Farming is broken: Let’s fix it. Part 3 - Animals

7 minute read — Published 22nd May, 2024

Factory Farming Causes Suffering on an Industrial Scale

Factory farming is a broken system: torturing animals, destroying the planet and putting our lives at risk.

Despite this, it remains the dominant system for producing meat, dairy, and eggs. In the USA, 99% of the meat we eat is factory farmed;¹ while in the UK roughly 73 - 85% of farmed animals live in factory farms.²

In this series, we explore the many harms of factory farming and some of the ways that we can, together, make farming kinder to people, the planet and animals.

In the first two articles, we explored the little-known impacts of factory farming on people and the planet. In this third article, we look at some of the ways that animals suffer in factory farms and what we can do about it.

Pigs: Smart and Loving, Yet Tormented

Pigs are amazing animals. They have individual personalities and a level of intelligence similar to dogs, making them some of the smartest animals alongside dolphins and elephants. They form strong bonds with humans, like Lulu the pet pig who saved her owner’s life.

Image courtesy of Shannon Johnstone / We Animals Media

In studies, we’ve found that pigs can use tools like sticks to dig and can even teach these skills to their piglets.³ Pigs recognize themselves in mirrors and use the reflections to solve puzzles.⁴

But there is overwhelming scientific consensus that pigs can feel pain, as well as more complicated emotions like fear.⁵ Chillingly, surveys of abattoir workers show that they agree,⁶ giving a horrifying insight into what life and death in the slaughterhouse must be like for workers and animals.

Pigs also suffer terribly in factory farms. Mother pigs are stuck in tiny crates where they can barely move, let alone care for their babies.⁷ To stop pigs from biting their own tails in crowded spaces, piglets have their tails cut off without any pain relief.⁸ Also, piglets are taken away from their mothers at just three weeks old, causing great distress for both⁹ With 1.5 billion pigs slaughtered each year, the scale of their suffering is immense.¹⁰

Chickens: Talkative and Clever, Yet Cramped and Mutilated

We often think of chickens as a bit simple, but they're far smarter and more complex than we think. They even have a devious side (as Mrs Tweedy will attest), roosters sometimes trick hens by pretending there’s food to get their attention.¹¹

Chickens are social birds with 20 different sounds to communicate, from greetings to warnings about predators.¹² They also form strong bonds with humans and with one another and can remember the faces of large numbers of their flock mates¹³ and even the faces of their owners¹⁴.

Despite their smarts, chickens suffer in factory farms. Their beaks are often cut to stop them from pecking each other in overcrowded spaces,¹⁵ which is very painful.¹⁶ Chickens raised for meat have been genetically manipulated to grow so fast their legs can’t support them, causing pain and fractures.¹⁷ Egg-laying hens are kept in cages so small they can’t even spread their wings.¹⁸ Male chicks, considered ‘useless’ by the egg industry because they don’t lay eggs and aren’t suitable for chicken-meat production, are killed as soon as possible, often blended alive in a high-speed grinder and then sold as fertilizer or food for other animals.¹⁹ Sadly, culling of male chicks occurs on factory farms and free range farms alike. These practices lead to suffering on an unimaginable scale, with 75 billion chickens slaughtered each year.²⁰

Cows: Playful and Friendly, Yet Mutilated and Exported

Cows love to play and chase each other,²¹ and some even play fetch with humans. They form close friendships and get anxious when separated.²² They groom each other to build and maintain these bonds, which helps them feel calm.²³

But in addition to being capable of complicated positive emotions, cows can also feel pain.²⁴ In factory farms, cows endure painful procedures like dehorning and castration without enough pain relief.²⁵ Dehorning involves using hot irons, causing severe burns. Male cows are castrated to make them more manageable and improve meat quality.²⁶ Additionally, cows are often shipped overseas in harsh conditions, facing extreme heat, starvation, and filth.²⁷ Cows are also capable of emotional distress, and on factory farms, where baby calves are separated from their mothers just hours after birth, the distress starts straight away.²⁸ Over 300 million cows are slaughtered for meat each year,²⁹ with another 260 million kept for dairy production.³⁰

Fish: Diverse and Social, Yet Suffocated and Diseased

Fish come in an incredible variety, with over 32,000 species.³¹ Many are social creatures, willing to endure electric shocks to stay close to their friends.³² Some fish even team up with other species to hunt, like groupers and moray eels working together.³³

