Section 1: Introduction to welfare in commercial fishing

3 Fish are sentient beings

Pain and fear in fish

“Anatomical, pharmacological and behavioural data suggest that affective states of pain, fear and stress are likely to be experienced by fish in similar ways as in tetrapods [amphibians, reptiles, birds and mammals]” (Chandroo et al, 2004a)

Credit: National Oceanic and Atmospheric Administration/Department of Commerce. Photographer: Mr. Mohammed Al Momany, Aqaba, Jordan

Professor John Webster, of the University of and that Bristol, defines sentience with (2009): “Responses of fish, of some species and under ”A sentient animal is one for whom feelings certain situations, suggest that they are able to matter”. experience fear”.

Sentience is about the inner life of an animal, and Fish sentience is central to the case for more a sentient animal has capacity to suffer fear, pain humane treatment of fish in commercial fishing, or distress as well as a sense of well-being. and is therefore discussed in this chapter. Evidence that fish are sentient has been sufficient to achieve international recognition that their The Medway Report welfare matters. The policy statement of the World 1980 saw the publication of the “Medway report” Organisation for Animal Health (OIE) states (OIE, (Medway, 1980) commissioned by the RSPCA to 2008b): enquire whether practices related to shooting and

“The use of fish carries with it an ethical angling in the UK involved cruelty (defined as responsibility to ensure the welfare of such “unnecessary suffering”). As part of its animals to the greatest extent practicable.” investigation, the panel of inquiry considered the evidence that fish feel pain. They point out that In the European Union, a scientific panel ability to feel pain is generally useful to an animal, commissioned by the EU Commission adopted its helping to prevent injury and unhelpful movement “General approach to fish welfare and to the during recovery. They quote the report of the concept of sentience in fish” in 2009 (AHAW, Committee on Cruelty to Wild Animals, 1951: 2009). Having examined the research carried out for some species of fish (a relatively small number “Pain is of the utmost biological value to of species have been studied), this panel animals because, in general, what is painful is concludes: also harmful, and consequently animals tend to avoid anything which gives them the sensation “The balance of the evidence indicates that of pain. Pain is the “conditioning” stimulus some fish species have the capacity to which teaches an animal to avoid anything experience pain” which is physically harmful to it, and this end could hardly be achieved unless the pain felt

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by an animal were painful in the ordinary sense. Pain is therefore a sensation of clear- cut biological usefulness...”

The Medway Report discusses the neurological and pharmacological evidence that fish can feel pain. The pain receptors present in the skin of man, called “nociceptors”, have been found in other including fish. So too has “substance P”, a chemical “apparently important in the transmission of pain”. The Medway report published data on levels of substance P and enkephalin found in the trout brain, which were Social intelligence in fish “of the same order as in a mammal”. Enkephalins are endogenous opiates, i.e. painkillers similar to Fish are “steeped in social intelligence, pursuing morphine in their effect, produced in the body and Machiavellian strategies of manipulation, punishment “it has been suggested to us that they may play a and reconciliation, exhibiting stable cultural traditions, role in the process of through and co-operating to inspect predators and catch gratification”. The report also refers to food” (Laland et al, 2003). benzodiazepines, which “apparently play a role in Credit: National Oceanic and Atmospheric Administration/Department of the pharmacology of anxiety in man” and which Commerce. Photographer: Farb Monitor Expedition have also been found in a range of other vertebrates including 3 bony fish (, plaice and fish species: eel). “form mental representations of their environment and use these for quite complex The Medway Report concluded that: feats of navigation”

“In the light of evidence reviewed … it is and a collection of articles on fish learning was recommended that, where considerations of published in a special edition of “Fish and welfare are involved, all animals fisheries” (Laland et al, 2003) in which the (i.e., mammals, birds, reptiles, amphibians and introductory chapter states that fish are: fish) should be regarded as equally capable of suffering to some degree or another, without “steeped in social intelligence, pursuing distinction between ‘warm-blooded’ and ‘cold Machiavellian strategies of manipulation, blooded’ members.” punishment and reconciliation, exhibiting stable cultural traditions, and co-operating to Researching fish sentience inspect predators and catch food”. In the last 20 years, animal welfare science has developed into a scientific field in its own right, The BBC news website reported this (BBC News, and the evidence for fish sentience has grown. 2003b) saying that, according to scientists, fish

