Pain in fish
Encyclopedia
The presence of pain in an animal, or another human for that matter, cannot be known for sure, but the possibility that animals experience pain can be inferred through comparative brain physiology and physical and behavioral reactions. Some specialists currently believe that all vertebrates feel pain, and that certain invertebrates, like the octopus, might too.
Animal protection advocates have raised concerns about the possible suffering
of fish caused by angling
. In light of recent research, some countries, like Germany, have banned specific types of fishing, and the RSPCA (which has authority in England and Wales) now formally prosecutes individuals who are cruel to fish.
as human beings feel it traces back to the 17th-century French philosopher, René Descartes
, who argued that animals do not experience pain and suffering, because they lack consciousness
. Bernard Rollin
of Colorado State University, the principal author of two U.S. federal laws regulating pain relief for animals, writes that researchers remained unsure into the 1980s as to whether animals experience pain, and veterinarians trained in the U.S. before 1989 were simply taught to ignore animal pain. In his interactions with scientists and other veterinarians, Rollin was regularly asked to "prove" that animals are conscious, and to provide "scientifically acceptable" grounds for claiming that they feel pain. Carbone writes that the view that animals feel pain differently is now a minority one. Academic reviews of the topic are more equivocal, noting that although the argument that animals have at least simple conscious thoughts and feelings has strong support; some critics continue to question how reliably animal mental states can be determined.
Veterinary medicine uses, for actual or potential animal pain, the same analgesics and anesthetics used in humans.
Additional tests conducted at both the University of Edinburgh and the Roslin Institute, in which bee venom and acetic acid was injected into the lips of rainbow trout, resulted in fish rubbing their lips along the sides and floors of their tanks, which the researchers believe was an effort to relieve themselves of pain. One researcher argues about the definition of pain used in the studies.
In 2003, Scottish scientists at the University of Edinburgh performing research on rainbow trout concluded that fish exhibit behaviors often associated with pain, and the brains of fish fire neurons in the same way human brains do when experiencing pain. Professor James D. Rose of the University of Wyoming criticized the study, claiming it was flawed, mainly since it did not provide proof that fish possess "conscious awareness, particularly a kind of awareness that is meaningfully like ours". Rose argues that, since the fish brain is different from ours, fish are probably not conscious in the manner humans are, and while fish may react in a way similar to the way humans react to pain, the reactions in the case of fish have other causes. Rose had published his own opinion a year earlier arguing that fish cannot feel pain because they lack the appropriate neocortex
in the brain. Studies indicating that fish can feel pain were confusing nociception
(responding to threatening stimulus) with feeling pain, says Rose. "Pain is predicated on awareness. The key issue is the distinction between nociception and pain. A person who is anaesthetised in an operating theatre will still respond physically to an external stimulus, but he or she will not feel pain." However, animal behaviourist Temple Grandin
argues that fish could still have consciousness without a neocortex because "different species can use different brain structures and systems to handle the same functions."
In a 2009 paper, Janicke Nordgreen from the Norwegian School of Veterinary Science
, Joseph Garner from Purdue University
, and others, published research which concluded that goldfish do feel pain, and that their reactions to pain are much like those of humans. "There has been an effort by some to argue that a fish's response to a noxious stimulus is merely a reflexive action, but that it didn't really feel pain," Garner said. "We wanted to see if fish responded to potentially painful stimuli in a reflexive way or a more clever way." The fish were divided into two groups, one given morphine and the other saline. They were then subjected to unpleasant temperatures. The fish that were given saline subsequently acted with defensive behaviours, indicating anxiety, wariness and fear, whereas those given morphine did not. Nordgreen said that the behavioural differences they found showed that fish feel both reflexive and cognitive pain. "The experiment shows that fish do not only respond to painful stimuli with reflexes, but change their behavior also after the event," Nordgreen said. "Together with what we know from experiments carried out by other groups, this indicates that the fish consciously perceive the test situation as painful and switch to behaviors indicative of having been through an aversive experience."
