Maneka Sanjay Gandhi
The International Association for the Study of Pain defines pain as “an unpleasant sensory and emotional experience associated with actual or potential tissue damage. The inability to communicate verbally does not negate the possibility that an individual is experiencing pain.”
It seems extraordinary that it has taken us so long to ask the question – do fish feel pain. Accepting that an animal has the ability to suffer pain, changes the way we choose to interact with it. It should influence the moral and ethical judgements we make.
Victoria Braithwaite, in her book “Do Fish Feel Pain”, presents scientific evidence that fish are smart and cognitively competent beings. This coincides with hundreds of studies showing that fish are intelligent and have both accurate and long lasting memories, which in some cases, such as migrating salmon, can span years. Fish don’t audibly scream when they’re impaled on hooks, or grimace when the hooks are ripped from their mouths, but their behaviour offers evidence of their suffering—if we’re willing to look.
Fish have all our senses and more. A thin lateral line runs along the flank, with special sensory receptors, which allow the fish to detect nearby objects. Blind-cave fish, living in underground caverns in Mexico, use this for ‘seeing’. The electric eel, with a specialised organ located towards the end of the tail, can generate enough electricity to stun prey. Knife-fish, or elephant-nose fish, generate weaker electric signals used for communication.
Are fish so different from humans? Conspicuous parallels emerge. Apart from the backbone, their ‘stress response’ is strikingly similar to that of mammals.
The fish brain also has a forebrain, midbrain and hindbrain. However, fish do not have a neocortex. This plays a central role in the fish pain debate – even those who argue fish cannot feel pain consider the neocortex essential for an animal to experience feelings. MRIs show us that the neocortex isn’t the only part of the brain that is active during painful events. Many other parts of the brain overlap and take on functions. Dr. Ian Duncan reminds us that we “have to look at behaviour and physiology,” not just anatomy. “It’s possible for a brain to evolve in different ways. That’s what is happening in the fish line. It’s evolved in some other ways in other parts of the brain to receive pain.”
Fish, like “higher vertebrates,” have neurotransmitters, such as endorphins, that relieve suffering. Researchers have created a detailed map of pain receptors—which includes those very areas where an angler’s barbed hook penetrates. As Dr. Stephanie Yue writes, “Pain is an evolutionary adaptation that helps individuals survive. A trait, like pain perception, is not likely to suddenly disappear for one particular taxonomic class.”
A nociceptor is a sensory nerve cell that responds to damaging, or potentially damaging, stimuli by sending signals to the spinal cord and brain. It initiates the sensation of pain (noci is Latin for “hurt”) Nociceptors in fish are strikingly similar to those found in mammals, and they respond to heat, pressure and noxious chemicals such as acid and bee venom.
In 2004, physiologist Lynne Sneddon published a study saying that fish can detect and feel pain. Sneddon discovered 58 pain receptors, called nociceptors, along the trout’s lips resembling those in amphibians, birds and mammals including humans. She did so by injecting bee venom and acetic acid into the mouth area. The affected fish exhibited behaviour that clearly showed extreme stress, such as rubbing their noses into gravel and shaking their bodies. Fish demonstrated a ‘rocking’ motion, strikingly similar to the kind of motion seen in stressed higher vertebrates like mammals. Since morphine appeared to ease the discomfort, Sneddon concluded that the trout’s reactions weren’t simply reflexive but genuine displays of pain response. The fish injected with venom and acid also took almost three times longer to resume feeding than the control groups.
Trout are “neophobic,” – they actively avoid new objects. But those injected with acetic acid showed no reaction to a brightly coloured Lego tower placed in their tank, suggesting that their attention was focused instead on the pain. In contrast, trout injected with saline — as well as those who were given painkillers following acid injection — displayed the usual degree of caution regarding the new object. Similar results have been demonstrated in human patients suffering from painful medical conditions. We all know that pain interferes with our normal thinking abilities.
Researchers at Purdue University in Norway reported that goldfish experience pain consciously. Goldfish injected with saline solution, and exposed to a painful level of heat in a test tank, “hovered” in one spot when placed back in their home tank. Fearful, avoidance behaviour is rational — not involuntary. Other fish, after receiving a morphine injection, showed no such fearful behaviour.
Commercial fishing frequently depends on gill nets – walls of fine netting in which fish become snared, often by the gills. They may suffocate in the net, because with their gills constricted, they cannot breathe. The first ever systematic estimate of the size of the yearly global capture of wild fish is about 1 trillion – 2.7 trillion; about 150 times the number of mammals and birds killed for consumption.
Can a planet survive after so much pain has been generated? There is so much violence in the air that we breathe it. Can we be happy if every being around us is unhappy? The miasma of viciousness hangs like a black pall over us. No wonder we are so miserable ourselves.
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