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We now know that fish are cognitively more competent than we thought before [with] some species having very sophisticated forms of cognition… There is as much evidence that fish feel pain and suffer as there is for birds and mammals – and more than for human neonates and preterm babies.

Victoria Braithwaite, Do Fish Feel Pain? (2010)1

Animal welfare

salmon leaping up waterfall

Animals, including fish, are sentient beings and deserve a good quality of life and humane death. Animal welfare is not just about the absence of suffering, but about the provision of ‘what animals want and need’ so that they can lead healthy, happy lives. An animal is considered to have good welfare when he/she is in good physical condition, has a strong mental state (for instance: confident, not fearful or in pain) and is able to express important behaviours (such as foraging; dustbathing; making a nest; or socialising).

Good animal welfare is underpinned by good feeding, housing / environment, health, breeding, and critically good stockmanship / management (animal care).

How we treat animals is our ethical and moral imperative; how they perceive their lives is their welfare state.

Introduction to the problem and scale

  • Merging all aquaculture production (fish and other aquatic animal species), global production was 82.1 million tonnes in 2018. China alone produces about 40 million tonnes per year and Asia (excluding China) produces about 20 million tonnes2
  • Fish aquaculture has been growing by an average 5.7% per year since 20003. Surveys by the Global Aquaculture Alliance showed that aquaculture fish production increased by 73% between 2010-20193.
  • In 2017, global farmed fish production was 53.4 million tonnes, accounting for almost half (47.7%) of all aquaculture production with a value of US$ 139.7 billion4. This has been estimated to include 51-167 billion fish5.
  • Fish farming activities can have negative effects on biodiversity by releasing polluting effluents, consuming wild fish for feed, transmitting disease to wild stocks and releasing invasive escaped fish6.
  • The majority of fish farming is intensive, with fish kept in barren environments at high stocking densities to maximise profit and farm productivity. They experience a high risk of injuries, diseases, and parasite infections, and are limited in their ability to express natural behaviours. Subsequently, their welfare is often deemed to be poor.
  • There is evidence that fish are sentient and feel pain7,8 and, as such, deserve a good quality of life. As seen below, this is also the shared opinion of the majority of people/consumers in different regions of the world.
    • Findings from an EU survey: “the majority of EU citizens agree that fish are sentient being (65%), and that they feel both positive (55%) and negative emotions (65%), and that not allowing fish to exhibit natural behaviours has a negative impact on their welfare”9
    • South America: a survey of people with higher education showed that 71.8% of participants in Brazil perceived fish as sentient and 79.7% participants in Colombia10.
  • The World Organization for Animal Health (OIE) Aquatic Animal Code, has published recommendations on the welfare of farmed fish during transport, stunning and slaughter11. In the EU, these guidelines are used as a measure of compliance with EU legislation, but they are rarely followed around the rest of the world.
    • In many countries, fish are not included in animal welfare and humane slaughter legislation.
    • Fish welfare is considered in some certification schemes (e.g. RSPCA and Soil Association), however, many fish-specific schemes focus largely on sustainability issues and omit key welfare issues12.
    • Fish welfare is, however, being increasingly considered by companies throughout the supply chain in their corporate animal welfare policies (as demonstrated in the Business Benchmark for Farm Animal Welfare (BBFAW) (
    • South America: In the same survey mentioned above, 72% of participants in Brazil and 76% of participants in Colombia believed that fish should be included in humane slaughter regulations10.
  • Although farmed fish tend to have a low food conversion ratio (FCR) (1-2.4), only 14-28% of the protein and 6-25% of the calories used in fish feed is turned into human edible fish13. Moreover, it takes 3 - 4 tonnes of raw fish to make one tonne of fishmeal and fish oil for fish feed14.

Link to intensive fish farming

  • As of 2016, there were 369 recorded species of farmed finfish15. However, the most farmed species is carp, which accounts for 61% of total farmed fish production16. Each species of farmed fish has its own characteristics and requirements for maintaining positive welfare.
  • In intensive systems, fish are farmed in nets, ponds, or cages, inland or offshore, and are kept at such a high stocking density that they are unable to obtain sufficient feed from their environment. As well as high stocking densities, intensive fish farms are often characterised by barren environments, high levels of disease and parasites, and poor water quality.

