Paper just published:
Can fish really feel pain?J D Rose, R Arlinghaus, S J Cooke, B K Diggles, W Sawynok, E D Stevens & C D L Wynne
FISH and FISHERIES, 2014, 15, 97–133
http://onlinelibrary.wiley.com/doi/10.1111/faf.12010/pdf (free access)
AbstractWe review studies claiming that fish feel pain and find deficiencies in the methods
used for pain identification, particularly for distinguishing unconscious detection of
injurious stimuli (nociception) from conscious pain. Results were also frequently mis-
interpreted and not replicable, so claims that fish feel pain remain unsubstantiated.
Comparable problems exist in studies of invertebrates. In contrast, an extensive litera-
ture involving surgeries with fishes shows normal feeding and activity immediately
or soon after surgery. C fiber nociceptors, the most prevalent type in mammals and
responsible for excruciating pain in humans, are rare in teleosts and absent in elas-
mobranchs studied to date. A-delta nociceptors, not yet found in elasmobranchs, but
relatively common in teleosts, likely serve rapid, less noxious injury signaling, trigger-
ing escape and avoidance responses. Clearly, fishes have survived well without the
full range of nociception typical of humans or other mammals, a circumstance
according well with the absence of the specialized cortical regions necessary for pain
in humans. We evaluate recent claims for consciousness in fishes, but find these
claims lack adequate supporting evidence, neurological feasibility, or the likelihood
that consciousness would be adaptive. Even if fishes were conscious, it is unwar-
ranted to assume that they possess a human-like capacity for pain. Overall, the
behavioral and neurobiological evidence reviewed shows fish responses to nociceptive
stimuli are limited and fishes are unlikely to experience pain.