Because cannot be “do not deserve their reputation as the dim- measured directly, animal welfare scientists look wits of the animal kingdom”. for anatomical, physiological and behavioural Also reported in the news (Mail Online, 2008), evidence as indicators of sentience or suffering. have been the learning achievements of a Fish intelligence has also been studied and, for called “Comet”. Comet has been trained example, it is known (FSBI, 2002) that some

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Section 1: Introduction to fish welfare in commercial fishing

by his owner Dr Dean Pomerleau to perform a Following a request from the European number of tricks for food rewards, and a video clip Commission, the AHAW Panel was asked to of this can be viewed on the internet at deliver a Scientific Opinion on the animal welfare fishcount.org.uk/fish-sentience. The video shows, aspects of . The AHAW panel for example, Comet fetch hoops “just like dogs reviewed the current evidence for pain and fear in do”. fish, which it presented in the above-mentioned “General approach to fish welfare and to the Of key importance in animal welfare is the capacity concept of sentience in fish” (AHAW, 2009). This to experience pain, fear and distress. Professor evidence is outlined below following a brief Donald Broom, of the University of Cambridge, discussion of the arguments made against fish sums up the case for fish feeling pain (1999a): sentience.

“There are some differences in sensory Critics of fish sentience functioning between fish and mammals Some people argue that fish are not sentient and because fish live in water but the pain system take a Cartesian view of fish. Descartes (1596- of fish is very similar to that of birds and 1650) dissected conscious dogs without mammals. Fish have pain receptor cells, anaesthetic, after nailing them to boards, in order nociceptive neuronal pathways, specialized to demonstrate the circulation of blood (Magnotti, transmitter substances, electrophysiological 2006). This is perhaps not so dissimilar to the way responses to cuts, bruises and electric shocks, fish are treated in commercial fishing (for example, behavioural avoidance, learned avoidance of when they are dissected while conscious or places where they had unpleasant experiences impaled on hooks as live bait). Descartes argued and processing systems in the brain which that dogs, and other animals, do not feel pain or parallel those in birds and mammals. Hence at have feelings and are just machines. The dog’s least some aspects of pain as we know it must screams were just a mechanical response devoid be felt by fish.” of any feeling.

Fish feel pain Herring caught in the crush

Credit (above left): Courtesy of United Nations Food and Agriculture “at least some aspects of pain as we know it must be Organization. Photographer: Danilo Cedrone. National Oceanic and felt by fish” (Broom, 1999a) Atmospheric Administration/Department of Commerce.

Credit (above): National Oceanic and Atmospheric Administration/ Department of Commerce. Photographer: J. M. Olson.

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For some people, this Cartesian view is largely pain system which is based on an emotional response to their own perceptions of fish. For others this view is more • similar to that of other vertebrates (e.g. considered, and is presented as a scientific mammals and birds), and that argument. • involves these animals feeling pain,

While many people respect the welfare of these is discussed subsequently. animals, it is also true that many people empathise less with fish than they do with Fish have brain structures capable of mammals or birds. Fish have a particular “public feeling fear and pain relations” problem in that their physiological and AHAW (2009) discusses the similarities in brain behavioural responses to painful or distressing structure between fish and other vertebrates and events are not always obvious to human begins by saying that: observers. Fish lack the ability to make facial expressions and their vocalizations are more “As vertebrates, fish, birds and mammals limited (Yue, 2008). share a similar general brain structure”.

People may be inclined to believe that fish have Like that of other vertebrates, the fish brain less ability to feel pain because they may consists of the forebrain (i.e. telencephalon and consider them to be less intelligent than birds or diencephalon), midbrain and hindbrain. The fish mammals. Broom argues that there is no logical brain is not identical to the mammalian brain. It is reason to assume that greater cognitive ability smaller and fish do not have the extensive makes pain feel worse (Broom, 2001): cerebral cortex seen in the forebrain of mammals. This is a laminated structure which covers the “Pain might be a greater problem in animals telencephalon. with less cognitive ability”. It has sometimes been argued that because fish Is it not the case in humans, that young children do not possess this laminated structure (a seem all the more sensitive to pain, fear and “neocortex”), they must therefore be incapable of distress despite, or perhaps because, of the fact experiencing pain. However, there is good reason that they have less developed cognitive ability? to believe that fish do experience pain and fear As Professor John Webster of the University of without this particular structure. Bristol said (2005a) AHAW (2009) argues it is known that the same “you don’t have to be clever to suffer”. brain function can be served by different brain structures in different groups of animals, e.g. Some scientists have argued that fish cannot cognitive functions in birds and mammals (visual suffer. In 2002, Rose published a paper, stimuli are processed by part of the cerebral conducted at the behest of the American cortex in mammals but by the midbrain optic Fisheries Society, arguing that fish do not feel tectum in birds (FSBI, 2002)). Another example, pain because they do not have a neocortex and cited elsewhere, is that seen in dolphins, highly that their behaviours are reflexes without feeling intelligent animals whose brain is organized in a (Yue, 2008). fundamentally different way to that of primates (Marino 2002, cited in Chandroo et al, 2004b). It The evidence that fish do in fact have brain is also a matter of some debate whether human structures capable of feeling pain and fear is consciousness is a function of the neocortex discussed below. The evidence that fish have a