Image courtesy of Ed Shephard / We Animals Media

Despite this, fish suffer³⁴ greatly in farms. They’re often killed by being left to suffocate in air or ice slurry, which is slow and painful.³⁵ Fish farmed in sea cages suffer from sea lice that eat their skin and eyes, causing many deaths.³⁶ Poor water quality in crowded ponds leaves fish struggling to breath, in constant stress and poor health.³⁷ About 124 billion fish are farmed and killed each year.³⁸

Shrimp: Colorful and Symbiotic, Yet Abused and Infected

Shrimp are fascinating creatures with at least 3,000 different species.³⁹ For example, pistol shrimp create a sound so loud by snapping their claws that the shockwave stuns their prey.⁴⁰ It is one of the loudest sounds in the ocean. Others, like alpheid shrimp, team up with goby fish for protection and food.⁴¹ Given these sophisticated behaviors, it’s unsurprising that they are capable of feeling pain as well.⁴²

The dynamic duo of goby and shrimp posing for a team photo. They should have told the goby to stop frowning! Photo source here.

In farms, shrimp endure cruel practices like the crushing or cutting off of their eyestalks, to make them mature faster so that they will reproduce earlier.⁴³ Crowded conditions and poor water quality cause suffocation, poisoning and diseases that kill up to 40% of farmed shrimp each year.⁴⁴

About 440 billion shrimp are farmed and slaughtered annually.⁴⁵

Farming is broken, let’s fix it

Factory farming inflicts unimaginable suffering on animals every year.Factory farming is so cruel because mega companies put profits above the suffering of animals and governments refuse to protect these animals from the kind of cruelty that would be illegal if the same animal was kept as a pet.

But we can change this.

Organizations in the USA and around the world, like The Humane League and Sinergia Animal, are putting pressure on corporations like grocery stores and restaurants to stop buying from producers using the worst practices (like the solitary confinement of sow stalls for pigs and battery cages for egg-laying hens).

Collectively these organizations have convinced more than 300+ US companies to phase out the cruelest farming practices for egg-laying hens and 140+ to phase out the worst practices for chickens raised for meat. These companies and brands include household names like Walmart. PepsiCo, KFC, Aldi, Walgreens, Burger King, Dunkin’, HelloFresh, Pizza Hut, Taco Bell, Kellog’s, CVS, Hershey, Oreo, and Unilever. This has cut the proportion of laying hens confined in cages in the US from 40% to almost 5% over the past decade.⁴⁶ Internationally, the Open Wing Alliance (a global network of organizations which they launched and still lead) has achieved 2400+ corporate commitments to better welfare in 70+ countries across six continents.

By supporting these organizations in their work, through volunteering, signing petitions and donating via FarmKind, we can make farming kinder for animals and start to put an end to this mass suffering industry.

