Let's stop asking if fish feel pain

Recently I was reminded all-too-clearly of how some people still perceive fish. I was telling a friend about an excellent book I had just finished reading, ‘What A Fish Knows’ by Jonathan Balcombe, when she said something I have heard many times: “I mean, fish don’t feel pain, do they?”

Indeed, just 10 years ago, the question 'Do fish feel pain?' was common, both in the scientific community and with the public at large. Unfortunately, at the time, it was also commonly thought that the answer was no. Since then, there has been a wealth of research to support the fact that not only do they feel pain, but they are also capable of fascinating behaviours and cognitive feats. And, while a minority may still be unconvinced, the majority of the public recognises that fish feel pain: a 2018 study by Compassion in World Farming showed that two-thirds of adults across nine European markets agree that fish are sentient and that fish feel negative emotions, while just 13% agree that fish do not feel pain.

ANATOMY

One reason for any scepticism is that we largely view the world through a human lens. If fish cannot feel pain in the same way that humans do, then many may conclude that they must not feel pain at all. Fish do not have a neocortex - the complex outer layer of the brain humans have that is responsible for our cognition and sensory perception. But the belief that to feel pain, you need a neocortex like the one found in the brains of mammals is misplaced. Birds do not have a neocortex either - they have what is called a paleocortex instead. And it is well recognised that if mammals are conscious, so are birds. Birds, therefore, quash the idea that you need a neocortex to be conscious. As Lori Marino from Emory University says, "to suggest that fishes cannot feel pain because they don’t have sufficient neuroanatomy is like arguing that balloons cannot fly because they don’t have wings." Or as Jonathan Balcombe writes “Or that humans can’t swim as they don’t have fins!” It turns out fish have an area called the pallium that appears similar in function to the neocortex. While there is less computing power than the average primate neocortex, it is extremely diverse and complex. And functions for fish the way the paleocortex and neocortex function for birds and mammals.

Like us, fish are vertebrates and contain many of the same structural elements that we do; a skeleton, vital organs and most importantly in this context, a nervous system with sensory receptors. Unfortunately for fish, though they are built the same, they look incredibly different to us. On the whole, humans are much more likely to empathise with individuals that look, and live, like them.

BEHAVIOURAL STUDIES

Of course, the other factor that stops humans from immediately seeing that fish experience pain is that fish don’t scream out when they get hooked, or cry tears when nursing a damaged fin. However, if we look closely at the behaviour of fish and attempt to move away from our human-centric understanding of pain responses, we can see that fish do indeed react when exposed to painful or harmful stimuli. In a study by Garner and Nordgreen, fish responded to exposure to high heat by wriggling profusely and trying to distance themselves from the hot object. Not only this, but following the study the fish demonstrated unusual behaviours for some time, such as incessant tail-flicking and swimming (reflective of escape responses). Perhaps the most convincing element of this study is that in a group of fish that were given a dose of morphine to deal with the painful stimulus, normal behaviour was exhibited following the painful encounter. This indicates that painkillers are effective on fish, implying that pain is a very real experience for fishes.

A DROP IN THE OCEAN

The studies I’ve shared are but a drop in the ocean of the vast amounts of research on the lives of our fishy friends. Many high-profile scientists and ethologists share the belief that we have ample proof that fish feel pain. It is without a doubt that fish are worthy of our respect and of protection against harm. Fish are intelligent in many ways and you only have to watch an episode of BBC’s Blue Planet to be awe-struck by their abilities, like the camouflage of a cuttlefish or thetool use exhibited by a determined tuskfish. With as many as 77 million farmed fishes reared and killed in the UK every year in incredibly inhumane conditions, it is vital that we extend our knowledge and compassion not just to the land but also the sea. So let's keep them off our plates and in our hearts, and make the world a better place for them.