What are the welfare issues?

farmed salmon suffering with lice infestation
  • Confinement: The high stocking densities of fish within a net, pond or cage results in physical injuries such as fin damage from aggressive conspecifics and poor body condition resulting from food competition and stress. High stocking densities can also cause poor water quality and increased risk of disease and parasite infections17. Fish should be provided with the opportunity to express natural behaviours and access favourable environmental conditions, which is not possible at high stocking densities.
  • Disease and parasites: Diseases and parasites can spread through the water from one farm to another because of the close proximity between them in many areas18,  and they can also spread to wild fish19.
    • In farmed salmon, sea lice are a widespread problem. Sea lice cause open wounds and injuries to the gills and mouth, and they can result in the infected fish dying. Most sea lice treatments can also cause injury and death for the fish. As the salmon farming industry expands, the number of salmon infected with sea lice is likely to increase.
  • Transport: Fish are transported as juveniles to on-growing facilities (e.g. to sea cages) or from rearing pens to slaughter facilities. Common methods include transport via well boat (boats with a well in which to keep fish alive), by towing of cages with tugs (where the fish must swim to keep up with the speed of the boat), or by road20, 21. Capture, loading, transport, and unloading of the fish for transport, as well as high stocking densities and poor water quality during transport, can cause exhaustion, physical injury, and severe physiological stress22. There are currently no maximum transport times written into legislation for fish and transport is not considered by most certification schemes.
  • Inhumane slaughter: Fish are slaughtered without stunning in many areas. This causes prolonged suffering as death can be slow to occur depending on the killing methods used. This means that millions of fish suffer unnecessarily every year22. Inhumane slaughter methods (without stunning) involve cutting the gills to sever the blood vessels so that fish remain conscious while they bleed out. Carbon dioxide is also still used to slaughter fish in some countries, a process during which the fish exhibits head shaking and vigorous tail shaking for up to two minutes before losing consciousness23. Exposure to air results in fish taking over an hour to lose consciousness, depending on the species24. Live chilling in ice slurry without an effective stun, traditionally used for bass and bream, can result in the fish struggling for up to 40 minutes25 and it can take over 3 hours for the fish to die24. This means that fish slaughtered using air or live chilling may be gutted alive.
  • Fasting: Prior to transport or slaughter, fish are fasted to reduce oxygen demand and physical activity and to empty the digestive system to reduce water fouling. In salmonids, for example, 2-3 days is a sufficient fasting period to reduce metabolic rate11. Some certification schemes, even allow farms to withhold food for up to two weeks26.
  • Crowding: In addition to fasting, fish are crowded prior to slaughter at extremely high stocking densities while they wait to be pumped or netted out to be killed. This is a stressful procedure that can lead to reduced water quality and physical injuries from the net or other fish. Fish will often be seen gasping for air, attempting to escape (jumping), and burrowing into the net.
  • Physical health: In fish farming, mortality rates during rearing that are considered acceptable by the industry can be high (up to 20% in pangasius27). In addition, culls to prevent the spreading of disease28 or mass mortality events29 occur during which tens of thousands of fish die. High stocking densities during rearing and crowding events also cause physical injuries such as fin damage, skeletal deformities, snout, and eye damage, and skin/scale damage. Physical health is also impaired as a result of disease and parasites.

What are the environmental and sustainability issues?

  • Damage to the natural environment:
    • By weight, almost a fifth of the world’s total catch of wild fish is processed into Fishmeal and Fish Oil (FMFO), of which 69% of fishmeal and 75% of fish-oil production are used to feed farmed fish30. This accounts to 0.5-1 trillion fish being processed into fish feed every year31.
    • Aquaculture can cause environmental pollution and habitat/wildlife destruction because of an excess of nutrients (faeces and uneaten food) and chemical runoff from treatments entering the surrounding area32, 32.
    • Approximately 84% of farmed fish are freshwater fish2 which can put a strain on limited water resources18.
  • Damage to wild animals:
    • Escaped farmed fish can be a threat to wild fish populations. Fish farmed in the proximity of wild populations can sully the genetic diversity of wild fish populations and transfer pathogens from farmed fish to wild populations18. Escaped fish farmed in non-native areas can replace endemic species18.