Footnotes

1. Our World in Data (2023): “How many animals are factory-farmed” – "There is no specific definition of a ‘factory farm’. In agricultural research, they are often known as ‘concentrated animal feeding operations (CAFO)’. The US Department for Agriculture has consistent criteria for CAFOs to track and quantify these farms. ... the Sentience Institute has used publicly available data – in this case, published by the USDA Census of Agriculture (number of animals per farm) and Environment Protection Agency (CAFO definitions).. It estimates that 99% of livestock in the US were factory-farmed in 2017”.
Sentience Institute, 2019: US Factory Farming Estimates – "We estimate that 99% of US farmed animals are living in factory farms at present. By species, we estimate that 70.4% of cows, 98.3% of pigs, 99.8% of turkeys, 98.2% of chickens raised for eggs, and over 99.9% of chickens raised for meat are living in factory farms. Based on the confinement and living conditions of farmed fish, we estimate that virtually all US fish farms are suitably described as factory farms, though there is limited data on fish farm conditions and no standardized definition. Land animal figures use data from the USDA Census of Agriculture and EPA definitions of Concentrated Animal Feeding Operations.[↑] 2. Compassion in World Farming cites 73% in one estimate, and 85% in another:
(a) "It is estimated that around 73% of farmed animals in the UK are kept in indoor factory farms",
(b) “It’s a sad fact that around 85% of farmed animals are confined in factory farms here in the UK.” [↑] 3. Root-Bernstein et al. (2019): “Context-specific tool use by Sus cebifrons” – “Here, we report the first structured observations of unprompted instrumental object manipulation in a pig, the Visayan warty pig Sus cebifrons, which we argue qualifies as tool use. Three individuals were observed using bark or sticks to dig with.”, “Our observations suggest the hypothesis that the observed use of stick to dig with could have been socially learned through vertical transmission (mother-daughter).” [↑] 4. Broom et al. (2009): “Pigs learn what a mirror image represents and use it to obtain information” – “After 5 h spent with a mirror, the pigs were shown a familiar food bowl, visible in the mirror but hidden behind a solid barrier. Seven out of eight pigs found the food bowl in a mean of 23 s by going away from the mirror and around the barrier. Naïve pigs shown the same looked behind the mirror… To use information from a mirror and find a food bowl, each pig must have observed features of its surroundings, remembered these and its own actions, deduced relationships among observed and remembered features and acted accordingly.” [↑] 5. (a) Ison et al. (2016): "A Review of Pain Assessment in Pigs" – Review of 205 studies assessing the degree of pain experienced by pigs as part of farming practices
(b) Compassion in World Farming: Sentience in Pigs – 22-page report summarizing the research on pigs' capacity to suffer
(c) Rault et al. (2011): "Castration induced pain in pigs and other livestock" – Summary of studies showing pigs feel pain during castration [↑] 6. (a) Salazar et al. (2023): "Pigs' capacity to experience feelings and to suffer from tail lesion, ear lesion and lameness: Exploring citizens and pig farm and abattoir workers' knowledge and perceptions" – Survey participants (n=900) recruited in general public spaces and pig farms/abattoirs both "Agree" that pigs experience feelings (pain, fear, happiness, anxiety, and boredom)
(b) Peden et al. (2020): “Belief in pigs’ capacity to suffer: An assessment of pig farmers, veterinarians, students, and citizens” – “The results of the 194 responses provide evidence to suggest that the pig farmers did not ascribe their animals a diminished capacity to suffer. Rather, pig farmers expressed an enhanced belief in pigs’ capacity to experience hunger.” [↑] 7. See the Wikipedia entry for gestation crates, the standard practice that has only recently begun being phased out by some producers thanks to the advocacy of charities like those recommended by FarmKind [↑] 8. Nannoni et al. (2014): “Tail Docking in Pigs: A Review on its Short- And Long-Term Consequences and Effectiveness in Preventing Tail Biting” – “In spite of European legislation attempting to limit this practice, tail docking is nowadays the only preventive measure against tail biting which is widely adopted by farmers. Docking consists in amputating, usually without anaesthesia or analgesia, the distal part of the tail, in order to reduce its attractiveness and to sensitize it, increasing avoidance behaviour in the bitten pig. Tail docking results in both acute and chronic effects on pig welfare.” [↑] 9. Faccin et al. (2020): “Impact of increasing weaning age on pig performance and belly nosing prevalence in a commercial multisite production system” – “In nature, weaning in pigs is a gradual process that occurs around 10 to 12 wk of age, coinciding with the near complete maturation of the gastrointestinal tract. However, in commercial pig production, weaning is abrupt, occurring at around 2 to 4 wk of age. The stress suffered by weaned pigs in commercial conditions has been widely described in several studies.” [↑] 10. Our World In Data: Animal Welfare – 1.49 billion pigs slaughtered for meat globally in 2022 [↑] 11. Lori Marino (2017): “Thinking chickens: a review of cognition, emotion, and behavior in the domestic chicken” – “In addition to alarm calls, males also make food calls when they find a delectable tidbit. They combine these calls with rhythmic movements involving picking up and dropping the food morsel repeatedly—a signal called the tidbitting display”, “..hens use it to determine which males will provide food and, thus, with whom they want to mate”. “Deception is another example of possible Machiavellian Intelligence in chickens. Males will sometimes make a food call in the absence of any food. This serves to attract females who, once near them, can be engaged and defended against other males.” [↑] 12. ABC’s The Science Show: “Chris Evans – communication in chickens” [↑] 13. Lori Marino (2017): “Thinking chickens: a review of cognition, emotion, and behavior in the domestic chicken” – “Chickens, too, show notable abilities to recognize individuals in their social group, as well as the ability to keep track of the group’s social hierarchy and the individuals within it (as discussed previously). Not only do chickens recognize who is and is not a member of their social group, but they differentiate individuals within their own group. Under various experimental conditions, domestic chickens have demonstrated the capacity to visually discriminate and recognize a large number of conspecifics presented live.” [↑] 14. The millions of people who raise chickens as pets report that their chickens behave very differently when interacting with them versus other people, but the ability of chickens and their relatives to recognize and bond with humans has been established in some literature:
(a) Rubene and Løvlie (2021) on Junglefowl (a cousin of the domestic chicken): “Analyses of this behavior showed that red junglefowl chicks, during a foraging task, were more likely to approach a human experimenter, with whom they had undergone behavioral training, than they were to approach other objects, including another human.”
(b) Stephan et al. (2012) – “Pigeons are able to discriminate reliably between familiar and unfamiliar humans and provide evidence that facial features are important for this recognition.”
(c) Marzluff et al. (2012) – “Crows pay close attention to people and can remember specific faces for several years after a single encounter… These findings indicate that, similar to humans, crows use sophisticated visual sensory systems to recognize faces and modulate behavioral responses by integrating visual information with expectation and emotion.”