Nociception
is the unconscious detection by the nervous system that damage is occurring somewhere. Nociceptors are sensory receptors that respond to potentially damaging stimuli by sending nerve signals to the spinal cord and brain. In 2003 Victoria Braithwaite was able to demonstrate the presence of nociceptors on the face and snout of the trout. The receptors responded to touch, heat and chemical stimulation by sending an electrical signal through the trigeminal nerve to the brain.
The Norwegian Research Council is funding a three-year research project, scheduled to end in December 2011, into whether cod
can feel pain. The researchers will use fMRI and EEG
s to study how the cod brain works. The aim of the study is to identify the parts of the cod brain that activate when cod are exposed to potentially painful stimuli, and how those signals are processed.
Zebrafish, native to the streams of the south eastern Himalayan
region, are commonly used as a model organism
in studies of vertebrate
development and gene function. Zebrafish are used to study development, toxicology and toxicopathology, because the body of a young zebrafish is nearly transparent, providing unique visual access to their internal anatomy. Another extensively used model organism is the medaka
, which is much sturdier than the traditional zebrafish. Medakas are easy to rear in the laboratory because of their prolific reproduction rates and short generation times. The short-lived ram cichlid
is also used in laboratory studies because of its ease of breeding and predictable pattern of ageing. Stickleback
s have traditionally been used as model organism in the study of fish behaviour.
The extent to which animal research
causes pain to laboratory animals is the subject of much debate. Marian Stamp Dawkins
defines "suffering" in laboratory animals as the experience of one of "a wide range of extremely unpleasant subjective (mental) states." The United States Department of Agriculture
defines a "painful procedure" in an animal study as one that would "reasonably be expected to cause more than slight or momentary pain or distress in a human being to which that procedure was applied."
Animal protection advocates have raised concerns about the possible suffering
Suffering
Suffering, or pain in a broad sense, is an individual's basic affective experience of unpleasantness and aversion associated with harm or threat of harm. Suffering may be qualified as physical or mental. It may come in all degrees of intensity, from mild to intolerable. Factors of duration and...
of fish caused by angling
Angling
Angling is a method of fishing by means of an "angle" . The hook is usually attached to a fishing line and the line is often attached to a fishing rod. Fishing rods are usually fitted with a fishing reel that functions as a mechanism for storing, retrieving and paying out the line. The hook itself...
. In light of recent research, some countries, like Germany, have banned specific types of fishing, and the RSPCA (which has authority in England and Wales) now formally prosecutes individuals who are cruel to fish.
Background
The idea that animals might not feel painPain
Pain is an unpleasant sensation often caused by intense or damaging stimuli such as stubbing a toe, burning a finger, putting iodine on a cut, and bumping the "funny bone."...
as human beings feel it traces back to the 17th-century French philosopher, René Descartes
René Descartes
René Descartes ; was a French philosopher and writer who spent most of his adult life in the Dutch Republic. He has been dubbed the 'Father of Modern Philosophy', and much subsequent Western philosophy is a response to his writings, which are studied closely to this day...
, who argued that animals do not experience pain and suffering, because they lack consciousness
Consciousness
Consciousness is a term that refers to the relationship between the mind and the world with which it interacts. It has been defined as: subjectivity, awareness, the ability to experience or to feel, wakefulness, having a sense of selfhood, and the executive control system of the mind...
. Bernard Rollin
Bernard Rollin
Bernard E. Rollin is an American philosopher who specializes in animal rights and animal consciousness. He is a professor of philosophy, animal sciences, and biomedical sciences at Colorado State University....
of Colorado State University, the principal author of two U.S. federal laws regulating pain relief for animals, writes that researchers remained unsure into the 1980s as to whether animals experience pain, and veterinarians trained in the U.S. before 1989 were simply taught to ignore animal pain. In his interactions with scientists and other veterinarians, Rollin was regularly asked to "prove" that animals are conscious, and to provide "scientifically acceptable" grounds for claiming that they feel pain. Carbone writes that the view that animals feel pain differently is now a minority one. Academic reviews of the topic are more equivocal, noting that although the argument that animals have at least simple conscious thoughts and feelings has strong support; some critics continue to question how reliably animal mental states can be determined.