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Section 1: Introduction to fish welfare in commercial fishing

hippocampus is involved in memory and learning of spatial relationships. Damage to the Dm area in fish has been observed to impair the fear response without affecting spatial learning, and vice versa for damage to the Dl area.

Critics of fish sentience focus on the structural differences between the brain of fish and that of humans. Through convergent evolution, different species can develop the same function through anatomical structures that may be quite different. For example, there is good evidence that some invertebrates, such as decapod crustaceans (e.g. crabs and lobsters), have the capacity for pain and fear, despite the lack of a vertebrate pain system (Elwood et al, 2009; Broom, 2007). The invertebrates with the most complex brains are the (including and squid), which can solve maze puzzles and remember the solutions (Håstein et al, 2005). These authors also state that cephalopods appear to show Convergent evolution strong emotions that are signalled by profound changes in colour. In 1993, the UK legislation The brains of sentient animals can perform similar governing the use of animals in scientific research functions, without necessarily following the same was amended to include the common octopus design. (Elwood et al, 2009). An example of convergent evolution is seen in the dolphin brain, which is organised in a “fundamentally AHAW (2009) concludes its discussion on brain different pattern” to those of primates. Yet these animals structure by saying: have great cognitive abilities, seen elsewhere only in humans and great apes (Marino 2002, cited in “There is scientific evidence to support the Chandroo et al, 2004b). assumption that some fish species have brain Credit: OAR/National Undersea Research Program (NURP). structures potentially capable of experiencing Photographer: M. Herko. National Oceanic and Atmospheric Administration/ Department of Commerce. pain and fear”. alone, or restricted to any single area of the brain As Professor John Webster argues, since all or (Chandroo et al, 2004b). nearly all the evidence points in the direction of fish feeling pain (Webster, 2005b): As AHAW (2009) states, there is evidence that the fish forebrain contains within it several brain “The claim that fish ‘do not have the right sort structures that perform similar functions to those of brain’ to feel pain can no longer be called associated with pain and fear in higher scientific. It is just obstinate” vertebrates. These are known to be active after a noxious stimulus, such as pin-prick stimuli in trout and that (John Webster, personal communication, or goldfish. For example, the dorsomedial (Dm) 2009) and dorsolateral (Dl) telencephalon are thought to perform the same functions as the amygdala and “to say that a fish cannot feel pain because it hippocampus respectively in mammals. The doesn’t have a neocortex is like saying it amygdala is important in arousal and emotions, cannot breathe because it doesn’t have lungs”. particularly fear responses, while the

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Section 1: Introduction to fish welfare in commercial fishing

Fish probably experience pain, fear and primary response includes the release of stress in a similar way to other hormones e.g. cortisol. vertebrates Fish have a pain system similar to that of other In a number of studies referred to in this report, vertebrates. As stated by Chandroo et al (2004a): the measurement of physiological variables (such as cortisol) and adverse behaviour have shown “Anatomical, pharmacological and behavioural that fish suffer stress when caught (for example in data suggest that affective states of pain, fear gill nets (see 8.1 of chapter 8) and purse seine and stress are likely to be experienced by fish nets (see 7.1 of chapter 7), in fish traps and by in similar ways as in tetrapods [amphibians, hooks (see 13.1 of chapter 13)) and when reptiles, birds and mammals]”. subjected to live chilling (see chapter 17) and removal from water (see chapter 17). Fish have nociceptors (pain receptors) to detect harmful stimuli such as high temperatures or Implications of the evidence for fish harmful chemicals. These pain receptors connect, sentience via sensory pathways, to the brain. Activity in the brain has been measured when nociception (detection of harmful stimuli) occurs. The fact that the brain is involved during nociception “demonstrates the potential for pain perception in lower vertebrates [fish]” (Dunlop and Laming, 2005).

