Fish slaughter is the process of killing fish, typically after harvesting at sea or from fish farms. At least one trillion fish are killed each year for commercial consumption. Some fish harvesting uses controversial methods like suffocation in air, carbon-dioxide stunning, or ice chilling that have been called inhumane by many organizations such as the World Organisation for Animal Health. However, due to many cultures' reliance on fish, some alternative methods of slaughter have been developed, including percussive stunning, pithing, shooting, and electrical stunning. While these methods are considered effective, they still face criticism, with some arguing that no method of fish slaughter can ever be truly humane.
According to the Food and Agriculture Organization (FAO), a total of 156.2 million tons of fish, crustaceans, molluscs, and other aquatic animals were captured in 2011. This is a sum of 93.5 million tons of wild animals and 62.7 million tons of farmed animals. 56.8% of this total was freshwater fish, 6.4% diadromous fish, and 3.2% marine fish, with the remainder being molluscs, crustaceans, and miscellaneous. [1]
The number of individual wild fish killed each year is estimated as 0.97-2.74 trillion (based on FAO tonnage statistics combined with estimated mean weights of fish species). [2] The FAO numbers do not include illegal, unreported and unregulated fishing, nor discarded fish. If these are included and over-reporting by China subtracted, the totals increase by about 16.6% to 33.3%. [2] A similar estimate for the number of farmed fish slaughtered each year is 0.037 to 0.120 trillion. [3]
Mid-sized trout farms in the UK may process more than 10,000 fish per hour. They are often operated by only a few people, and it may be necessary to kill trout on short notice or even at night. [4]
The main argument against fish slaughter, and inhumane slaughtering practices, is that fish can feel pain. [5] [6] Sentience is defined as consciousness and an ability to perceive feeling. The degree of fish sentience is a debated topic in many countries. [7] The apparent differences between fish and humans have led to fish welfare being often overlooked in ethical discussions. [8]
Research on fish suffering during slaughter relies on measures to indicate when fish are stressed. Some indicators used by welfare studies include [9]
Following electric stunning, as fish gradually resume consciousness, they begin to make rhythmic gill-cover movements. Based on EEG correlations, it is believed that stunned fish remain insensible until they have resumed rhythmic gill patterns. [10] This can be used as a convenient assessment tool for the effectiveness of electric stunning. [4]
Fish cognition is also more advanced than commonly believed. [8] For example, in studies, some fish showed a capability to remember other fish and places. [11]
In 2004, the European Food Safety Authority observed that "Many existing commercial killing methods expose fish to substantial suffering over a prolonged period of time." [12]
The Aquatic Animal Health Code of the World Organisation for Animal Health considers the following slaughter methods inhumane. [13] Some ethicists have gone further and argued that there are no available humane slaughter methods for fish. [14]
Air asphyxiation is the oldest slaughter method for fish and is considered inhumane because it can take the fish over an hour to die. [9] One Dutch study found that it took 55–250 minutes for various species of fish to become insensible during asphyxiation. [15] Fish that evolved for low-oxygen environments take longer to die. At higher temperatures, fish lose consciousness more quickly. [16]
Meat quality and shelf-life are also diminished when this method is used. [9]
Also called live chilling, the ice bath method involves putting fish in baths of ice water, where they chill and eventually die of anoxia. Because chilling slows metabolic rate and oxygen needs, it may prolong the duration until death in some instances, with some cold adapted species taking more than an hour to die. [9] On these grounds, the Farm Animal Welfare Council's 1996 report on farmed-fish welfare stated: "The cooling of live trout on ice after they have been removed from water should be prohibited." [17] In contrast, later research suggested that for warm Mediterranean species such as sea bream and sea bass, the method might at least be preferable to air asphyxiation, with fish showing lower levels of stress indicators. [9] Research in 2009 showed that ice water is faster and less stressful than anaesthetics for killing tropical ornamental fishes like zebrafish. [18]
Most often applied for salmon and trout, CO
2 narcosis involves filling the fish water with CO
2 to produce acidic pH, which injures the brain. The procedure is apparently stressful, as evidenced by fish swimming vigorously and trying to escape from the tank. CO
2 immobilizes the fish within 2–4 minutes, but the fish remain conscious until subsequent stunning or killing. [9]
Salting involves application of salt to the container holding the fish, the salt applied should be just enough to weaken the fish. Salting of fish as a slaughtering (killing method) is only applicable to freshwater species.
