The Science Behind Whether Fish Feel Pain
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The Science Behind Whether Fish Feel Pain

Do Fish Feel Pain? The Science Behind Whether Fish Feel Pain

By Stuart Brown, FirstScience.com
September 2003

Do Fish Feel Pain?

"The gull turned its head in rapid, almost robotic movements, as if to verify it was alone, and then it hopped down to where the clam it had dropped lay open on the smooth, hard-packed sand. The clam cracked open like an egg and Jack saw raw meat inside, still twitching, or perhaps that was his imagination. Don't want to see this. But before he could turn away, the gull's yellow, hooked beak was pulling at the meat, stretching it like a rubber band, and he felt his stomach knot into a slick fist. In his mind he could hear that stretched tissue screaming - nothing coherent, only stupid flesh crying out in pain."
- The Talisman - Stephen King and Peter Straub

Pain is not a respecter of intelligence. We tend to assume that the stupidest individual we know is capable of feeling as much pain as we do. We don't tend to say:

"Well, Bob is pretty dumb you know. Are we really sure that he felt pain when that truck hit him? Ok. I know he flew 25 feet in the air, let out a blood curdling scream and then thrashed about for ten minutes. But was that just a motor response? Was he really feeling it?"

We just don't. Bob may be dumb, but pain he most certainly did feel. And yet change it around to say:

"Well fish are pretty dumb you know. Are we really sure that fish felt pain when we hauled it 25 feet in the air with a metal hook in its mouth, juggled it, patted ourselves on the back for a bit, took a picture, then weighed it while all the while it is gasping for air (I did throw it back after all!)" And we aren't so sure.

Fish aren't cuddly. They don't wag their fins at you when you enter the room. They seem distant, aloof, independent, rather like cats really, only without the mitigating fur that is amusing to stroke. Tell me, if you stuck a hook through your cats mouth, dunked him in water and stood and watched while he floundered desperately for air. Would you suspect that might be a painful experience?

Is that same experience painful for a fish though? That is the first question. There is actually rather a lot of science to back up the fact that fish do feel pain. Recent research published in April 2003 by The Royal Society investigated the sensory system of trout through their responses to injections of bee venom and acetic acid around their mouths. In effect the research was trying to find out whether fish possessed the same kind of pain receptors that have already been identified in amphibians, birds and mammals including humans. And secondly, whether the response to the pain producer (i.e. the bee sting etc) was not just a reflex response which might be akin for example to pressing the belly of a talking barbie doll; but rather an actual adverse reaction to the pain stimulus.

What they found was that the fish had 58 such receptors around the mouth and actually reacted at lower levels of pain stimulation then humans, perhaps because their skin is more easily damaged. After the fish were injected with the venom they were observed to show a rocking motion akin to that displayed by other mammals when experiencing stress; they also rubbed their lips on the bottom of the tank and against the walls, and took over twice as long to resume feeding then a control group. The study, which was led by Dr Lynne Sneddon of Liverpool University concluded:

'Administration of noxious substances to the lips of the trout affected both the physiology and the behaviour of the animal and resulted in a significant increase in opercular beat rate and the time taken to resume feeding, as well as anomalous behaviours. The results of the present study demonstrate nociception and suggest that noxious stimulation in the rainbow trout has adverse behavioural and physiological effects. This fulfils the criteria for animal pain.'

In short, they felt pain and reacted to it.

One of the most interesting results of the study is the increase in the length of time it takes for the fish to resume feeding after experiencing pain. This is akin to you falling off your bike as a child and being somewhat reluctant to get back on. Literally the pain is not then just a physical sensation it is psychological. Our poor trout were stressed out. And whilst they are unlikely to win any 'Brain of the Month' awards, it seems churlish to dismiss the feelings they are experiencing as irrelevant simply because they are not making all the mental distinctions we might. Pain is pain is pain when you are the being experiencing it.

And it's not just trout. Another study in the late 80's by Dutch researcher John Verheijen investigated the reaction of carp to being caught with a hook and then released. They found that carp that had been caught and then released abstained from feeding for a considerably longer period of time, and showed stress type behaviour like making rapid darting movements, spitting, diving and shaking their heads. The study concluded that the fish felt pain from being hooked, but that their behaviour was mostly a fear response to possibly being caught again. In effect then, in a similar way that a victim of violent crime may get over the physical injuries quite quickly, but be traumatised for far longer, the fish showed a similar trauma response to being caught.

Sense a pattern emerging here? The RSPCA certainly seem to think so. A report by the RSPCA in April 1994 concluded:

"There is little to support the supposition that animals with larger brains experience pain in a more meaningful way than those with smaller brains; simply that they use neural structures similar to our own to interpret it. There is no reason to believe that fish are not achieving the same processing effect in other parts of the Central Nervous System. All the fundamental structures and modulation processes necessary to achieve a perception of pain are present in fish."

And even today on the RSPCA website in giving advice to potential fish owners for their own home aquariums, they advise:

"Fish are very delicate and sensitive. They should not be caught and moved by hand as this is very distressing for them and they are easily injured."