Veterinary medicine uses, for actual or potential animal pain, the same analgesics and anesthetics used in humans.
Behaviour
Experiments by William Tavolga provide evidence that fish have pain and fear responses. For instance, in Tavolga’s experiments, toadfish grunted when electrically shocked, and over time they came to grunt at the mere sight of an electrode.Additional tests conducted at both the University of Edinburgh and the Roslin Institute, in which bee venom and acetic acid was injected into the lips of rainbow trout, resulted in fish rubbing their lips along the sides and floors of their tanks, which the researchers believe was an effort to relieve themselves of pain. One researcher argues about the definition of pain used in the studies.
In 2003, Scottish scientists at the University of Edinburgh performing research on rainbow trout concluded that fish exhibit behaviors often associated with pain, and the brains of fish fire neurons in the same way human brains do when experiencing pain. Professor James D. Rose of the University of Wyoming criticized the study, claiming it was flawed, mainly since it did not provide proof that fish possess "conscious awareness, particularly a kind of awareness that is meaningfully like ours". Rose argues that, since the fish brain is different from ours, fish are probably not conscious in the manner humans are, and while fish may react in a way similar to the way humans react to pain, the reactions in the case of fish have other causes. Rose had published his own opinion a year earlier arguing that fish cannot feel pain because they lack the appropriate neocortex
Neocortex
The neocortex , also called the neopallium and isocortex , is a part of the brain of mammals. It is the outer layer of the cerebral hemispheres, and made up of six layers, labelled I to VI...
in the brain. Studies indicating that fish can feel pain were confusing nociception
Nociception
Nociception is defined as "the neural processes of encoding and processing noxious stimuli." It is the afferent activity produced in the peripheral and central nervous system by stimuli that have the potential to damage tissue...
(responding to threatening stimulus) with feeling pain, says Rose. "Pain is predicated on awareness. The key issue is the distinction between nociception and pain. A person who is anaesthetised in an operating theatre will still respond physically to an external stimulus, but he or she will not feel pain." However, animal behaviourist Temple Grandin
Temple Grandin
Temple Grandin is an American doctor of animal science and professor at Colorado State University, bestselling author, and consultant to the livestock industry on animal behavior...
argues that fish could still have consciousness without a neocortex because "different species can use different brain structures and systems to handle the same functions."
In a 2009 paper, Janicke Nordgreen from the Norwegian School of Veterinary Science
Norwegian School of Veterinary Science
Norwegian School of Veterinary Science or NVH is a public university located at Adamstuen in Oslo, that educates veterinarians and veterinary nurses as well as research within aquatic medicine, food safety, comparative medicine and mammalian diseases, health and welfare. The institution has about...
, Joseph Garner from Purdue University
Purdue University
Purdue University, located in West Lafayette, Indiana, U.S., is the flagship university of the six-campus Purdue University system. Purdue was founded on May 6, 1869, as a land-grant university when the Indiana General Assembly, taking advantage of the Morrill Act, accepted a donation of land and...
, and others, published research which concluded that goldfish do feel pain, and that their reactions to pain are much like those of humans. "There has been an effort by some to argue that a fish's response to a noxious stimulus is merely a reflexive action, but that it didn't really feel pain," Garner said. "We wanted to see if fish responded to potentially painful stimuli in a reflexive way or a more clever way." The fish were divided into two groups, one given morphine and the other saline. They were then subjected to unpleasant temperatures. The fish that were given saline subsequently acted with defensive behaviours, indicating anxiety, wariness and fear, whereas those given morphine did not. Nordgreen said that the behavioural differences they found showed that fish feel both reflexive and cognitive pain. "The experiment shows that fish do not only respond to painful stimuli with reflexes, but change their behavior also after the event," Nordgreen said. "Together with what we know from experiments carried out by other groups, this indicates that the fish consciously perceive the test situation as painful and switch to behaviors indicative of having been through an aversive experience."