Exsanguination is the process whereby an animal is cut so that it bleeds to death. Fish are cut in highly vascular body regions, and the process is stressful unless the animals are unconscious. If not stunned, according to behavioral and neural criteria, fish may remain conscious for 15 minutes or more between the time when major blood vessels have been cut and when they lose consciousness. [12] [19] Eel brain activity may not cease for 13–30 minutes after decapitation, and some fish may remain sensible for 20–40 minutes after evisceration. [20]
In evisceration without stunning, the fish is simply eviscerated alive without being stunned. The fish is instead restrained until it stops struggling.
Also known as knocking, percussive stunning involves hitting the fish's head with a wooden or plastic club, called a priest. One or two appropriate blows can disrupt the brain sufficiently to render the fish insensible and potentially even kill it directly. However, applying this method correctly requires training and effort. Percussive stunning must be applied one fish at a time and so is typically only used for large fish, such as salmon and trout. If the operator is skilled, percussive stunning can be among the most humane methods and can also yield high meat quality. [9] One comparison of slaughter methods found that percussive stunning had the best welfare performance as measured by low hematocrit, low plasma glucose, low lactate, and high muscle energy charge. [21]
For some fish species, there are automated percussive stunning tools, such as a pneumatic club for salmon. [9] However, building an automated machine to process, orient, percussively stun, and bleed bulk quantities of small fish would be difficult. [4]
Pithing, also known as ikejime (or ikijime), involves sticking a sharp spike through the brain of the fish. If done properly, it can kill quickly, however, if the operator misses the brain, the results may be stressful for the fish, which is why resources such as the ikijime.com database [22] have been developed to define the brain location of many popular fish species. As with percussive stunning, spiking is used to kill one fish at a time and so is mainly used for large species such as tuna and salmon. [9]
Shooting large fish is also possible. [13]
Electricity can be more humane than alternatives if applied correctly. [23] In addition to potentially producing unconsciousness quickly, stunning reduces the stress of restraint and being removed from water. [24] : 167–168
If electrical parameters are not optimized, electrical stunning may produce immobility without loss of consciousness, which is inhumane. [9] [20] [24] : 167 There is little public data comparing optimal stun settings found by researchers with the settings used in commercial slaughter operations, so it is unknown how effective real-world stunning is. [25] : 7 In addition, proper stun parameters vary significantly by species. [24] : 168
Electricity may introduce bleedspots, so proper settings are required. [23]
In June 2024, the Centre for Aquaculture Progress, a non-profit organization dedicated to fish welfare in Europe, oversaw a comprehensive study of European consumer attitudes to electrical stunning. The study found that 83% of consumers endorsed pre-slaughter electrical stunning for sea bream and sea bass and that 80% were prepared to pay more for fish that had been slaughtered humanely. [26]
Systems have been developed to slaughter large numbers of fish whilst maintaining welfare standards.
