Current issues in fish welfare

Abstract

Human beings may affect the welfare of fish through fisheries, aquaculture and a number of other activities. There is no agreement on just how to weigh the concern for welfare of fish against the human interests involved, but ethical frameworks exist that suggest how this might be approached.Different definitions of animal welfare focus on an animal's condition, on its subjective experience of that condition and/or on whether it can lead a natural life. These provide different, legitimate, perspectives, but the approach taken in this paper is to focus on welfare as the absence of suffering.An unresolved and controversial issue in discussions about animal welfare is whether nonhuman animals exposed to adverse experiences such as physical injury or confinement experience what humans would call suffering. The neocortex, which in humans is an important part of the neural mechanism that generates the subjective experience of suffering, is lacking in fish and non-mammalian animals, and it has been argued that its absence in fish indicates that fish cannot suffer. A strong alternative view, however, is that complex animals with sophisticated behaviour, such as fish, probably have the capacity for suffering, though this may be different in degree and kind from the human experience of this state.Recent empirical studies support this view and show that painful stimuli are, at least, strongly aversive to fish. Consequently, injury or experience of other harmful conditions is a cause for concern in terms of welfare of individual fish. There is also growing evidence that fish can experience fear-like states and that they avoid situations in which they have experienced adverse conditions. Human activities that potentially compromise fish welfare include anthropogenic changes to the environment, commercial fisheries, recreational angling, aquaculture, ornamental fish keeping and scientific research. The resulting harm to fish welfare is a cost that must be minimized and weighed against the benefits of the activity concerned.Wild fish naturally experience a variety of adverse conditions, from attack by predators or conspecifics to starvation or exposure to poor environmental conditions. This does not make it acceptable for humans to impose such conditions on fish, but it does suggest that fish will have †Author to whom correspondence should be addressed. Tel.: þ 44 (0) 141 330 5975; fax: þ 44 (0) 330 5971;

Melanin-based skin spots reflect stress responsiveness in salmonid fish

“…It is therefore of interest to investigate whether increased melanism in salmon is associated with reduced ectoparasite prevalence and fecundity, as has already been reported in birds (Roulin et al 2003(Roulin et al , 2001). Identification and concomitant selection for more stress-resistant individuals in aquaculture could also potentially alleviate other critical industry issues related to disease, welfare and sustainability of feed resources (Fevolden, 1992;Huntingford et al, 2006;Small et al, 2008). For instance, one study reported reduced feed waste from LR as compared to HR rainbow trout rearing units, along with improved feed conversion ratios in LR fish (Øverli et al 2006b).…”

Anaesthesia and handling stress effects on pigmentation and monoamines in Arctic charr

“…Fish are relatively new in farming industry compared to terrestrial animals and plants, and intensive fish farming just started during the last century (Duarte et al 2007). Welfare is an important issue within aquaculture and relates to stress coping styles (Huntingford et al 2006). For instance, selection of fast-growing fish might lead to more aggressive and risk-taking fish (i.e.…”

<b>Psychological Stress and Welfare in Fish</b>

“…A number of different fish behavioural patterns have been related to this defensive system (Huntingford et al, 2006;Ashley & Sneddon, 2008). In response to a threatening event, they may include protective motor reactions like flee, hide or shoaling.…”

“…Body rocking and rubbing against surfaces were described as nociceptive and pain responses (Sneddon et al, 2003a). Locomotory patterns are also sensitive to many stressors, and much used in behavioural analysis (Huntingford et al, 2006). A number of environmental factors, like exposure to noxious chemicals, water temperature, etc., may affect the effectiveness of the fight-orflight response (Schreck et al, 1997).…”

“…Schreck et al, 1997;Conte, 2004;Huntingford et al, 2006). The relevance of a stressor to an individual has not only to do with its nature, but also with the pattern of exposure (Broom & Johnson, 1993).…”