Painkillers, such as morphine work on fish. Fish, like other vertebrates, produce their own natural painkillers in the brain called “endogenous opioids”. The presence and action of painkillers in fish is further evidence that fish feel pain, or why would they need them? Fish are sentient beings Fish can learn to avoid noxious or threatening stimuli. For example paradise fish learned to The sentience of fish has huge ethical implications for the operate an escape hatch to avoid electric shocks. way they are caught and killed in fisheries.

Avoidance learning further suggests the Credit: OAR/National Undersea Research Program (NURP); University of North Carolina at Wilmington. Photographer: A. Hulbert. National Oceanic and behaviour is more than just a reflex. While Atmospheric Administration/Department of Commerce reflexes occur quickly, the detection of noxious stimuli in fish can cause profound and prolonged Most of what is known about human pain is from changes to the animal’s behaviour, lasting several self-reporting (Broom, 2001) and because a fish hours. Fish can also learn to avoid threatening, cannot report to us what it is feeling, it may be but not painful, stimuli suggesting they also feel that scientific method cannot prove, in an fear. absolute sense, that fish feel pain. Just as it

The evidence that fish can feel pain and fear is cannot be totally proven that babies, or even you given in more detail in 3.1 and 3.2 below. and I, can feel pain. The balance of evidence, Animal suffering is wider than pain and fear. together with what is understood about evolution AHAW (2009) reports that the stress physiology in and the biological purpose of pain, indicate that fish is “directly comparable to that of higher fish do feel pain and, for humane reasons, the vertebrates” and manifested as primary, benefit of any doubt should be given to avoiding secondary and tertiary stress responses. The suffering.

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Section 1: Introduction to fish welfare in commercial fishing

As this report goes to press, Dr. Victoria should be given to their welfare needs in 2 Braithwaite’s book “Do fish feel pain?” fisheries : (Braithwaite, 2010) brings the science behind the debate around into the open. She “In formulating and implementing the Union's agriculture, fisheries, transport, internal describes the many different pieces of evidence market, research and technological that together build up a picture of fish as animals development and space policies, the Union that, she concludes, “have the mental capacity to and the Member States shall, since animals feel pain”. She argues, on the basis of the are sentient beings, pay full regard to the evidence, that “I see no logical reason why we welfare requirements of animals, while should not extend to fish the same welfare respecting the legislative or administrative considerations that we currently extend to birds provisions and customs of the Member States and mammals”. relating in particular to religious rites, cultural traditions and regional heritage.” The sentience of fish has huge implications for the way they are treated in fisheries and 3.1 The evidence that fish feel pain elsewhere. Dr. Braithwaite (2010) identifies the in more detail welfare of fish caught in commercial fishing as a major fish welfare concern: The AHAW (2009) report lists some of the criteria used to indicate whether an animal, including fish, “In terms of sheer numbers of fish, the real might be capable of experiencing pain as follows. business is ocean-going trawlers scooping fish It goes on to give some examples of evidence from the sea. Fish, netted by the tens of supporting each of these in fish species: thousands, are pulled to the surface through such rapid changes in pressure that their swim (i) the existence of functional nociceptors bladders overinflate, causing the body to (ii) the presence and action of endogenous become severely distended. On reaching the opioids and opioid receptors, surface fish are dropped onto open decks (iii) the activation of brain structures involved in where they then flap around as they suffocate. pain processing, We tend not to think too hard about the way we (iv) the existence of pathways leading to higher capture fish at sea – it isn’t very pretty. We brain structures, wouldn’t accept killing chickens by throwing (v) the action of analgesics in reducing them into a tank of water and waiting for them nociceptive responses, to drown, so why don’t we object to fish (vi) the occurrence of avoidance learning, suffocating on trawler decks?” (vii) the suspension of normal behaviour associated with a noxious stimulus. Fish are also likely to suffer considerably when chased to exhaustion and buried in the crush of All of the above show a pain system in fish that is trawl nets; when snared in gill nets; when thrown similar to that of mammals. to tuna, or impaled on hooks, for use as live bait; and when gutted or frozen while still conscious. (i) the existence of functional nociceptors