A paper published by Jeff Lines and his collaborators in 2003 announced that stunning trout for 60 seconds in an electric field of 250 V/m r.m.s. with a sinusoidal waveform of 1,000 Hz rendered them permanently unconscious without degrading meat quality. [4] A stunning system, called HS1, has been developed in accordance with Lines' study. The system first stuns fish and then keeps them unconscious, through electronarcosis, until death. The machine has been widely adopted in the UK, processing an estimated 80% of all UK trout killed for meat. [27] According to the Humane Slaughter Association's James Kirkwood: "Before ten years ago there was no way to humanely kill farmed fish en masse – they died slowly through suffocation when harvested from the water. This welfare benefit affects millions of fish." [28]
No welfare standards exist for the trillion or more fish harvested from the wild each year. [29]
Since 2008, Norway has banned CO
2 stunning. [20] By January 2010, 80% of Norwegian fish-slaughter facilities had switched to either percussive or electrical stunning. [30]
Germany has banned use of salt or ammonia baths. [20]
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Aquaculture, also known as aquafarming, is the controlled cultivation ("farming") of aquatic organisms such as fish, crustaceans, mollusks, algae and other organisms of value such as aquatic plants. Aquaculture involves cultivating freshwater, brackish water, and saltwater populations under controlled or semi-natural conditions and can be contrasted with commercial fishing, which is the harvesting of wild fish. Aquaculture is also a practice used for restoring and rehabilitating marine and freshwater ecosystems. Mariculture, commonly known as marine farming, is aquaculture in seawater habitats and lagoons, as opposed to freshwater aquaculture. Pisciculture is a type of aquaculture that consists of fish farming to obtain fish products as food.
Fish farming or pisciculture involves commercial breeding of fish, most often for food, in fish tanks or artificial enclosures such as fish ponds. It is a particular type of aquaculture, which is the controlled cultivation and harvesting of aquatic animals such as fish, crustaceans, molluscs and so on, in natural or pseudo-natural environments. A facility that releases juvenile fish into the wild for recreational fishing or to supplement a species' natural numbers is generally referred to as a fish hatchery. Worldwide, the most important fish species produced in fish farming are carp, catfish, salmon and tilapia.
Exsanguination is the loss of blood from the circulatory system of a vertebrate, usually leading to death. The word comes from the Latin 'sanguis', meaning blood, and the prefix 'ex-', meaning 'out of'.
In Judaism, shechita is ritual slaughtering of certain mammals and birds for food according to kashrut. One who practices this, a kosher butcher is called a shochet.
A captive bolt pistol is a device used for the stunning of animals prior to slaughter.
Pithing is a technique used to immobilize or kill an animal by inserting a needle or metal rod into its brain.
Stunning is the process of rendering animals immobile or unconscious, with or without killing the animal, when or immediately prior to slaughtering them for food.
The Humane Slaughter Act, or the Humane Methods of Livestock Slaughter Act, is a United States federal law designed to decrease suffering of livestock during slaughter. It was approved on August 27, 1958. The most notable of these requirements is the need to have an animal completely sedated and insensible to pain. This is to minimize the suffering to the point where the animal feels nothing at all, instead blacking out and never waking. This differs from animal to animal as size increases and decreases. Larger animals such as bovines require a stronger method than chickens, for example. Bovines require electronarcosis or something equally potent, though electronarcosis remains a standard. The bovine would have a device placed on their head that, once activated, sends an electric charge that efficiently and safely stuns them. Chickens, on the other hand, require much less current to be efficiently sedated and are given a run under electrically charged water. To ensure that these guidelines are met, the Food Safety and Inspection Service inspectors at slaughtering plants are responsible for overseeing compliance, and have the authority to stop slaughter lines and order plant employees to take corrective actions. Although more than 168 million chickens and around 9 billion broiler chickens are killed for food in the United States yearly, the Humane Slaughter Act specifically mentions only cattle, calves, horses, mules, sheep and swine.
Ikejime (活け締め) or ikijime (活き締め) is a method of killing fish that maintains the quality of its meat. The technique originated in Japan, but is now in widespread use. It involves the insertion of a spike quickly and directly into the hindbrain, usually located slightly behind and above the eye, thereby causing immediate brain death. After spiking the brain, a thin needle or piece of wire is inserted into the spinal column to prevent any further muscle movement. When spiked correctly, the fish fins flare and the fish relaxes, immediately ceasing all motion. Destroying the brain and the spinal cord of the fish will prevent reflex action from happening; such muscle movements would otherwise consume adenosine triphosphate (ATP) in the muscle, and as a result produce lactic acid and ammonia, making the fish sour, soggy and less tasteful. Furthermore, the blood contained in the fish flesh retracts to the gut cavity, which produces a better coloured and flavoured fillet, and prolongs shelf life. This method is considered to be the fastest and most humane method of killing fish. Ikejime-killed fish is sought-after by restaurants as it also allows the fish to develop more umami when aged.
