions, in the water-based equivalent of factory farming seen on land.

Explainer Aquaculture Food

Words by

In the underwater equivalent of land-based factory farming, billions of fish and other marine organisms are bred, raised and killed every year, primarily for human consumption. Known as aquafarming or aquaculture, this practice puts profit over the welfare of the farmed animals and has devastating environmental effects.

What Is Aquafarming?

Aquafarming is simply the aquatic alternative to land-based farming. Because it takes place largely out of sight and has expanded rapidly in recent years, there is little public awareness of the massive scale on which marine animals are farmed, or just how intensive the aquafarming industry is. Whereas some land-based agricultural systems are more intensive than others, practically all fish farms in the U.S. are considered intensive enough to be regarded as factory farms. Aquafarming can be carried out offshore, or inland using tanks and ponds. In whichever system they are kept, farmed fish and other sentient aquatic species spend the entirety of their lives in crowded and confined environments, which are extremely detrimental to their welfare.

Fish are the most common aquatic animal to be bred, raised and slaughtered in farming systems. The precise number of fish produced by the industry is unknown, because instead of being counted as individuals these animals are merely measured by their collective mass. But we do know that billions of fish are killed by the aquafarming industry every year. The industry also farms other marine life including crustaceans and mollusks. These animals are measured in tonnes just as fish are, though in 2017, for example, it is estimated that 210 to 530 billion shrimps and prawns, along with 43 to 75 billion crayfish, crabs and lobsters were farmed for food production.

Aquatic plants are also produced by the aquaculture industry, but not on the same scale as sentient marine life. While the nutrition provided by consuming fish is well known, the nutritional benefits of plant-based aquatic food sources are less widely publicized. Research suggests that onshore production of aquatic plants, such as some species of marine microalgae, could make a significant contribution to global food security.

Aquafarming Definition

Aquafarming is the cultivation of aquatic organisms, including fish, crustaceans and aquatic plants. It can be carried out in either marine or freshwater environments.

Is Aquafarming Intensive or Extensive?

Land-based farming systems are categorized as intensive if they use a high input of resources per unit of land area. Extensive systems, on the other hand, use fewer resources per unit of land, and use larger areas of land to produce their yield. Aquafarming is primarily an intensive practice as it involves fish and other marine life being kept in very high stocking densities. In order to maximize profits, huge numbers of fish and other marine animals are crammed into tanks or underwater nets, until the time comes for them to be slaughtered.

Another factor that determines whether aquafarming systems are considered to be intensive or extensive is the extent to which their water is managed. In systems where the water quality is naturally controlled by currents, the farming is considered more extensive. In cases where artificial methods are used to maintain a sufficient quality of water, the system is considered intensive. Water management is required in the majority of aquafarming operations because of the high stocking densities of the animals confined in them. In fish farming, for example, the more fish are kept within a given volume of water, the higher the concentration of carbon dioxide and ammonia, which would have serious health implications for the fish if left unmanaged.

What Are the Negative Effects of Aquafarming?

The farmed animals themselves feel the negative effects of aquafarming most keenly. Kept in densely packed environments, with little opportunity to express the natural behaviors of their species, they live out their lives in a succession of highly stressful situations. If they’re not killed first by injury or disease, their lives are ended when they are subjected to starvation followed by an often inhumane slaughter.

Offshore aquafarming also has severe effects on the ecosystem of the surrounding ocean. As fish feed, pesticides and excessive amounts of feces leach into surrounding waters, they can cause toxic algal blooms and lead to decreased oxygen levels as bacteria work to break down the organic matter. 

Another negative effect of aquafarming is the overfishing of wild fish. Whilst it might be assumed that the aquafarming industry would help protect populations of wild marine life, the opposite is true. Because wild fish are caught to produce fishmeal for farmed fish, aquafarming leads to overfishing and diminishing populations of wild fish. Up to half of the wild fish caught each year are used to produce fishmeal for the fish farming industry.

The negative effects of the aquafarming industry are largely caused by the high densities that fish and other marine animals are kept in. The overcrowded environments these animals live in lead to injuries, the spread of disease, contaminants being released into the ocean and fish being slaughtered in large numbers with little regard for their individual suffering.