Taking into account the great numbers of animals (pain receptors) involved, this is a huge animal welfare problem. Fish have pain receptors. Pain receptors are Action to address this problem is now required in called “nociceptors” because they detect noxious, the EU since the EU Treaty recognises animals i.e. harmful, things such as high temperatures or as sentient beings and states that full regard 2 The EU Treaty as amended by the Lisbon Treaty, Title II: Article 13 (CONSILIUM, 2008)

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Section 1: Introduction to fish welfare in commercial fishing

harmful chemicals. AHAW (2009) defines “nociception” as follows:

“Nociception is the detection of a noxious stimulus and is usually accompanied by a reflex withdrawal response away from that stimulus immediately upon detection. Noxious stimuli are those that can or potentially could cause tissue damage so stimuli such as high mechanical pressure, extremes of temperature and chemicals, such as acids, venoms, prostaglandins and so on, excite nociceptive

nerve fibres”. Fish have endogenous opioids As AHAW (2009) states, Sneddon and her team found nociceptors on the face of . Endogenous opioids are substances produced in the Elsewhere, Broom makes a more general point brain in order to reduce pain. “One has to ask why they (Broom, 2001) that: are needed in fish if these animals do not experience pain” (FSBI, 2002).

“most vertebrate animals which have been Credit: FreePixels.com investigated seem to have very similar pain receptors and associated central nervous enkephalins and endorphins, just as there pathways”. would be in humans”

As Broom explains, lampreys are one of the most and that (Ibid.): primitive vertebrates and modern (most species of fish alive today) have more in common “The distribution of enkephalins in the fish with humans than they do with lampreys. Primitive brain shows a similar pattern to that seen in as they are, lampreys too possess nociceptors. higher vertebrates”. Recordings were made from sensory neurones in the skin and mouth of lamprey during heavy FSBI (2002) reports the response of goldfish to pressure, puncture, pinching and burning and the analgesics (painkillers) is “similar to that of a rat” output was “like that which would be recorded in a and says of these endogenous painkillers: mammalian pain receptor”.

“one has to ask why they are needed in fish if (ii) the presence and action of these animals do not experience pain”. endogenous opioids and opioid receptors Endogenous opioids are substances produced in (iii) the activation of brain structures the brain in order to reduce pain. In mammals, these natural painkillers work through three involved in pain processing distinct types of opioid receptor, and these have The processing of pain in fish involves the brain. also been identified in zebrafish. Other evidence AHAW (2009) cites research by Dunlop and that fish produce these substances is given by the Laming which measured electrical activity in the fact that (AHAW, 2009): forebrain of trout and goldfish. Measurements in goldfish subjected to something noxious (e.g. heated prods) differed from those for harmless “When goldfish are subjected to stressful stimulation (e.g. being stoked with a paint brush) conditions, there is an elevation of pro- (Dunlop and Laming, 2005). Dunlop and Laming opiomelanocortin, the precursor of the argue that this research “demonstrates the

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Section 1: Introduction to fish welfare in commercial fishing

potential for pain perception in lower vertebrates (vi) the occurrence of avoidance learning [fish]”. There is evidence that fish can learn to avoid noxious stimuli, such as common and pike avoiding hooks in angling trials and goldfish that (iv) the existence of pathways leading to have learnt to avoid electric shocks. higher brain structures

The pain receptors of fish connect, via sensory Broom (2001) describes experiments in which pathways, to the brain. paradise fish were given an electric shock when

they entered a black compartment. They AHAW (2009) reports that in fish, as in other subsequently avoided the black compartment and vertebrates, information received by nociceptors learned to activate an escape hatch to avoid in the skin is relayed to the brain via two major further shocks. Avoidance learning has also been routes. Information from the head is sent via the documented for rainbow trout, as discussed in trigeminal tract, while information from the rest of 3.2. the body is sent via the spinothalamic tract. In fish, the trigeminal tract has been shown to project to the thalamus (part of the diencephalon (vii) the suspension of normal behaviour in the forebrain (FSBI, 2002)) as it does in other associated with a noxious stimulus vertebrates. It is sometimes argued by critics of fish sentience that, although fish can detect noxious (harmful) stimuli through nociceptors (pain receptors), that (v) the action of analgesics in reducing their response is a reflex behaviour without nociceptive responses feeling. AHAW (2009) argues that where a Analgesics (i.e. painkillers) work on fish, which noxious stimulus has adverse effects on an gives further evidence of a fish pain system animal’s normal behaviour beyond a simple similar to that of other vertebrates such as reflex, then this may indicate that the animal is mammals. Analgesics reduce the adverse perceiving pain, stating that: behaviour seen in response to noxious stimuli, and this indicates that a feeling of pain is “Reflex responses occur instantaneously and involved. within a few seconds but some of

