FISH WELFARE LITERATURE REVIEW

Pottinger, T.G.. 1995 FISH WELFARE LITERATURE REVIEW. Institute of Freshwater Ecology, 82pp.

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Abstract/Summary

i. SUMMARY This study sought to identify, summarise, and interpret published research which has addressed three areas of concern to the angling community: (a) Physiological stress. Prolonged activation of the physiological stress response can have harmful effects in animals. Do the procedures associated with the capture of fish by angling; hooking, playing, landing, unhooking, confinement within keepnets, weighing, cause a stress response? If so, is the response severe enough to cause concern regarding the welfare of the fish? (b) Physical damage. Do the processes associated with the capture of fish cause damage that might affect the subsequent welfare and survival of the fish? (c) Pain. It has been suggested that hooked fish experience pain during capture and unhooking. Is there evidence that fish can experience "pain and suffering" in a manner analogous to higher vertebrates? The main points highlighted by the literature review are summarised below. 1. The physiological stress associated with capture 1.1 - Capture by angling is always accompanied by physiological disturbances typical of activation of the hypothalamic-pituitary-interrenal axis. Capture by angling may therefore be considered to cause physiological stress in fish. 1.2 - Physiological recovery is complete within 24 - 72 h of capture. The stress associated with capture may be considered acute, rather than chronic, and unlikely to have long-term impact on the well-being of the fish. 1.3 - Mortality of fish within 72 h of capture is rare. 1.4 - Water temperature may be a significant factor in determining the severity of the stress response to capture. 1.5 - The stress of capture may be more severe for larger fish. 1.6 - There is an overwhelming requirement for well-designed studies to examine the physiological effect of capture, and time-course of recovery following capture, in non-salmonid European fish. Such studies should encompass an examination of the effect of water temperature, fish size and delayed release. 2. The respiratory and metabolic effects of capture by angling 2.1 - Even when exposed to an exercise regime arguably more severe than that imposed by rod and line capture, the available data suggest that most species of fish recover baseline respiratory and metabolic levels within 8 - 24 h. 2.2 - Fish size and water temperature both affect the severity and duration of the metabolic and respiratory effects of severe exercise. 2.3 - Severe exercise can, under certain circumstances, cause mortality in fish. Whether this arises under experimental conditions because of the imposition of unrealistically extreme levels of activity, or because of the use of "unfit" fish is not clear. 3. The impact of capture stress on post-release behaviour 3.1 - Capture by angling is likely to result in some short-term modification of behaviour. In prey fish, this may result in an increased susceptibility to predation. 3.2 - The duration of behavioural modification following stress is shorter than the period required for physiological recovery from stress. 3.3 - There is no research in this area that has examined species native to the UK. 4. Physical damage associated with capture 4.1 - There is a measurable level of mortality associated with hooking of fish. Most studies have not monitored survival beyond 72 h following capture. 4.2 - Mortality is low to negligible in fish that are hooked in the jaw, but can be extremely high in fish hooked in the throat, gills and deep-hooked in the gut. The majority of fish caught under experimental conditions were hooked in the jaw. 4.3 - There may be differences in mortality rate associated with natural and artificial baits and with hook size and type. The species and size of fish may also be factors. There are too few data available at present to draw firm conclusions. 4.4 - Almost all the data available on hooking mortality originate from North America. The species studied are almost exclusively predators, captured with either lures or bait. Although this information may be applicable to some species of fish native to the UK (perch, pike, zander, salmonids), there are no data in the literature derived from studies on cyprinid fish that constitute the majority of species sought by freshwater anglers in the UK. 5. Pain perception in fish 5.1 - It is advantageous for an animal to be aware of damage to its body and to be able to avoid potentially damaging situations. A system that alerts the animal to damage has survival value. 5.2 - Several of the anatomical and biochemical components involved in pain perception in mammals are present in fish. However, some key elements (e.g. unmyelinated nerve fibres) are absent from certain species and other elements (e.g. the forebrain/cerebral cortex) are considerably less well developed in fish than in mammals. 5.3 - The neurophysiological mechanisms underlying pain perception in man and other mammals are complex and not fully understood. Many components of the nociceptive/pain perception system have other, unrelated, functions. Identification of such components in fish cannot be considered proof that fish experience "pain". 5.4 - It is the opinion of experts in the field that animals may possess mechanisms allowing them to avoid damage and facilitate recuperation without conscious perception of pain, in human terms. 5.5 - Our understanding of pain perception in fish is hampered by the lack of research on this subject, and by the difficulties inherent in interpreting the behavioural and physiological responses of an animal taxonomically far removed from mammals. 5.6 - There is no information available in the literature at present which provides firm evidence that fish perceive pain as mammals apparently do or, conversely, that they cannot perceive pain as mammals do. On balance, it seems unlikely that fish experience pain as understood by humans. However, the problem of assessing exactly what a fish perceives when exposed to stimuli considered to be noxious or unpleasant in human terms may prove to be intractable.

Item Type:	Publication - Report
Programmes:	Other/Admin
UKCEH and CEH Sections/Science Areas:	_ Pre-2000 sections
Funders/Sponsors:	Angling Governing Bodies Liaison Group, British Field Sports Society
Additional Keywords:	fish, angling, fishing, stress, welfare, catch-and-release, pain perception, review
NORA Subject Terms:	Zoology Biology and Microbiology Ecology and Environment
Date made live:	22 Jul 2009 13:21 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/7223

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