So, let's go with our common sense here. The UK's leading animal charity reckons that even handling your pet fish in a rough way causes them distress. What do you suppose shoving a hook through their mouth, juggling them in the air while you get them on a set of scales and watching them gasp for air might do for their state of mind? Probably not very calming for them I suspect.

Ok. So angling is not a great experience for our friend the fish. What about commercial fishing. Is that any better from a 'pain' perspective? In short, no. It is much worse. What typically happens in commercial fishing is that the boats now use enormous drift nets that are sometimes miles long to scoop tons of fish.

  • First off these also have the immediate effect of killing dolphins, porpoises and turtles in their masses.
     
  • Secondly, as these nets are dragged along the fish are squeezed and bounced against each other, often for hours at a time, and as "fish are very delicate and sensitive" we can only imagine what that must feel like as their scales are rubbed either against each other, or even in the mesh of the nets themselves.
     
  • Thirdly, as these nets can be dragged up from great depths the fish might also have to contend with the pressure changes that brings, which can cause internal rupturing, eyes to pop out of their sockets and stomachs to pop out of their mouths. This is really no different from a diver that gets 'the bends' because they have come to the surface too quickly. We have hyperbaric chambers to help us out when we do this, but the fish obviously does not get the same courtesy.
     
  • Fourthly, even when the fish makes it to the surface its suffering isn't over, because they are then dumped unceremoniously onto the decks of the trawlers where they not only cannot breathe, but also stand a good chance of being crushed to death as the weight of the rest of the catch piles down on top of them.
     
  • Fifthly, as if they haven't put up with enough in terms of 'nightmare ways to die' they are then either manhandled, often by pitchfork, some being stabbed in the process, into holds ready to be taken back to shore or if they are non-target fish (“bycatch”), then they may be thrown overboard having just effectively been tortured, suffocated and stabbed. Nice.

Now, that's not great. But this is all a positive procession of luuurve in comparison with what our pink friend the lobster has to contend with. None of that gentle preamble torture stuff. Oh no. Screw him. "Let's boil him alive! He tastes better that way!"

It is a widely held belief that lobsters do not feel pain. Think again. Oxford University zoologist Dr. John Baker, found that lobsters dropped into boiling water, showed "powerful struggling movements" for up to two minutes and he concluded that these were not reflex actions but indications of pain. He also experimented with other methods of cooking them, such as starting off with the water cold and then gradually heating it, but concluded that this just led to more prolonged suffering.

Lobsters can live for over 100 years and carry their young for 9 months. Like us. And according to invertebrate zoologist Dr Jaren G. Horsley, "The lobster does not have an autonomic nervous system that puts it into a state of shock when it is harmed. It probably feels itself being cut... I think the lobster is in a great deal of pain from being cut open... and feels all the pain until its nervous system is destroyed" during cooking.

Now, think of when you last spilled hot tea or coffee on yourself. Did it hurt? Now imagine being boiled alive in a bath of boiling water. If you thought a lobster had even 10% or 1% of your capacity to feel that pain do you think it might be just a little cruel to do what we do now?

"Ok. Ok. Lobster's out. But what next? Worms? Wasps? Plants? Should I stop eating asparagus now because it might be having a bad day. If my tomatoes scream out in pain where is there to go? I GOTTA EAT SOMETHING!!!"

Calm down. I feel your pain! Just use your head and try to limit it to inflicting it on yourself and the people around you, and not the rest of the planet! Personally I have a simple philosophy when it comes to food and life in general. If it once breathed I don't eat it, and I try not to harm it. Have I ever squashed a worm or splatted a wasp? Absolutely. I try not to make a habit of it, and if I do it is generally an accident. I don't much like wasps and frankly I am not going to start up a 'Wasp Protection League' anytime soon. The less of them in my house the better. But unless they are attacking you or you are allergic to them (in which case splat away - self preservation baby!) then what's the harm in putting a glass around them and letting them fly away into the garden? Who knows, they might even do you a favour and sting the neighbour you don't like!

There is actually some research that indicates that plants do have some kind of response when we cut them, as they release a chemical called ethylene which seems to control factors such as cell growth. However, plants are devoid of nervous systems, nerve endings, and brains and so although it is feasible to reason that anything that is living can exhibit a response to physical stimulus, it seems far-fetched to attribute pain to plants because they cannot have a perception of pain. In any case, on the plant front I do think a line has to be drawn in the sand. When that lobster gets lowered into the boiling waters he will feel pain, and you can bet your house that it is more then even the most caring, sharing tomatoe! Pain minimisation has got to be the order of the day, not sainthood. Screw aubergines and tomatoes I say! Kill the vegetables! Save the animals! They really ARE feeling pain and KNOWING IT is someway along the path to helping to STOP IT.

Recommended Links To Learn More:

Trout trauma puts anglers on the hook?
Fish Photo Gallery: Wishful Thinking vs. Reality
Vegan Seafood: Beyond the Fish Shtick for Vegetarians
Fact of the Day: Scientific evidence proves that fish do in fact, feel pain and react to it.

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The calf photo on these pages is from Farm Sanctuary with our thanks.

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