the responses of fish may be prolonged to 3 to Some of the research by Sneddon et al into pain 6 hours (Sneddon, 2006)”. perception in rainbow trout is discussed in (vii) below. Rainbow trout that had been injected in AHAW (2009) goes on to describe research by the lips with acetic acid (a noxious substance) Sneddon et al to investigate the behavioural showed adverse behaviour. They were observed response of rainbow trout to noxious substances rubbing their lips on the substrate of the tank and (acetic acid and bee venom) injected into their displayed a rocking behaviour, as well as a faster lips. Changes in behaviour over a prolonged breathing rate. In a separate study, Sneddon et al period of time appeared to result from showed that when morphine was administered to experiencing pain: the fish, these effects were reduced.

“These fish showed an enhanced respiration AHAW (2009) goes on to cite research in which rate for approximately 3 hours, did not feed goldfish subjected to electric shocks show within this period, and showed anomalous agitated swimming, but if injected with morphine, behaviours such as rubbing of the affected the threshold for this response increased. area on the aquarium substratum and glass and rocking from side to side on either pectoral fin (Sneddon et al., 2003a; Sneddon et al., 2003b)“.

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In this research, fish injected with acid also failed movement, freezing and sinking in the water. In a to show their normal fear response to a novel number of studies these behaviours were shown challenge. As Yue (2008) explains, rainbow trout in response to conditioning, i.e. learnt. Learned are fearful of novel objects and try to keep a avoidance studies, as discussed in 3.1 above, distance from them, at least for a period of time. provide evidence that the displayed behaviour is The failure of these fish to avoid new objects not merely a reflex response. indicates that the painful stimulus dominated their attention. AHAW (2009) refers to a study of avoidance learning in rainbow trout. This study (Yue et al, A later study published after the AHAW panel’s 2004) showed that these fish can learn to avoid report, found that goldfish subjected to an threatening stimuli, indicating that they experience aversive, but non-harmful, heat were displaying fear. Rainbow trout were placed individually into a signs of fear 2 hours later (Nordgreen et al, 2009). tank comprising two chambers connected by a For the experiment, each fish was fitted with a doorway. When subjected to the frightening miniature jacket containing a tiny heater with an stimulus of a plunging dip net in the chamber upper limit of 50°C to prevent harm. The fish containing the fish, the fish escaped through the showed an escape response when the doorway to the other chamber. Each fish was temperature was raised to a certain level, at then presented with a neutral stimulus of a light which point the heat was turned off to prevent that went on 10s before the net plunged into the suffering. Half the fish were given morphine prior water. Over a 5-day period, all fish learned to to the heat tests. The Telegraph online (Dobson, avoid the plunging net by swimming through the 2009) reported this, quoting one of the doorway when the light was illuminated. All fish researchers Dr. James Garner of Purdue showed evidence of longer-term memory by University, Indiana: performing this response on the first occasion they were tested after 7 days of no testing. "Morphine had some effect on their behaviour in the test, but the major effect was this Learning is thought to involve receptors in the response two hours later. That was really brain that are activated by a substance called key…Those fish not given morphine showed NMDA. Chemicals that block these NMDA hovering behaviour and were less active. receptors (antagonists of NMDA receptors) have These are defence and fear behaviours. been shown to impair learning and fear

"We believe this hovering and inactivity are conditioning in mammals. Experiments have indicators of a general increase in fearfulness, shown that administering an NMDA receptor wariness, and a generalisation of a bad antagonist into the brain of a goldfish likewise experience. It is extremely difficult to explain impairs the ’ fear conditioning. this two hours later as a reflex”.

3.2 The evidence that fish feel fear

As discussed by AHAW (2009), fear, like pain, serves a function that is fundamental to survival in protecting animals against dangerous environmental threats.

Behavioural responses to potentially threatening stimuli that have been described for fish include escape responses, such as fast starts or erratic

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