Link to the relevant Sustainable Development Goal (SDG)

  • SDG 14: Life below water. Conserve and sustainably use the oceans, seas, and marine resources for sustainable development34
  1. Braithwaite, V. (2010). Do Fish Feel Pain? Oxford University Press. Oxford.
  2. Food and Agriculture Organisation of the United Nations (FAO). (2020). The state of World Fisheries and Aquaculture - Sustainability in Action (in brief)
  3. GAA. (2019). GOAL 2019: Global finfish production review and forecast.
  4. Tacon, A.G.J. (2020). Trends in Global Aquaculture and Aquafeed Production: 2000–2017. Rev. Fish. Sci. Aquac, 28(1), 43–56.
  5. Mood, A., Brooke, P. (2019). Fishcount: Estimated numbers of individuals in global aquaculture production (FAO) of fish species (2017).
  6. Diana, J.S. (2009). Aquaculture Production and Biodiversity Conservation, BioScience, 59(1), 27–38
  7. Compassion in World Farming. (2019). Why fish welfare matters: the evidence for fish sentience.
  8. Mood, A., Brooke, P. (2019). Fishcount: fish are sentient.
  9. Eurogroup for animals. (2018). EU citizens and leading fish stakeholders demand better welfare for fish.
  10. Rucinque, D.S., Souza, A.P.O., Molento, C.F.M. (2017). Perception of Fish Sentience, Welfare and Humane Slaughter by Highly Educated Citizens of Bogotá, Colombia and Curitiba, Brazil. PlosOne 12(1).
  11. World Organization for Animal Health. (2008). Aquatic code.
  12. Compassion in World Farming. (2020). Fish certification schemes.
  13. Fry, J.P., Mailloux, N.A., Love, D.C., Milli, M.C., Cao, L. (2018). Feed conversion efficiency in aquaculture: do we measure it correctly? Environ. Res. Lett, 13(2), 024017.
  14. IFFO, International Fishmeal, and Fish Oil Organisation. (2010). IFFO, International Fishmeal, and Fish Oil Organisation.
  15. Food and Agriculture Organization of the United Nations. (2018) The State of World Fisheries and Aquaculture 2018–Meeting the sustainable development goals.
  16. Fishcount. (2019). Development of intensive fish farming.
  17. World Fish Center. (n.d). Fish disease under the microscope.
  18. Jennings, S., Stentiford, G.D., Leocadio, A.M., Jeffery, K.R., Metcalfe, J.D., Katsiadaki, I., Auchterlonie, N.A., Mangi, S.C., Pinnegar, J.K., Ellis, T., Peeler, E.J. (2016). Aquatic food security: insights into challenges and solutions from an analysis of interactions between fisheries, aquaculture, food safety, human health, fish and human welfare, economy, and environment. Fish and Fisheries, 17(4), 893-938.
  19. Johansen, L.H., Jensen, I., Mikkelsen, H., Bjørn, P.A., Jansen, P.A., Bergh, Ø. (2011). Disease interaction and pathogens exchange between wild and farmed fish populations with special reference to Norway. Aquaculture, 315(3-4), 167-186.
  20. EFSA. (2004). Opinion of the Scientific Panel on Animal Health and Welfare on a request from the Commission related to the welfare of animals during transport. The EFSA Journal, 44, 1-36.
  21. European Commission. (2016). Welfare of farmed fish: Common practices during transport and at slaughter
  22. Lines J.A., Spence J. (2014). Humane harvesting and slaughter of farmed fish.
  23. Robb, D.H., Wotton, S.B., McKinstry, J.L., Sørensen, N.K., Kestin, S.C., (2000) Commercial slaughter methods used on Atlantic salmon: determination of the onset of brain failure by electroencephalography. Vet Rec, 147(11), 298-303.
  24. Bergqvist, J., Gunnarsson, S. (2013). Finfish Aquaculture: Animal Welfare, the Environment, and Ethical Implications. J Agric Environ Ethics, 26(1), 75-99.
  25. Huidobro, A., Mendes, R., Nunes, M.L. (2001). Slaughtering of gilthead seabream (sparus aurata) in liquid ice: Influence on fish quality. Eur Food Res Technol, 213(4-5), 267-272.
  26. Naturland. (2020).
  27. ASC Pangasius Standard. (2019).
  28. Evans O. (2018). Fish farmer culls 800,000 juvenile salmon in Washington.
  29. Scottish government. (2020). Fish Health Inspectorate: mortality information.
  30. FAO. (n.d.). Main ethical issues in fisheries.
  31. Mood, A., Brooke, P. (2019). Fishcount: Fish caught for reduction to fish oil and fishmeal.
  32. NOAA. (n.d). Nutrient impacts of Finfish aquaculture.
  33. FAO. (n.d). Environmental aspects of aquaculture in the tropics and sub-tropics.
  34. United Nations Department of Economic Social Affairs Sustainable Development

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