Unnatural life and painful slaughter in fish factories

Fishes reared in fish farms are subject to great suffering caused by, among other things, the crowding and idleness of the enclosures, stress during handling, transportation and slaughter.

When fishes are slaughtered, carbon dioxide stunning is still common and legal in the EU. In Norway, carbon dioxide stunning for fish slaughter has been banned since 2012. The gassing is cheap and many fishes can be handled at the same time, but it has serious shortcomings as carbon dioxide causes severe discomfort and stress to the fishes. (1, 2) The method can also render the fishes immobile, making it appear like they are stunned while they are actually conscious. (3) As the stunning is ineffective, there is a risk that the fishes are subjected to exsanguination and evisceration while fully conscious.(3) The fish are then killed by cutting their throats or gills and they bleed to death.

Fishes reared for slaughter are counted by weight and not by number of individuals, so it is hard to estimate how many that are suffering because of human consumption Globally, an estimated 50-150 billion fishes are slaughtered per year, (4) compared to around 70 billion chickens, pigs and other terrestrial animals slaughtered worldwide per year.

Fish factories, like fishing, contribute to the depletion of the oceans, as most of the fishes that are farmed are fed feed that is partly made from wild-caught fishes. (5, 6) Fishing and fish factories are therefore closely linked.

Prolonged death in fisheries

Since fishes are wild animals, they are not subject to the animal welfare legislation and the slaughter and killing requirements for other animals. The catching methods and the handling of fishes after catching and during killing cause great suffering to the fishes. Catching fishes with hooks, nets, trawls and other equipment damages and stresses the fishes and can lead to a very prolonged death. (7-9) Even for those fishes that survive the catch itself, death is prolonged and painful. The most common ways in which fishes die in fisheries are suffocation in the air after being caught or death by strangulation or gutting while still conscious (10-12).

As in fish factories, the fishes caught in the fishery are counted by weight and not by number of individuals, so we do not know exactly how many fishes are involved. It is estimated that around one to two thousand billion (one to two trillion) fishes are caught and killed each year globally in fisheries. (8)

Amazing abilities

There are more known species of fishes, over 30,000, than all other vertebrates combined. The different species of fishes have both common and species-specific behaviors and needs and amazing abilities.

Many fish species have long-term memory, they can learn from each other, think logically and solve different problems. Memory like a goldfish is nothing more than a myth.

Many fishes live in large social groups, but still recognize the individuals in the school.  For example, a guppy can recognize up to 40 other individuals by appearance alone.

Many fishes build nests. They show great flexibility in their nest building. There are also examples of fishes who use tools. For example, cichlid corydoras lay their eggs on leaves and then move them to safer places.

One of the most important senses of fishes is the lateral line organ, which detects currents in the water. The lateral line may be to fish what the eyes are to humans.

A 2019 study showed that the blue streak cleaner wrasse can pass the so-called mirror test. The mirror test is used to assess whether an animal is self-aware. A coloured dot was placed on the blue streak cleaner wrasse, which saw themselves in a mirror. The fish then examined the dot on themselves instead of in the mirror, which is seen as a sign of understanding that it is the fish themselves who is seen in the mirror.(13)

The European Unions authority and expert on animal welfare issues (1) and the Swedish Center for Animal Welfare (2) has in recent years presented reports stating that research indicates that fish can experience pain and suffering.

What is pain?

There are two different concepts used to describe pain: nociception, which is the physical reaction of the nerves and muscles when the body is injured, and pain, which is the conscious experience of it. For it to be considered proven that someone can feel pain, the individual must both have nociceptors (nerve cells that receive pain signals), a central nervous system that processes the information, and react with a behavior which indicates pain. (2)

Evidence of pain in fish

It has only recently been shown that fish have nociceptors (3) where painful experiments have shown that they experience pain as negative. When researchers injected bee venom and acetic acid into the lips of rainbow salmon, they showed clear reactions of discomfort by, among other things, scraping their mouths against the seabed, rocking back and forth, not eating, and breathing faster. They also reacted apathetically to new objects that were given and presented to them. (3-5) and when fish were given the painkiller, morphine, their behavior reversed back to normal. (4)

Fish can, just like other vertebrates, produce morphine-like substances, so-called natural opiates of the body, and their function is presumably to relieve pain. (6) The reason why some researchers long doubted that fish can feel pain is that the brains of fish are structured differently from other vertebrates. For example, they do not have a neocortex, a brain structure that is assumed to be important for the experience of pain in, for example, us primates. (6) However, fish have other parts of the brain that fulfills the same function. In addition, research has shown that the experience of pain does not only take place in one part of the brain but is a more complicated process. (6)

Fish remembers and avoid pain

A study has shown that carps that has escaped after being caught by a hook avoids taking a bait for up to three years post the incident. (7) This clearly indicates that fish getting pierced by a hook is a distressing experience and leaves them with trauma. There have also been similar experiments with cod, where most of them would rather starve than take another bite of the hook. (8) Read more about consciousness in animals here.

Fear

Suffering does not just have to be about physical pain; it also includes fear, anxiety, and stress, to name a few. Through experiments, scientists have concluded that fish can be feel fear. (9) They warned other fish that something frightening was about to happen and after a moment’s consideration, scientists saw how the fish made the decision to swim away from the scene. The time of reflection indicates that it is not a question of reflexive behavior but about conscious consideration. (10) Fear is, like pain and stress, something that most animals benefit greatly from in order to survive and cope in their natural environment.

Stress

The physiological stress response is almost identical in all vertebrates, including fish. (11) Just like other animals, fish can suffer permanent physical damage from chronic stress. (11, 12)

The stress response has evolved as a way for animals to get out of an emergency by either fighting or fleeing. In nature, it is very unusual for an animal to be exposed to long-term stress, and therefore the body is not adapted to cope with it. (12) However, for many animals kept in captivity, long-term and repeatedly stressful situations are common.

Chronic stress has been discovered in fish farms where smaller sized fish are being harassed by bigger ones. (11) Fish that are forced to live in water with low levels of oxygen, high levels of harmful substances and fish that are often transported, handled, or crowded together also show signs of chronic stress. (12) Overcrowding has been shown to increase stress response in farmed salmon and rainbow salmon. (13) A fish exposed to long-term stress eats less, grows slower, has a weakened immune system, and easily gets ill. (12)