Meanwhile there is extensive evidence on the complex social relationships between chickens (e.g. Marino (2017): “Chickens are behaviorally sophisticated, discriminating among individuals, exhibiting Machiavellian-like social interactions, and learning socially in complex ways that are similar to humans.”) [↑] 15. See the Wikipedia entry for debeaking, a standard practice in the poultry industry to manage excessive pecking caused by confining chickens so tightly that they can’t establish a pecking order [↑] 16. Michael Gentle (2011): “Pain issues in poultry” – “Receptors which respond to noxious stimulation (nociceptors) have been identified and physiologically characterised in many different parts of the body of the chicken including the beak, mouth, nose, joint capsule and scaly skin.” The beak is mutilated to manage excessive pecking (see previous footnote). [↑] 17. Eurogroup for Animals (2023): “Why do fast-growing broiler chicken breeds need to be phased out?” – “95% of the broiler chickens currently reared on factory farms are fast-growing, selectively bred to reach slaughter weight in just five to six weeks. Their growth rate has a huge impact on their health and welfare”. “Lameness: the skeletal systems and leg muscles of fast-growing broiler birds cannot keep up with their rapid growth and weight gain. They therefore have muscles far too heavy for their fragile bones, leading to gait problems and considerable pain. Up to 58.8% of broiler chickens reportedly suffer from lameness.” “Lesions: due to their excessive weight, fast-growing broilers spend more time sitting than their slower-growing counterparts. It is common for them to develop lesions on their bodies that can become infected due to the poor hygiene standards in place on most factory farms.” “Heart failure: their unnatural growth rate puts immense pressure on the cardiovascular system, meaning countless birds die before slaughter.” [↑] 18. See the Wikipedia entry for battery cages, still the way the majority of eggs are farmed globally; however, FarmKind’s recommended charities have spared hundreds of millions of chickens from these systems. In particular, see the heading ‘cage size’. [↑] 19. See the Wikipedia entry for chick culling, whereby 7 billion healthy but unwanted animals are killed annually. [↑] 20. Our World In Data: Animal Welfare – 75.2 billion chickens slaughtered for meat globally in 2022 [↑] 21. Whalen et al. (2021): “Understanding Behavioural Development of Calves in Natural Settings to Inform Calf Management” – “Calves also engage in play behaviours... by head butting, mounting, jumping, and running; and often, these behaviours are integrated into extended play bouts.” [↑] 22. Krista McLennan (2013): “Social bonds in dairy cattle: the effect of dynamic group systems on welfare and productivity” – “Through the identification of preferential relationships using an association index, important social bonds between individuals were identified” … “In order to assess the strength of these positive relationships between dyads and to investigate the importance of these relationships to cattle, a short-term (30 minutes) separation test from the remainder of the herd was carried out. Cattle’s responses to the challenge were assessed both physiologically and behaviourally… significantly lower levels of behaviour suggestive of agitation (p<0.05) were observed when they were with their preferred partner compared to when they were with the nonpreferred partner. These results suggest that cattle were receiving social support from their preferred partners allowing them to have a reduced stress response to the social isolation test.“ [↑] 23. Freslon et al. (2020): “Understanding Allogrooming Through a Dynamic Social Network Approach: An Example in a Group of Dairy Cows” – “Inter-individual bonds and preferential relationships are mainly established, maintained, and reinforced through allogrooming. This behavior also enhances group cohesion and maintains social stability, reduces social tension and has calming effects” [↑] 24. Steagall et al. (2021): “Pain Management in Farm Animals: Focus on Cattle, Sheep and Pigs” – “Mammals generally have similar nociception across different species, and it is safe to assume that events that are painful in humans are experienced similarly in other mammals”. “As observed during dehorning, hot-iron disbudding produces severe pain for hours as evidenced by severe burns and large open wounds, changes in behavior (e.g., vocalization, kicking and falling), decreases in mechanical nociceptive thresholds, and increases in serum cortisol levels…. Pain-induced behaviors in calves after dehorning include head shaking, ear flicking, head rub against surfaces and objects, frequent changes in position, increased time lying, and vocalization up to 72 h after the procedure. The use of local anesthetics and NSAIDs before dehorning will blunt these responses” [↑] 25. (a) Cows grow horns unless they have the hornless (or “polled”) gene. This gene is rare, for example <1% of dairy cows in the EU have it. However selective breeding is increasing the prevalence of naturally hornless cows, especially among those raised for beef (for example in Canada the majority of herds are >75% naturally hornless).
