Prof Alan Roberts, in giving his opinion on the ability of fish to experience pain (Can fish feel pain? The jury is still out, Letters, 7 April), neglected to mention the wealth of published scientific evidence outside of behavioural and hormonal responses.
I was the first to identify the existence of nociceptors in a fish, the rainbow trout, in 2002. These are specialised receptors for detecting injury-causing stimuli, and their physiology is strikingly similar to those found in mammals, including humans. Since then, my laboratory and others across the world have shown that the physiology, neurobiology, molecular biology and brain activity that many fish species show in response to painful stimuli is comparable to mammals.
Further, adverse changes in behaviour are seen when fish experience pain, such as suspension of feeding, reduced activity, anomalous behaviours and failure to show appropriate behaviour to competing stimuli – for example, fear and predator stimuli. These changes are prevented by the use of painkilling drugs.
Together, these empirical studies provide compelling evidence for fish experiencing pain, and legislation such as the Animals (Scientific Procedures) Act 1986 as well as bodies such as the Farm Animal Welfare Committee state that pain in fish should be avoided, minimised or alleviated.
The published scientific evidence shows that cats, dogs, birds and other vertebrate animals feel pain. There are also many studies on aquatic invertebrates that demonstrate pain in crustaceans (crabs, lobsters) and cephalopods (octopus, squid and cuttlefish).
Therefore the jury has made its decision and left the building. It is clear that there is ample evidence for pain in fish, and I agree with Prof Roberts that we need to safeguard the welfare of these important animals and treat them with the same consideration that we give mammals.
Dr Lynne Sneddon
University of Gothenburg, Sweden