Fascinated by Fish – why their welfare matters

Perhaps the most farmed group of species on the planet is fish, yet the welfare of these waterborne animals is all too often overlooked.

Here at Compassion, we are gearing up our work on fish welfare to tackle what we see as the burgeoning factory farm industry under the water. I was delighted therefore to interview Dr Lynne Sneddon, Director of Bioveterinary Science at the University of Liverpool, on her groundbreaking work relating to the welfare of fish.

Dr Sneddon’s work focuses on reducing stress and ill health in fish, as well as looking at ways to reduce the number of animals used by replacing them with non-sentient forms.

Her most recent discovery is that young zebrafish, just days old, feel pain and should therefore be protected by European law.

In this interview, we get to the heart of questions, such as whether fish feel pain, how farming practices need to change, and what the future holds for fish welfare?

Philip:  What led you to becoming interested in fish as a scientist?                

Lynne:  Most of the world is covered by water and fish are the most successful vertebrate group on the planet.

Their ability to live in such a wide variety of habitats and under varying environmental conditions is astonishing. Fish can live in deep ocean trenches under enormous pressure but can also be found at high altitude. I believe their ability to evolve and adapt has allowed them to colonise nearly every available aquatic habitat from polar regions to deserts.

However, what I find most interesting is their behaviour: there is nothing that a mammal can do that we cannot find an example of fish being capable of, from parental care through to tool use. Fish are also an important part of the food chain. I believe it is important to study them and safeguard their health and welfare.

Philip:  How do you respond to someone who says fish aren’t sentient?

Lynne:  Fish can evaluate the actions of others in relation to themselves and third parties. Rabbitfishes form close associations where they forage in pairs. They closely match each other’s behaviour. Whilst one feeds, the other is vigilant, keeping watch for predators and taking turns allowing each other time to forage. Grouper fish form relationships with another species, the moray eel, and they hunt together. Manta rays recognise themselves in mirrors.

Learning and memory research demonstrates that fish can navigate complicated mazes, have numerical skills and can remember for prolonged periods. There are a plethora of scientific studies showing fish can assess risks and benefits, have the potential to experience positive and negative affective states and have some degree of consciousness. These higher order behaviours were thought only to exist in mammals and birds. But now we know fish fulfil the criteria for sentience.

Philip:  What do you think about how fish are raised intensively for food? 

Lynne:  Whilst there have been advances in improving the welfare of farmed fish, I do believe more needs to be done. We still require information on optimal stocking density which should be investigated on a species by species basis since some fish are gregarious whereas others are territorial or aggressive. Environmental enrichment has received little attention for fish, but has been successfully adopted for terrestrial animals.

Keeping fish in high densities can lead to high prevalence of disease. There are few medications to tackle new diseases. Fish will only exhibit overt signs of sickness when very unwell. Automated behavioural monitoring that could identify subtle changes would be a major step forward.

Issues surrounding transport of fish and killing or slaughter also remain to be resolved. Fish should be provided with a humane “good death” but current methods necessarily may result in fear and stress. The same principles that are applied to terrestrial animals ideally should be applied to fish. Fish should be treated as beings that experience poor welfare. We should minimise or avoid practices that reduce welfare.

Philip:  How does your research work help fish?

Lynne:  My research is dedicated to improving the health and welfare of fish. I was the first to identify nociceptors, receptors that detect painful stimuli, in rainbow trout in 2002.

I have co-authored reports on assessing pain where fish were considered for the first time alongside mammals. My laboratory has investigated many applied topics such as enrichment, the effectiveness of pain-relieving drugs, the humaneness of anaesthetics and showing larval fish respond to pain.

This has led me to be invited to talk to scientists, ethicists and lawyers at international conferences but I also provide advice for anyone who asks. I have advised not only public and government bodies, fellow scientists and veterinarians with questions on fish welfare but also members of the public who are perhaps struggling with a moral question on the way they use fish.

Philip:  How do you see the future of aquatic animal biology and fish welfare?

Lynne:  Given the increase in scientists investigating fish welfare I think the future is optimistic.

Results from experimental studies are now being employed to improve the husbandry and treatment of fish. Funding sources are the only hindrance to progress. Improving the health and welfare of farmed and wild caught fish is sensible if we want to ensure that the food that we eat poses no risk to our own health and guarantee sustainability and reduced environmental impact.

Accepting fish are sentient and treating them as such will ultimately enhance the condition of fish. Some of the major challenges in fisheries concern the humaneness of capture methods and slaughter of vast numbers of individuals.

The rise of recirculating aquaculture systems (RAS) and aquaponics concerns me. In RAS ensuring good water quality is key to fish health thus good monitoring systems are crucial. Whilst nature-based aquaponics can be successful, small scale systems, where fish are held in high densities, poses health risks to the fish but keeping these in public areas where fish are subject to noise, vibration etc. could compromise their welfare. Of course more research is required.

Philip:  Thank you.

To learn more about Dr Lynne Sneddon and her work on fish welfare, please click on her website here and visit the F.I.S.H. website.