Understanding Fish Welfare & Aquaculture
April, 2020

Article by Jennifer Kirsch

“The views I express here are mine alone and not necessarily a reflection of the organizations I work with.” – Jennifer Kirsch

Ever wondered how happy fish are? Don’t worry if you haven’t, until recently there was very little research into the topic, particularly considering fish’ ability to feel pain. It was Lynne Sneddon, a researcher at the University of Liverpool, who first showed that fish are capable of feeling pain in her 2002 paper. More research followed (see below) and by now, a significant amount of researchers are trying to find out how badly fish suffer. 
“Fish avoid painful stimuli by swimming away”
Photo by Jakub Kapusnak on Unsplash
Experiments have shown that fish avoid painful stimuli by swimming away (Chervova & Lapshin, 2011). In one experiment, fish were injected with a venom. When scientists dissolved painkillers in an unpreferred environment (a barren tank with no hiding opportunities), the fish still chose this tank over the one with rocks and dimmed light because the painkillers would ease their pain and that was their first priority (Sneddon, 2017). In another experiment, trout and zebrafish showed clear stress reactions when injected with a venom, both physiologically (e.g. cortisol levels) and behaviourally (e.g. rubbing affected body parts). These went away when those fish were given morphine (Sneddon, 2003). Their behavioural and physiological changes suggest that the painful stimuli evoke a reaction and thus they must perceive this pain. 
“There is as much evidence that fish feel pain and suffer as there is for birds and mammals – and more than there is for human neonates and preterm babies.” (Victoria Braithwaite)
Generally, there are three main sources of stress- namely chemical, physical, and perceived stress – that compromise fish welfare and elicit various responses in fish ranging from hormone level changes to decreased immune system functions and reduced overall health (Barton, 2002).
Chemical, physical and perceived stressors affect fish and lead to a cascade of responses that affect the individual’s welfare. Source: Barton, 2002
Every food choice begins with awareness.
Over the past few decades, the scientific consensus on fish, their needs and fears have been turned completely upside down and this has only been the starting point for a growing movement for fish welfare and rights. As always to make a change, you need the big guys, too. Luckily, governments and corporations have started to join the movement for better fish welfare. Eurogroup for Animals works to make sure fish welfare is considered in European institutions, and RSPCA was the first certification scheme to include welfare in their standards for salmon and trout. Other schemes are following this movement, for example ASC considers the inclusion of welfare indicators with their Fish Welfare Project, GAA and Friends of the Sea. Public concern is growing and charities, NGOs and nonprofits are revealing how bad fish’ conditions really are (see MFA & CIWF). Nevertheless, most focus seems to be on the sustainable growth of the aquaculture sector (see FAO – Blue Growth) while the welfare of the fish involved is still of little interest.
Photo by Lance Anderson on Unsplash
Aquaculture & Fisheries – problems & opportunities

How does it impact fish? 

Aquaculture operations are built on the premise that fish do not feel pain and the current production rate leaves little room for the ethical treatment of fish. To reduce costs, fish are only seldom stunned (=desensitized) before slaughter, kept in poor conditions (e.g. low water quality, starvation, overcrowding) and are frequently handled out of water (Ashley, 2007). This leads to disease outbreaks, injuries and aggression between individuals. As a result mortality rates on aquaculture farms are high, ranging from 25 to 50% from hatching until fish are grown (Undercurrentnews, 2018). Unfortunately, wild-caught fish cannot expect more humane treatment. With little oversight of fishing activities, many wild-caught fish are dying painfully. When being lifted with a net, lower-lying fish get crushed to death and remaining ones are left to suffocate onboard the ship. Animal Equality has recorded painful procedures for catching tuna which leaves them suffering for many hours while workers stab them.

How does aquaculture impact the ocean & environment? 

