Fish do feel pain according to science

The most recent evidence solves a moral question that has been debated for years, and that science wants to answer. The question is what to do about it.

In 2016, neurobiologist Brian Key wrote the article “Why don’t fish feel pain? he argues, happens in the cerebral cortex, that region of the brain associated with conscious experience and thought. It is a complex system of emission and reception of information.

According to Business Insider, this means that the crust doesn’t just turn a stimulus, a prick, into a reaction, like removing your hand. That’s just one way: action-reaction. Instead, the crust turns the sensation over: hence the pain. 

Fish, which lack cerebral cortex, in theory, does not suffer from this “tail-flick”, so any behavior that “looks” painful, such as wriggling when pulled out of the water, is just that, a behavior, not a sensation. Key ended up in the limelight, and not at the hands of animalists, but by some 40 scientists who jumped into debating the evidence, he presented in Animal Sentience, an interdisciplinary journal about the sensation of animals.

His fellow neuroscientists, Hanna and Antonio Damasio, professors at the Brain and Creativity Institute at the University of Southern California, were among the detractors. In a study published in 2016, they explain that pain does not only occur in the cortex, at least in humans, and that it is a behavior – or a sensation, or a response – much more complex even in simpler organisms, such as fish that, although they do not have a cerebral cortex, do have a kind of nervous system.

In another 2014 study, a team of zoologists from Macquarie University, Australia, conducted an analysis of everything published since 1975, when science began trying to solve the moral question of whether or not fish felt pain. They concluded that fish cognition and sensory perception are on par with that of other animals.

It is true that fish do not feel pain like humans, but there was not enough evidence to prove that fish did not feel pain, and there was not enough to say that they did. Up to now.

The Smithsonian Museum and Research Center published an article claiming that the verdict is “yes, they feel pain.” He quotes biologist Victoria Braithwaite, who for 15 years has accumulated evidence that fish, like mammals, feel pain. Braithwaite told the BBC in 2014: “It is impossible to know if another creature’s experience is like ours. But fish do feel pain. It’s probably different from what humans feel, but it’s still kind of a pain. “

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At the anatomical level (explains the Smithsonian) fish have neurons known as nociceptors that detect potential damage and, when faced with a threat, produce opiates, the same natural painkillers that mammals produce.

Fish also behave indicating that they are suffering. In a study cited by the Smithsonian Research Center, researchers threw colored Legos into tanks with rainbow trout, which normally avoid foreign objects. When the scientists injected the trout with acetic acid, they exhibited fewer defensive behaviors, presumably because they were distracted by their own suffering. Those who injected with morphine remained wary.

Key’s notion that fish do not have the brain complexity to feel pain is, in the critics’ words, outdated. Although not all vertebrates are conscious, even if they do not have a cerebral cortex as extensive as ours, this is not a prerequisite for subjective experience, according to the article from the research center. A mind must not be human to suffer ”, he concludes.

Other studies support this idea, so much so that the collective evidence is now robust enough for biologists and zoologists to accept fish pain as reality.

Given the new information that science offers us, the challenge is what to do with it. In some countries like Norway, fish farmers have taken more “humane” measures to kill fish. Instead of suffocating them, they are shocked or put into buckets of ice water to freeze, or poisoned with carbon dioxide, and killed more quickly.

Although there is still no full consensus on whether or not fish feel pain (like saying, for example, that the earth is round), the evidence is gradually accumulating and leaning towards a yes. The question now is whether these animals should receive the same attention as bulls in bullfights and cattle and pigs in slaughterhouses. For now, and according to the FAO, human consumption of fish was 20 kilograms per person in 2016, which means that millions of fish die, apparently in pain, every year.