Anatomy
Nociception
Nociception is defined as "the neural processes of encoding and processing noxious stimuli." It is the afferent activity produced in the peripheral and central nervous system by stimuli that have the potential to damage tissue...
is the unconscious detection by the nervous system that damage is occurring somewhere. Nociceptors are sensory receptors that respond to potentially damaging stimuli by sending nerve signals to the spinal cord and brain. In 2003 Victoria Braithwaite was able to demonstrate the presence of nociceptors on the face and snout of the trout. The receptors responded to touch, heat and chemical stimulation by sending an electrical signal through the trigeminal nerve to the brain.
The Norwegian Research Council is funding a three-year research project, scheduled to end in December 2011, into whether cod
Cod
Cod is the common name for genus Gadus, belonging to the family Gadidae, and is also used in the common name for various other fishes. Cod is a popular food with a mild flavor, low fat content and a dense, flaky white flesh. Cod livers are processed to make cod liver oil, an important source of...
can feel pain. The researchers will use fMRI and EEG
EEG
EEG commonly refers to electroencephalography, a measurement of the electrical activity of the brain.EEG may also refer to:* Emperor Entertainment Group, a Hong Kong-based entertainment company...
s to study how the cod brain works. The aim of the study is to identify the parts of the cod brain that activate when cod are exposed to potentially painful stimuli, and how those signals are processed.
Laboratory fish
Himalayas
The Himalaya Range or Himalaya Mountains Sanskrit: Devanagari: हिमालय, literally "abode of snow"), usually called the Himalayas or Himalaya for short, is a mountain range in Asia, separating the Indian subcontinent from the Tibetan Plateau...
region, are commonly used as a model organism
Model organism
A model organism is a non-human species that is extensively studied to understand particular biological phenomena, with the expectation that discoveries made in the organism model will provide insight into the workings of other organisms. Model organisms are in vivo models and are widely used to...
in studies of vertebrate
Vertebrate
Vertebrates are animals that are members of the subphylum Vertebrata . Vertebrates are the largest group of chordates, with currently about 58,000 species described. Vertebrates include the jawless fishes, bony fishes, sharks and rays, amphibians, reptiles, mammals, and birds...
development and gene function. Zebrafish are used to study development, toxicology and toxicopathology, because the body of a young zebrafish is nearly transparent, providing unique visual access to their internal anatomy. Another extensively used model organism is the medaka
Oryzias latipes
Oryzias latipes, also known as Medaka and Japanese killifish, is a member of genus Oryzias , the only genus in the subfamily Oryziinae. This rather small...
, which is much sturdier than the traditional zebrafish. Medakas are easy to rear in the laboratory because of their prolific reproduction rates and short generation times. The short-lived ram cichlid
Ram cichlid
Mikrogeophagus ramirezi is a species of freshwater fish endemic to the Orinoco River basin, in the savannahs of Venezuela and Colombia in South America...
is also used in laboratory studies because of its ease of breeding and predictable pattern of ageing. Stickleback
Stickleback
The Gasterosteidae are a family of fish including the sticklebacks. FishBase currently recognises sixteen species in the family, grouped in five genera. However several of the species have a number of recognised subspecies, and the taxonomy of the family is thought to be in need of revision...
s have traditionally been used as model organism in the study of fish behaviour.
The extent to which animal research
Animal testing
Animal testing, also known as animal experimentation, animal research, and in vivo testing, is the use of non-human animals in experiments. Worldwide it is estimated that the number of vertebrate animals—from zebrafish to non-human primates—ranges from the tens of millions to more than 100 million...
causes pain to laboratory animals is the subject of much debate. Marian Stamp Dawkins
Marian Stamp Dawkins
Marian Ellina Stamp Dawkins is professor for animal behaviour at the University of Oxford, where she heads the Animal Behaviour Research Group. She has published several books, one of which has been translated into German, and many peer-reviewed papers. She is considered an expert in animal welfare...
defines "suffering" in laboratory animals as the experience of one of "a wide range of extremely unpleasant subjective (mental) states." The United States Department of Agriculture
United States Department of Agriculture
The United States Department of Agriculture is the United States federal executive department responsible for developing and executing U.S. federal government policy on farming, agriculture, and food...
defines a "painful procedure" in an animal study as one that would "reasonably be expected to cause more than slight or momentary pain or distress in a human being to which that procedure was applied."