(b) Horn removal is standard industry practice, with 94% of US dairy farmers dehorning cattle according to the USDA’s 2014 Dairy Report, and 81.5% of cows being dehorned in the EU in 2010. The rates for beef cows is much lower, for example 36% in the EU in 2010.
(c) Dehorning is painful, with Steagall et al. (2021): “Pain Management in Farm Animals: Focus on Cattle, Sheep and Pigs” noting “hot-iron disbudding produces severe pain for hours as evidenced by severe burns and large open wounds, changes in behavior (e.g., vocalization, kicking and falling), decreases in mechanical nociceptive thresholds, and increases in serum cortisol levels… Pain-induced behaviors in calves after dehorning include head shaking, ear flicking, head rub against surfaces and objects, frequent changes in position, increased time lying, and vocalization up to 72 h after the procedure”
(d) The use of pain relief during and after the process is uncommon, with Gottardo et al. 2011 finding that only 10% of surveyed European farmers used local anesthesia during the process and only 5% providing pain relief afterwards, while Canadian industry surveys suggest just 27-31% of producers provide pain relief. [↑] 26. (a) Castration is standard practice, with 91% of large beef operations in the US castrate their calves, according to the 2017 USDA National Animal Health Monitoring Beef Cow-Calf Study, while Coetzee et al. (2010)’s survey of US farmers and veterinarians found that 95% of respondents castrate light-weight calves
(b) Castration is painful, with Steagall et al. (2021): “Pain Management in Farm Animals: Focus on Cattle, Sheep and Pigs” notes that “all methods of castration at any age in any species are painful”
(c) The use of pain relief is rare, with Coetzee et al. (2010) recording that 20% of US survey respondents provide it, and Fajt et al. (2011) recording 30%. Even when it’s used, Steagall et al. (2021) only finds “some evidence of partial efficacy for analgesia following castration by band or surgical means in beef cattle”. [↑] 27. (a) Heat stress: Caulfield et al. (2014): “Heat stress: A major contributor to poor animal welfare associated with long-haul live export voyages” – The paper describes how the combination of hot weather and high stocking density on cattle ships (such that heat can’t dissipate effectively) leads to high temperatures. They describe experimental and real world measurements of this phenomena, with cows’ core body temperatures reaching as high as 109°F (43°C ). See news coverage of heat stress incidents for livestock during live export here and here.
(b) Starvation: Numerous incidents have been documented in which livestock on export boats have been found starving, in some cases due to delays in shipping (e.g. here, here and here).
(c) Severe buildup of feces: For example, photos from an independent observer’s report produced for the Australian government of the Gulf Livestock 1 cargo ship show cows confined to a pen for the duration of the trip covered in their own accumulating feces by the 8th day. Meanwhile, in 2024, a strong stench in parts of Cape Town led to an investigation that traced the source to a cargo ship docked at the port. Authorities discovered cows on board the ship confined with 2.5 weeks' worth of accumulated manure.
(d) Frequent death: Livestock dying is the ‘tip of the iceberg’ of suffering during live export, as only especially extreme horrible conditions will lead to death. Despite this, it appears that livestock die in large numbers during export. In Australia, one of the few countries keeping track of this phenomenon, over 19,000 livestock died during export between 2018-2023, Meanwhile, numerous mass mortality events have been reported in the media, including in some of the articles linked for items (a) - (c). [↑] 28. (a) Dairy cows are separated from mothers within hours: Budzynska & Weary (2008): “Weaning distress in dairy calves: Effects of alternative weaning procedures” – “Dairy calves are typically separated from the cow within hours of birth but continue to be fed milk artificially for several weeks.”
(b) Weaning naturally occurs are 7-14 months: Whalin et al. (2021): “Understanding Behavioural Development of Calves in Natural Settings to Inform Calf Management” – “Different from natural settings, where weaning from the mother is a gradual process (culminating when the calf is 7 to 14 mo old)… dairy calves are usually weaned abruptly, with milk feeding stopped by 9 wk of age”. [Note that while milk feeding lasts for 9 weeks, separation from the mother happens within hours, with milk fed artificially after this]. “Abrupt weaning may cause challenges such as depressed growth and increased distress behaviours such as walking and vocalizations, compared to calves that are gradually weaned”. [↑] 29. Our World In Data: Animal Welfare – 308.6 million cows slaughtered for meat globally in 2022 [↑] 30. (a) WWF states “there are approximately 270 million dairy cows in the world”
