By Rachel Clark, Cohen Hocking and Victoria Pollins

• Summary of Rose et al. 2012
– What is pain and how is it detected?
– Review and critique of fish pain literature
– Are fish conscious?
• Other scientific opinions
• Social side of the argument
• Conclusions and discussion

• Critique paper on current research regarding fish pain.
• Describes how methodologies used thus far are not adequate for concluding that fish feel pain
• Most research on fish welfare driven by emotion and opinion. Lacked scientific approach

• Easy to identify pain in humans: communication!
• Non-humans:
– although we can use imaging to see brain activation in response to injury infliction, we can’t conclude that this is associated with conscious feelings of pain

• International Association for the Study of Pain
(IASP):
– pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage. It is a subjective state.

• Nociception:
– “unconscious detection of injurious stimuli”
– Nervous system sensing noxious stimuli
• In humans, nociception is transmitted to the cerebral cortex and is translated into pain
• Although most animals have nociception, only mammals have cerebral cortex structures necessary to create human-like pain

• Back bone of Rose et al.’s (2012) paper:
– Unconscious nociception ≠ conscious pain
– Although, commonly grouped together
• Distinguishing between nociception and pain by analyzing behavior is very difficult
– Removal of cerebral cortex in mammals results in no behavioral changes (Berridge and Winkielman 2003)
– Avoidance learning also possible
(Kotanai et al. 2003)
• Behavior can only tell you how noxious a stimulus is but not whether it’s causing pain.

• Construct: an attribute or ability that happens in the brain (ex: English language proficiency)
• Construct Validation: The degree to which a test measures the construct it claims to be measuring
– Is research actually testing for pain, or are they only measuring nociception?

• Le Bars et al. (2001), Blackburn-Munro (2004), Vierck (2006),
Rose and Woodbury (2008), and Vierck (2006)
• “None of these tests can be legitimately viewed as tests of pain, because the target behaviors can be expressed without consciousness” (Rose et al. 2012)
• Validated model: greatest challenge to pain research

• Mammals: because they have same cortical regions as humans needed for processing pain, we can infer pain by cortical activity
• However, “this approach cannot be used because the fish brain does not contain [a true cortex]… a fact that has led to the conclusion that pain experience meaningfully like humans is probably impossible for fishes”
(Rose 2002,
2007, from Rose et al. 2012)

• Behavioral Studies
• Surgery, Wounding, Electronic Tagging
• Neurological Studies

• Bateson 1992: pain detection criteria
– Animals able to detect noxious stimulus, react negatively to it, learn to avoid it, and that the behavior is not a “simple reflex”
– Rose et al. 2012: conclude that these criteria do not distinguish pain from nociception

• Sneddon 2003a
– Injections of bee venom into jaw of trout
– Rocking, mouth-rubbing, increased opercular beat rate, delayed feeding
– Rose et al. 2012: not validated detectors of pain
• Sneddon 2003b
Morphine injections reduced mouth rubbing
Rose et al. 2012: morphine acts on nociception

• Wagner and Stevens (2000), Newby et al. (2007),
Moser et al. 2005, Connors et al. 2002, Cooke et
al. (2002)
– Surgical insertion of transmitters (usually into peritoneal cavity)
– No response in feeding and swimming behavior
– No response to migration
– No changes in social behavior, parental care
• “If these fish were experiencing pain, we would infer that they would exhibit severely altered behavior”

• A-Delta Fibers
– “bright pain”: immediate, localized
– Signal possible injury to trigger escape/avoidance
• C Fibers
– Burning, dull pain. Long lasting, diffuse.
• Roques et al. (2010)
– 5% of sensory fibers in common carp are C fibers
– However, it wasn’t determined if these C fibers were nociceptors or non-nociceptors

• “… [meaningful] pain experiences like in humans is probably impossible for fish” (Rose
2007)
• Pain is a process dependent on consciousness
– Need to prove fish are conscious to prove they feel pain

• What is consciousness and how is it identified?
• How plausible is it the fish could be conscious
• What evidence is there for consciousness in fishes
• What value would consciousness be to fishes and at what cost
• If fishes were conscious could we comprehend what that consciousness is like (Ross et al. 2012)
• Effects on scientifically-based fisheries policy

“Wakefulness is not evidence of consciousness because it can exist in situations where consciousness is absent” (Laureys 2005).
“Assessment of pain depends on verbal interaction, thus an animal under anesthesia that awakens, is mistermed when you say it has regained consciousness” (Rose et al. 2012)

• No agreed definition of consciousness in animals (Rose et al. 2012)
• Can only agree on consciousness based on verbal communication (Bruno et al. 2011)
– Exception: locked-in syndrom
– Science cannot elaborate on behaviour

• Consciousness depends on specific identified neural structures (Rose 2002).
• In mammals the cingulate gyrus is a layer of the mesocortex which is critical for conscious awareness of pain, emotional feelings, and self awareness

• Fish pallium cannot function like the cortex for the purpose of pain and consciousness (Rose
2002)
• Inadequate techniques used to identify nociceptic activity reaching the pallium

“Anyone proposing that a fish pallium could function like a human or mammalian neocortex or that there might be a substitute system in fish brains for generating consciousness, must provide convincing, empirical evidence that such a proposal is worth consideration. This has not been done.”
(Rose et al. 2012)

• Much of human survival behaviour is actually conducted by the unconscious (Wilson 2004)
– Sizing up the world
– Warning of danger
– Setting goals and sophisticated action
• Behavioural complexity is not evidence for consciousness
– Eg. Individual recognition; avoidance learning
(Rose et al. 2012)

