[Paleopsych] fish feel pain in a similar way to humans and other mammals

[K.E.]

Does she have feelings, too?
(Filed: 02/03/2005)

the idea that fish feel pain in a similar way to humans and other mammals
has split scientists


A fierce debate is raging about whether fish are sentient beings that feel 
pain. Sanjida O'Connell reports

The goldfish might have a reputation for having a three-second memory,
but scientists are realising that fish are much smarter than most of us 
give them credit for.
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Now, at a forthcoming conference on sentience in domesticated animals,
an expert is to argue that what really matters is not IQ but emotions,
and that fish can suffer as much as birds and many mammals.

The claim of Professor Ian Duncan of Guelph University, Canada, will attract
praise and condemnation in equal measure. Supporters include the organiser
of the conference, the Compassion in World Farming Trust, which is concerned
about the welfare of farmed fish, its agenda being to achieve wider
recognition of farm animals as sentient beings.

Some animal rights groups go further. People for the Ethical Treatment of
Animals, for example, says: "Many people never consider the terror and
suffering that fish endure when they're impaled by a hook and pulled out of
the water. In fact, if anglers treated cats, dogs, cows or pigs the way they
treat fish, they would be thrown in prison on charges of cruelty to animals."

The angling community dismisses such claims as "debate driven by prejudice
and sentiment". Charles Jardine, director of the Countryside Alliance's
Campaign for Angling, denies that fish can feel pain, adding: "I have spent
my whole life fishing and I wouldn't do it if I thought it was cruel."


Although scientists have spent years examining cognition in other animals,
fish have been neglected. Now, according to Dr Keven Laland of the
University of St Andrews, fish are thought to have long-term memories and
some can even be compared to non-human primates in terms of their social
skills.

What is important, according to Prof Duncan, is how an animal feels. He
says: "We assume human beings have a worse time than animals do because we
have the cognitive ability to imagine all the different things that can go
wrong in our lives. But the converse might be true." Imagine, for instance,
a person with a broken arm and a fish with a torn fin. "The pain may be
extremely severe in both cases. However, the human being's cognitive ability
might help her `think about other things'." But because animals such as fish
cannot think like us, their pain might be all-consuming.

How do we know fish feel pain? In 2003 Dr Lynne Sneddon of the University of
Liverpool published the first evidence that fish have pain receptors like
ours. Nociception is the ability to detect painful stimuli. Dr Sneddon
showed that fish, like humans and other higher vertebrates, have nociceptors
that respond to chemicals, heat and pressure.

However, sceptics, such as Dr James Rose of the University of Wyoming,
Laramie, author of a scientific paper on fish pain, think this does not show
that fish suffer. Dr Rose says: "The presence of nociceptors in fish makes
sense, but nociception is not the same thing as pain and can occur without
pain. Consequently, the presence of nociceptors is not proof that fish are
capable of experiencing pain." In other words, if you touch a hot stove,
your nociceptors will fire and trigger a reflex action - you'll snatch your
hand away. You will then feel pain; what Dr Rose argues is that fish have
reflex actions that prevent them from being injured, but feel nothing.

Dr Sneddon has just published some work that many believe refutes the
sceptics. She injected rainbow trout either with a salt solution, which was
unlikely to cause them any discomfort after the initial injection, or with
bee venom. The ones injected with the saline solution continued to feed and
behave as normal. The others stopped feeding for almost three hours, rocked
from side to side and rubbed their lips against the gravel and sides of
their tank. The breathing rate of the venom-injected fish also doubled, like
a person in pain might hyperventilate. "These complex behaviours have not
been recorded in fish before and may be pain-coping strategies."


Dr Rose disagrees. He suggests that her study shows the opposite - that
trout have a remarkable tolerance of trauma, since the fish resumed feeding
in just less than three hours. "The most impressive thing about the venom
injections was the relative absence of behavioural effects, given the
magnitude of the toxic injections. How many humans would show little change
in behaviour or be ready to eat less than three hours after getting a
lemon-sized bolus of bee venom in their lip? Moreover, the behaviour
described may have been nociceptive responses, but there is no reason to
believe they reflected conscious pain."

Dr Sneddon retorts: "Dr Rose doesn't understand how these things work - he
doesn't work on pain, he just wrote a review about pain in fish. The bee
venom causes an acute short-lasting stimulus that in other animals and
humans has an effect that lasts for three hours. So the fish show quite an
intense response at the start and then the physiological effect subsides
over three hours, the same as it does in humans."

The second part of Dr Sneddon's study consisted of giving the trout
morphine. Almost immediately, the trout that first had the venom started to
feed. She concludes: "The trout's behaviour and responses were affected by
the venom. They have the same pain-sensing apparatus that we have. The bee
venom would be painful to us, so therefore it's likely that it was painful
to the fish." She admits the study is controversial, adding: "We can never
tell what an experience is like for another animal. No one has ever been a
fish, so we don't know what it is like."

Dr Rose remains to be convinced. His argument centres on how the brain
processes pain. He argues that in humans pain perception is computed by the
neocortex, the outer layer of the brain. "Fish have no brain regions even
remotely comparable to these human neocortical regions," he says.
"Consequently, this is a simple hardware question - fish don't have the
brain hardware necessary for either consciousness or pain."

John Webster, an emeritus professor at the University of Bristol, whose book
Animal Welfare: Limping towards Eden has just been published, says: "A
powerful portfolio of physiological and behavioural evidence now exists to
support the case that fish feel pain and that this feeling matters. In the
face of such evidence, any argument to the contrary based on the claim that
fish 'do not have the right sort of brain' can no longer be called
scientific. It is just obstinate."

It is debatable whether fish can suffer, but if they do feel pain, should
that alter how we treat them? Three studies record an 80 per cent mortality
rate for fish such as mackerel and sole caught by trawlers and thrown back
into the sea. If fishermen hook fish in the skin or the mouth, the majority
recover, but if the fish swallows the hook or it catches any other part of
its anatomy, it will subsequently bleed to death. Currently, two main types
of hooks are used by anglers - octopus hooks and circular hooks. Circular
hooks cause less damage: if the hook is easy to remove, 95 per cent of fish
survive, whereas 15 per cent more die when an octopus hook is used.

Dr Sneddon says: "People should think more clearly about how they handle
fish and what they subject them to. It's up to individuals whether they eat
fish, but it's an important food so the government should invest money in
equipment to make the experience of being caught less invasive for fish. As
for fishermen, they should know that what they do causes fish pain and it's
up to them to decide whether they want to continue angling."

The Compassion in World Farming conference on animal sentience is in London
from March 17-18; http://www.animalsentience.com/

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12 October 2004: QED: fishy business [fish are not clever]
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6 October 2004: Fast-learning fish have memories that put their owners to shame
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----
Karen Ellis

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