(b) Compassion in World Farming uses data from the Food and Agriculture Organization of the United Nations from 2012 to arrive at an estimate of over 264 million dairy cows [↑] 31. Joseph Nelson (2016): “Fishes of the World: Taxonomic Diversity” [↑] 32. Millsopp & Laming (2008): “Trade-offs between feeding and shock avoidance in goldfish ( Carassius auratus)” – ‘goldfish will endure more electric shocks to remain in proximity to a companion than to obtain food, indicating that the motivation to remain with a companion is stronger than the motivation to avoid electric shock” [↑] 33. Bshary et al. (2006): “Interspecific Communicative and Coordinated Hunting between Groupers and Giant Moray Eels in the Red Sea” – “A coordinated hunt between individuals of the two species confronts prey with a multipredator attack that is difficult to avoid… Groupers actively visit moray eels at their resting places and make use of visual signals to engage morays in a joint hunt… In addition to signalling before any hunting events, groupers also recruited moray eels after unsuccessful hunts. Typically, a hunt ended unsuccessfully because prey escaped into a crevice that was inaccessible to the grouper… In a few cases, however, the groupers (n = 9 individuals, total observation = 14) swam to a giant moray eel that was within 15 m of the prey's hiding place, signalled to the moray, and apparently tried to guide it to the prey's location. Finally, six groupers (total n = 21) were observed to remain directly above the crevice where prey were hiding and engage in wide head shakes, while simultaneously performing a head stand…Headstand shakes invariably attracted other predators to the prey's location in the crevice”. You can see a video of this behaviour here. [↑] 34. (a) Fish have pain receptors:
(i) Dunlop and Laming (2005): “Mechanoreceptive and nociceptive responses in the central nervous system of goldfish (Carassius auratus) and trout (Oncorhynchus mykiss)” – “This study has shown that there is neuronal activity in all brain areas including the telencephalon, suggesting a nociceptive pathway from the periphery to the higher central nervous system of fish”
(ii) Sneddon et al (2003): “Do fishes have nociceptors? Evidence for the evolution of a vertebrate sensory system” – “This study provides significant evidence of nociception in teleost fishes and furthermore demonstrates that behaviour and physiology are affected over a prolonged period of time, suggesting discomfort.”
b) Distress behavior when in pain, and the effectiveness of painkillers L. Sneddon (2019): “Evolution of nociception and pain: evidence from fish models” – “Potentially painful events result in behavioural and physiological changes such as reduced activity, guarding behaviour, suspension of normal behaviour, increased ventilation rate and abnormal behaviours which are all prevented by the use of pain-relieving drugs”.
(c) Making trade-offs to access pain relief: L. Sneddon (2015): “Pain in aquatic animals” – “However, will fish pay a cost to accessing analgesia? If the internal experience of pain is aversive then they should sacrifice either effort or access to a resource or favourable area to obtain pain relief… Zebrafish seek to reduce their pain by forgoing the opportunity to be in a preferred area and spending time in a non-preferred chamber to access analgesia” [↑] 35. (a) Inhumane: Slaughter by asphyxiation is considered inhumane by the World Organization for Animal Health and the Aquaculture Stewardship Council who says it’s “proven to be highly aversive to fish”. Poli, et al. (2005) suggests it causes cortisol (stress hormone) levels to increase 8-fold.
(b) Slow: Poli, et al. (2005) suggests that death by asphyxiation often takes over an hour
(c) Stunning is recommended: The growing consensus is that fish need to be stunned before slaughter to avoid unacceptable suffering. For example, the World Organization for Animal Health says “as a general principle, farmed fish should be stunned before killing, and the stunning method should ensure immediate and irreversible loss of consciousness”, and the Humane Slaughter Association says “the key principle of humane killing is to render the fish immediately unconscious and insensible to pain” [↑] 36. (a) Sea lice being a common issue: Sea lice are common enough that the Scottish Government has a policy for their management on salmon farms. “Infection with L. salmonis”, a species of sea lice, “is one of the most important health issues for the Scottish salmon aquaculture industry”.