In Islamic law, dhabihah, also spelled zabiha, is the prescribed method of slaughter for halal animals. It consists of a swift, deep incision to the throat with a very sharp knife, cutting the wind pipe, jugular veins and carotid arteries on both sides but leaving the spinal cord intact. The butcher is also required to call upon the name of Allah individually for each animal.
The legal aspects of ritual slaughter include the regulation of slaughterhouses, butchers, and religious personnel involved with traditional shechita (Jewish) and dhabiha (Islamic). Regulations also may extend to butchery products sold in accordance with kashrut and halal religious law. Governments regulate ritual slaughter, primarily through legislation and administrative law. In addition, compliance with oversight of ritual slaughter is monitored by governmental agencies and, on occasion, contested in litigation.
Animal slaughter is the killing of animals, usually referring to killing domestic livestock. It is estimated that each year, 80 billion land animals are slaughtered for food. Most animals are slaughtered for food; however, they may also be slaughtered for other reasons such as for harvesting of pelts, being diseased and unsuitable for consumption, or being surplus for maintaining a breeding stock. Slaughter typically involves some initial cutting, opening the major body cavities to remove the entrails and offal but usually leaving the carcass in one piece. Such dressing can be done by hunters in the field or in a slaughterhouse. Later, the carcass is usually butchered into smaller cuts.
Ritual slaughter is the practice of slaughtering livestock for meat in the context of a ritual. Ritual slaughter involves a prescribed practice of slaughtering an animal for food production purposes.
Fish fulfill several criteria proposed as indicating that non-human animals experience pain. These fulfilled criteria include a suitable nervous system and sensory receptors, opioid receptors and reduced responses to noxious stimuli when given analgesics and local anaesthetics, physiological changes to noxious stimuli, displaying protective motor reactions, exhibiting avoidance learning and making trade-offs between noxious stimulus avoidance and other motivational requirements.
Pain negatively affects the health and welfare of animals. "Pain" is defined by the International Association for the Study of Pain as "an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage." Only the animal experiencing the pain can know the pain's quality and intensity, and the degree of suffering. It is harder, if even possible, for an observer to know whether an emotional experience has occurred, especially if the sufferer cannot communicate. Therefore, this concept is often excluded in definitions of pain in animals, such as that provided by Zimmerman: "an aversive sensory experience caused by actual or potential injury that elicits protective motor and vegetative reactions, results in learned avoidance and may modify species-specific behaviour, including social behaviour." Nonhuman animals cannot report their feelings to language-using humans in the same manner as human communication, but observation of their behaviour provides a reasonable indication as to the extent of their pain. Just as with doctors and medics who sometimes share no common language with their patients, the indicators of pain can still be understood.
The Humane Slaughter Association (HSA) supports research, training, and development to improve the welfare of livestock during transport and slaughter. It provides technical information about handling and slaughter on its website, training for farmer staff and vets, advice to governments and industry, and funding of science and technology to make slaughter more humane. HSA is the sister charity to Universities Federation for Animal Welfare.
Japan has implemented several national animal welfare laws since 1973, but these protections are considered weak by international standards. Animal activism and protection laws in Japan primarily focus on the welfare of domesticated animals and farm animals.
Animal welfare and rights in South Korea is about the laws concerning and treatment of non-human animals in South Korea. South Korea's animal welfare laws are weak by international standards. There are a handful of animal welfare and rights organizations working in South Korea, which appear to be focused largely on the welfare of companion animals and the dog meat trade.
This article is about the treatment of and laws concerning non-human animals in Australia. Australia has moderate animal protections by international standards.
The Conservative Animal Welfare Foundation (CAWF) is an influential animal welfare organisation in the United Kingdom. According to The Daily Telegraph, "it is one of the most powerful lobbying groups in the Tory Party."