As with land-based factory farming, aquafarming involves large numbers of animals being crammed into environments far too small to accommodate their needs. Fish and other marine animals kept in such environments are subjected to psychological stress and are at high risk of disease, physical injury and premature death.

Psychological stress can be caused by hierarchical and territorial issues within groups of animals that would not naturally live in such close confinement. It can also be caused by a lack of enrichment and environmental stimulation. Salmon, for example, are a species that naturally swim great distances, but in the environment of a fish farm they can only swim within the confines of their tank or cage. This stress contributes to their susceptibility to disease.

Sea lice are a common form of disease among farmed fish and are particularly rife within salmon farms. These parasites attach themselves to the fish, feed on them and then detach, leaving serious wounds. These wounds often become infected, causing suffering and often death. When fish are kept in closer proximity than they would normally live in, and in a confined area, parasites such as sea lice are able to spread rapidly and also escape to infect surrounding communities of fish.

Injuries and Death

When large numbers of animals are kept in confined environments there are often social and hierarchical issues and many aquatic species are no different. Many species of fish rely on social hierarchies, but when they are kept in confined environments and fish lower in the hierarchy are unable to distance themselves from those higher up, this can lead to fighting, bullying and fish being injured. Without the option of moving to another area, subordinate fish may die — either of starvation or from their injuries.

Fish Feed

In semi-intensive and intensive aquaculture systems there are far from enough natural food sources to go around, so the animals are fed with processed feeds. In offshore farms excess fish feed is released into the ocean, and as high levels of minerals accumulate in areas of the ocean, encouraging the growth of phytoplankton and depleting the water’s oxygen levels.


Not only does aquafarming disregard the welfare of the farmed animals, but ocean-based aquafarming also has serious implications for surrounding marine life. Along with excess feed, other waste products pollute the surrounding ocean including pesticides, antibiotics and large volumes of feces. These also affect the oxygen concentration of the surrounding waters and encourage toxic algal blooms, presenting a challenge to wild marine life in the area and threatening biodiversity. The environmental implications of aquaculture raise questions as to the sustainability of the practice.

Fish Slaughter

There is limited regulation of the methods used to slaughter fish, meaning that many are subjected to inhumane methods and suffer immensely leading up to their deaths. Inhumane slaughter methods often used to kill fish include them having their gills cut without being stunned first, being left to asphyxiate in air or on ice, being stunned with carbon dioxide and being chilled live or bled out without first being stunned. The slaughter methods currently thought to be most humane are percussive stunning and spiking and then bleeding out the fish, as these quickly render the fish unconscious and insensible before they are bled out.

Fish are not the only animals in the aquafarming industry who are commonly subjected to inhumane slaughter methods. Decapods such as crabs and lobsters are often killed by being chilled or boiled while still conscious. These methods cause extreme suffering in these animals’ final moments of life. 

Aquaculture Industry Statistics

  • The aquaculture industry breeds, raises and kills 178 million tonnes of aquatic animals every year. 
  • The industry also produces 36 million tonnes of aquatic plants.
  • The feeding of the animals raised by aquaculture involved the slaughter of 1.2 trillion other aquatic animals.
  • Globally, over 90 percent of aquaculture takes place in Asia, with China being the largest single producer.
  • In 2020, 76 percent of farmed aquatic animals were finfish.
  • Global aquaculture production tripled in just 20 years between 1997 and 2017.
  • It’s expected that the production of aquatic food will have increased by 15 percent by 2030, and the majority of this increase is expected to come from the aquaculture industry.

What You Can Do

The aquafarming industry involves the breeding and slaughter of billions of sentient animals every year. This is only going to change if demand is significantly reduced. You can play a small part in this by removing seafood from your diet and making the switch to plant-based sources of protein.

One form of aquafarming that should be encouraged is the farming of aquatic plants. As long as it is carried out responsibly, the production of aquatic plants such as algae has the potential to provide a sustainable source of amino acids and omega-3 fatty acids, and to become an important addition to plant-based diets.

Support Us

Independent Journalism Needs You

Donate » -opens in new tab. Donate via PayPal More options »