(b) Sea lice infestations cause death: Knut Wiik Vollset (2019): “Parasite induced mortality is context dependent in Atlantic salmon: insights from an individual-based model” – “The current Norwegian risk evaluation of sea lice on salmon uses a mortality rate based on lice per gram salmon smolt, which corresponds to a mortality of 0% if there are <2 lice per fish, 20% if 2–4 lice, 50% if 4–5 and 100% if >6 lice for a 20 gram salmon smolt” [↑] 37. (a) Importance of water quality for welfare: Animal Charity Evaluators (2020): “Farmed fish welfare report” – “Water quality seems to be widely regarded as one of the most—if not the most—important factors for farmed fish welfare… Water quality refers to a variety of measurements rather than a single specific welfare indicator. These include dissolved oxygen (DO) levels, temperature, pH levels, ammonium levels, and more… DO seems to be one of the most, if not the most, important indicator for water quality”.
(b) Impact of poor water quality on welfare: Eurogroup for Animals (2022): “On-farm Welfare Standards in Aquaculture” – “Poor water quality elicits a stress response in fish. Fish are able to tolerate poor conditions for a short period only. When the conditions become too challenging or prolonged, fish experience chronic stress which can impair immune function, growth and reproductive function. Furthermore, chemical substances may have toxic effects at the level of cell and tissue but, in addition, elicit an integrated stress response.”
(c) Prevalence of water quality issues: Fish Welfare Initiative and Shrimp Welfare Project have closely observed standard onshore fish farming practices in India, Vietnam, and the Philippines which collectively farm billions of fish each year. They note that stocking density is typically extremely high, with little or no removal of fish faeces from the ponds, which accumulates and pollutes the water with toxic ammonia, low dissolved oxygen, and excessive organic material. Poor water quality appears to be the default, rather than the exception, in these systems. [↑] 38. Mood et al. (2023): “Estimating global numbers of farmed fishes killed for food annually from 1990 to 2019” – “Farmed finfish numbers killed annually for food have increased nine-fold, to 124 billion (1.24 × 10^11, range 78–171 billion) in 2019” [↑] 39. (a) Controversy on what counts: The Palaeos Encyclopedaea’s entry for ‘Decapoda: Reptantia’ – “Unlike the mammals, where a quite stable consensus has emerged, with the decapods every study gives totally different results. Nor do even one of these studies match any of the rival morphology studies.”
(b) Consensus on the lower bound on number of species: De Grave and Fransen (2011) – “At a higher level in decapod classification it has long been recognised that three distinct lineages of shrimps can be distinguished: Dendrobranchiata, Stenopodidea and Caridea, a system which has not been seriously challenged by recent studies… Working from a preliminary version of the present catalogue estimated the species/subspecies richness of shrimps as follows: Dendrobranchiata (505), Stenopodidea (58) and Caridea (circa 3108)” [↑] 40. BBC Wildlife - Weird Nature – Pistol Shrimp sonic weapon – “By snapping its claws it can not only make communication sounds, but something far deadlier… It deals a knock-out blow from a distance by using its claw as a sonic weapon.” [↑] 41. (a) Num and Rhee (2020): “Complete mitochondrial genome of the yellow prawn-goby” – “It has a fascinating habitat that shares a burrow with alpheid shrimps as mutualistic symbiosis”
(b) Tropical Fish Magazine: “Pistol Shrimps and Gobies: Perfect Partners” – “The goby benefits from the shrimp's digging and construction skills, having access to a well-built burrow. Pistol shrimps have poor eyesight, and they use gobies as an early warning system to detect predators” [↑] 42. (a) The scientific consensus is that shrimp can feel pain:
(i) EU European Food Safety Authority (2005): “Corrigenda to the Scientific Opinion on ‘Aspects of the biology and welfare of animals used for experimental and other scientific purposes’” – Regarding ‘Category 1’ which contains shrimp: “The scientific evidence clearly indicates that those groups of animals are able to experience pain and distress”. Regarding decapods, which include shrimp: “The largest of these animals are complex in behaviour and appear to have some degree of awareness. They have a pain system and considerable learning ability. Little evidence is available for many decapods, especially small species. However, where sub-groups of the decapods, such as the prawns, have large species which have been studied in detail they seem to have a similar level of complexity to those described for crabs and lobsters.”
(ii) London School of Economics and Political Science (2021): "Review of the Evidence of Sentience in Cephalopod Molluscs and Decapod Crustaceans" – “We recommend that all cephalopod molluscs and decapod crustaceans be regarded as sentient”
(b) Their sentience is enshrined in legislation in various countries:
(i) United Kingdom: UK Animals Welfare (Sentience) Act (2022) – The Act recognises the sentience of decapod crustaceans, which includes shrimps.
(ii) Switzerland: Animal Welfare Ordinance Act (2008) – The Act requires provisions for decapods (including shrimp) such as stunning before slaughter and adequate water quality on farms.
(iii) Norway: Norwegian Animal Welfare Act (2010) – The Act protects decapods (including shrimp) through regulations on killing, confinement and transport.
(iv) Austria: Austrian Animal Welfare Act (2004) – The Act specifies acceptable water quality ranges (e.g. dissolved oxygen levels) for decapods, which includes shrimps. [↑] 43. (a) Historic use of eyestalk ablation:
(i) Saint-Hernandez et al. (2008): “Effect of unilateral and bilateral eyestalk ablation in Litopenaeus vannamei male and female on several metabolic and immunologic variables” –“Eyestalk ablation (EA) has been used since 1970 to improve the aquaculture production of Penaeus spp. larvae”, “Eyestalk ablation is the most common procedure to induce gonadic maturation in commercial hatcheries of penaeid shrimp”.
(ii) Uawisetwathana et al. (2011): “Insights into Eyestalk Ablation Mechanism to Induce Ovarian Maturation in the Black Tiger Shrimp” – “Eyestalk ablation is commonly practiced in crustacean to induce ovarian maturation in captivity”
(b) Continued use of eyestalk ablation Rethink Priorities (2023): “Welfare considerations for farmed shrimp” – “However, farmers often still ablate breeders, even when conditions are adequate for quick maturity” [↑] 44. (a) Disease is rampant:
(i) Asche et al. (2021): The economics of shrimp disease: “Although diseases are a major concern for most aquaculture species, shrimp may be the successful aquaculture species whose production has been most impacted by diseases.”
(ii) Babu et al. (2021): “Surveillance of disease incidence in shrimp farms located in the east coastal region of India and in vitro antibacterial efficacy of probiotics against Vibrio parahaemolyticus” – “Results confirmed infection with Enterocytozoon hepatopenaei (32.4%), Vibrio parahaemolyticus (27.7%), White Spot Syndrome Virus (25.4%), Vibrio alginolyticus (16.1%), Vibrio harveyi (13.1%), Monodon-type baculovirus (4.61%), and infectious Hematopoietic Necrosis Virus (2.3%) in the collected shrimps”
(iii) Lee et al. (2022): “Viral Shrimp Diseases Listed by the OIE: A Review” – “The expansion of shrimp aquaculture has also been accompanied by various disease outbreaks, leading to large losses in shrimp production”, “To find a fundamental solution, various studies on the etiology of these diseases are needed, and breeding organism-friendly aquaculture methods will be required, which consider animal welfare, such as maintaining an appropriate breeding density and a clean breeding environment, using SPF (specific pathogen free) or SPR (specific pathogen resistance), and nature-friendly breeding and nurturing for a disease-free and sustainable shrimp farming industry”
(b) Disease causes high mortality:
(i) Losses as high as 40% of global production: Walker and Mohan (2009): “Viral disease emergence in shrimp aquaculture: origins, impact and the effectiveness of health management strategies” – “It was estimated in 1996 that annual disease‐related losses in shrimp farming globally were ∼US$3000 million or 40% of the total production capacity of the industry (Israngkura & Sae‐Hae 2002)”
(ii) Losses of 80-100% in specific outbreaks: Walker and Mohan (2009) – “White spot syndrome virus (WSSV) is by far the most devastating pathogen of farmed shrimp. It infects all cultured penaeids and has been responsible for much of the economic impact of disease on production globally… White spot disease commonly results in 80–100% mortality within 5–10 days of the first appearance of clinical signs (Chou et al. 1995)”
(c) Poor water quality is a major issue
(i) Poor water quality is common: Our recommended charity, Shrimp Welfare Project, has found dirty water with low dissolved oxygen to be the norm in the farms they have visited.
(ii) Poor water quality is detrimental to welfare: Wiyoto et al., 2016: “Water Quality and Sediment Profile in Shrimp Culture” – “Water parameters… are known to directly affect the shrimp welfare (e.g. oxygen, ammonia, nitrite and H2S)”.
(iii) Poor water quality can lead to death by suffocation or poisoning in extreme cases: Allan and Maguire (1991): “Lethal levels of low dissolved oxygen and effects of short-term oxygen stress on subsequent growth of juvenile Penaeus monodon” [↑] 45. Rethink Priorities (2020): “Numbers of wild-caught shrimp and other animals annually slaughtered” – “As shown, the number of farmed shrimp killed in a year (440 billion) exceeds several times the figure of the most numerous vertebrate species used in the food system–namely, fishes and chickens” [↑] 46. We can’t give 100% of the credit for this progress to THL but they played a pivotal role in it [↑]