• Removal of the cerebral hemisphere results in minimal changes to neurological behavior
(Overmier and Hollis 1983)
– Food (yes)
– Spawning (yes)
– Intraspecies aggression (yes)
– Smell (no)
– Avoidance conditioning (yes, but difficult)
• Basic patterns of fish behavior controlled by lower brain structures (diencephalon, brainstem, and spinal cord)

• No one knows!
– Those who argue consciousness, assume they would experience human-like pain and suffering
(Rose et al. 2012)
• Rose argues that if fish were conscious, it would be so different from human consciousness, no one can speculate on what that would infer

• Most behavior in fish is reactive
– Not much value in conscious behavior (ie, natural selection)
– Conscious suffering would likely be selected against since it is unlikely to benefit fishes (ie, little can be done to treat wounds) (Rose et al.
2012)

• Even scientists who believe in primary consciousness, do not believe fish are selfaware (Donald 2001, Tulving 2005)
– Self awareness facilitate dissociation techniques for reducing pain (Price 1999)
– Yet, others believe a lack of self-awareness would make pain and suffering more intolerable
(Sneddon 2011)

• Misinformation on policy making (Rose et al. 2012)
– Describes EU fish policies as scientifically unsound
– Benefit of the doubt ideology is not scientific justification (Dawkins 2012)
– Too much focus on feelings, not enough on function

“We believe that in fostering fish welfare, implementation of legislation must be intelligently considered to ensure that it would not adversely impact humans socially and economically without necessarily benefiting fishes” (Rose
et al. 2012)

• Though teleost fish are different in brain structure than tetrapods, brain function is similar
(Chandroo, Duncan, and Moccia 2004)
• (Response to Rose et al. 2002) says nociceptors are actually similar to high animals like humans
(Braithwaite and Huntingford 2004)
• Studies in zebrafish opioid receptors and peptides have been shown to function in a similar way to tetrapods
(Gonzales-Nunez and Rodriguez 2009)

• Can’t communicate a subjective account of pain (human standard), so observing behavior must be our only criteria for animal pain
(Sneddon 2009)
• Behavior is altered by noxious stimuli showing they’re making decisions, not simply reacting impulsively
(Sneddon 2009)

• Studies have shown fish display adverse behavior to physical injury to tissue as well as suspend normal behavior
(Sneddon 2009, Sneddon 2003,
Ehrensing 1982)

• In recent years, animal brain function has been shown to be higher than ever thought for nonhigher order primates
1) Corvids capacity to learn to anticipate the intensions of others
(Emery and Clayton 2001)
2) Rats show pessimism and optimism
(Harding and Mendl
2001)
3) Rhesus macaques can give perception of their memory for a specific event
(Hampton 2001)
4)Fish have shown to create mental maps
(Braithwaite and Huntingford 2004)

• Solipsism: “idea that only one’s own mind is sure to exist… outside of one’s own mind is unsure”
(online etymology dictionary)

• Until 1989 Vets were taught that animals didn’t feel pain
(Rollin and Bernard, 1989)
• Animal intelligence research

“Less sensitive are their bodies, the more can they tolerate extreme pain or the rapid alteration of heat and cold; when they are exposed to illness, the more rapid their recovery from wounds that would be fatal for more sensitive peoples”
Christopher Meiners (1747 – 1810)

“All the arguments to prove man's superiority cannot shatter this hard fact: in suffering the animals are our equals.”
Peter Singer (1946 - present)

“the results of many studies lead to believe that fish have the structures necessary and the capacity to experience fear and pain and can thus suffer and therefore, welfare considerations for farmed fish should take these into accounts” –EFSA (European Food Safety
Authority)

• Sneddon believes that research is needed for
“species specific response to pain, analgesics and doses”
(p.341 Sneddon 2009)

• Sneddon believes that research is needed for
“species specific response to pain, analgesics and doses”
(p.341 Sneddon 2009)
• But what about the wild fish?

Citation: Hinch 2015

• Estimates of global fish catch are as high as almost 3 trillion individual fish per year (Mood and
Brooke 2010)
• If sentient, should we regulate how we handle fish?
• How will this effect the fishing industry?

• “many existing commercial killing methods expose fish to substantial suffering over a prolonged period of time”
(EFSA 2004)

• Currently no fish welfare regulations are in place anywhere in the world
(Singer 2010)
Except for fish farms
• Norway has banned C0
2 stunning and
• Germany has banned ammonia baths

• Prevention of Cruelty to Animals Act
• Milk Industry Act/Milk Industry Standards
Regulation (for cattle)
• Meat Inspection Regulation (for animals during slaughter)
• Food Safety Act Agricultural Produce Grading
Act (i.e. for poultry)

Recreational
• Hook and line, throw nets, spear fishing, noodling
Commercial
• Long line
• Trawls and dredges
• Seine
• Traps and pots
• Gill nets
Bycatch?
(Hinch 2015)

Currently the scientific community remains divided on whether fish feel pain
An “ethical” transformation of the global fishing industry may be unrealistic

• So do you think fish feel pain?

• If they do feel pain, should this affect our fishing practices?
• Is scientific uncertainty enough to justify a change in fishing practices?

• Given the array of studies on fishes (and other animals) to feel pain, do you think this poses issues of animal cruelty (eg. Injecting acid into the mouths of animals to test pain response)? Or is the research justified in the name of science and policy making decisions?
• Do you think it is to the advantage of marine fisheries for a paper like this to be published?

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