See also
- Animal cognitionAnimal cognitionAnimal cognition is the title given to the study of the mental capacities of non-human animals. It has developed out of comparative psychology, but has also been strongly influenced by the approach of ethology, behavioral ecology, and evolutionary psychology...
- Emotion in animalsEmotion in animalsThere is no scientific consensus on emotion in animals, that is, what emotions certain species of animals, including humans, feel. The debate concerns primarily mammals and birds, although emotions have also been postulated for other vertebrates and even for some invertebrates.Animal lovers,...
- Moral status of animals in the ancient worldMoral status of animals in the ancient worldThe 21st-century debates about animal welfare and animal rights can be traced back to the ancient world. The idea that the use of animals by humans—for food, clothing, entertainment, and as research subjects—is morally acceptable, springs mainly from two sources.First, there is the idea...
- Pain in crustaceansPain in crustaceansThe question of whether or not crustaceans can experience pain is unresolved. Because of the ambiguous nature of pain, most people who contend that crustaceans do have this capacity approach the issue using 'argument by analogy' – that is, they hold that certain similarities between crustacean and...
- Pain in invertebratesPain in invertebratesPain in invertebrates is a problematic issue. Although there are numerous definitions of pain, almost all involve two key components. First, nociception is required. This is the ability to detect noxious stimuli which evokes a reflex response that moves the entire animal, or the affected part of...
- Pain and suffering in laboratory animals
- SentienceSentienceSentience is the ability to feel, perceive or be conscious, or to have subjective experiences. Eighteenth century philosophers used the concept to distinguish the ability to think from the ability to feel . In modern western philosophy, sentience is the ability to have sensations or experiences...
Further references
- Braithwaite, VA (2010) Do Fish Feel Pain? Oxford University Press. ISBN 9780199551200
- Braithwaite VA and Boulcott P (2007) "Pain perception, aversion and fear in fish" Diseases of aquatic organisms, 75(2): 131-138. Download
- Chandroo K, Yue S, and Moccia R (2004) "An evaluation of current perspectives on consciousness and pain in fishes" Fish and Fisheries, 5(4): 281-295. Download
- Grandin, Temple and Deesing, Mark (2003 update) Distress in Animals: Is it Fear, Pain or Physical Stress? American Board of Veterinary Practitioners - Symposium 2002.
- Henriksen S, Vaagland H, Sundt-Hansen L, May R and Fjellheim A (2003) "Consequences of pain perception in fish for catch and release, aquaculture and commercial fisheries" Kurs i dyreforsøkslære ZO 8091, Høsten .
- Roquesa JAC, Abbinka W, Geurdsb F, van de Visa H and Flik G (2010) "Tailfin clipping, a painful procedure: Studies on Nile tilapia and common carp" Physiology & Behavior, 101 (4): 533–540.
- Rose JD Do fish feel pain. Undated essay, University of Wyoming.
- Schultz, Nora (2007) "When fish get emotional" New Scientist.
- Smith JLB, Smith MM and Heemstra PC (2003) Smiths' Sea fishes Page 9–10, Struik. ISBN 9781868728909. – a classic angler's argument that fish do not feel pain.
- Sneddon LU How important is pain to a fish? Undated essay, University of Liverpool
- Sneddon LU (2003) The evidence for pain in fish: the use of morphine as an analgesic Applied Animal Behaviour Science, 83(2):153-162.
External links
- Scientists Tip the Scales Against Anglers Der Spiegel, November 2011.