Ever seen a fish swim underneath your board while you were sitting in the line-up waiting for your next ride? You may be surprised to learn that even these wild fish are negatively affected by common aquaculture practice. Fish meal, which is used to feed carnivorous farmed fish (such as Atlantic salmon and rainbow trout), contributes a great deal to overfishing, depleting ocean fish stocks and causing problems along the whole food chain which threaten the well-being of our oceans (Naylor, 2005). In the last two decades, ⅓ of wild-caught fish worldwide has been used for fish meal production. This means 6-7 million metric tons per year (Banrie, 2012). In Mauritania, one of the major fish meal producing countries, up to 50% of wild-caught fish are used for fish meal production of which generally 5kg fish give 1kg of fish meal (Changing Markets Foundation, 2019).

Another problem with aquaculture is fish escaping from farms. Fish in farms are genetically and behaviourally unsuited for life in the wild, and these escapees interbreeding with wild individuals can lead to serious degradation of natural populations. Escaped fish can also turn into an invasive species, further disrupting local ecosystems and causing trophic cascades (McGraw, 2017). Escapees can also carry diseases that easily spread among wild populations. 

Disease spread is a major concern in mariculture (ocean-based aquaculture operations). Scientists are even concerned that fish on inland aquaculture farms could spread diseases to other animals, for example birds (Naylor, 2005). In mariculture, wild fish are attracted close to the cage where farmed fish are kept by feed. This is often enough for a pathogen (disease-causing organism) to spread from farmed to wild individuals and vice versa.

Finally, aquaculture produces wastewater which is released back into the environment. If this water does not get filtered, it contaminates local rivers and nature, eventually draining to the very ocean you dipped your head in this morning. Particularly in mariculture, where filtration is not possible because cages are in the ocean without any barriers, waste can easily diffuse (Gormaz, 2014).

Photo by Hanson Lu on Unsplash
The question of eating fish is a moral, ethical and environmental one.

Should I eat fish? 

Now here comes the million-dollar question: With fish feeling pain and aquaculture offering great potential for suffering, should we even continue eating fish? The answer to this question is a personal decision, though I would like to highlight some thoughts you may want to consider when making this decision: 

From an animal rights perspective, eating fish today is hard to defend ethically. Certification schemes are only doing first steps to include welfare standards and many fish suffer greatly, particularly in Asia where 90% of seafood consumed comes from (Bondando-Reantaso, 2005)

Fish from aquaculture is an arguably environmentally-friendly alternative to terrestrial meat, mainly in terms of greenhouse gas emissions, but this argument has to be taken with caution due to the various environmental impacts aquaculture operations can have apart from greenhouse gas emissions (Bland, 2017; Changing Markets Foundation, 2019). Unfortunately, fish are also not treated any better than farmed animals on-land.

“[T]he general agreement is that current aquaculture practices are neither meeting the needs of fish nor environment. Thus, the obvious environmental and animal welfare aspects of finfish aquaculture make it hard to ethically defend a fish diet.” (Bergqvist & Gunnarsson, 2011)

In the end, if you decide to continue eating fish, there are many small but impactful ways in which you can bring about change:

    • Push for change: Ask about welfare and environmental standards (e.g. through certifications) for the fish you buy or order in restaurants and shops.
    • Minimize: Try out some plant-based recipes and introduce meat-free days.
  • Eat responsibly: Many organizations offer seafood guides that focus on environmental impacts of species and aquaculture operations (Careful: These usually do not include welfare!)


Great news: The Good Food Institute is working on seafood substitutes which will soon offer an animal- and eco-friendly alternative to consuming seafood! If you want to show your support, the Good Food Institute is always accepting donations.

Further reads


Do fish feel pain?”, Victoria Braithwaite

What a fish knows?”, Jonathan Balcombe

Blog posts

Do fish feel pain?”, Fish Welfare Initiative

Pain of the fish”, La Fondation Droit Animal


Compassion in World Farming Fish Welfare

Aquatic Life Institute for top-down approach to this problem

Jennifer is an environmental scientist with a focus on marine conservation and a passion for the ocean. She has worked on various marine creatures, ranging from seals, over fish to whales and dolphins. Her bachelor thesis focused on the impacts of environmental change on northern elephant seal newborns which are expected to suffer greatly from human-induced climate change. She supports the Underwatercircle, a German organization focused on ocean, lake and river protection and aiming to inspire people for the ocean. In her free time, she loves to surf, swim and freedive.

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