Innate immunity of fish (overview).

Fish welfare: Current issues in aquaculture

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 we igh the concern for welfare of fish against the hum an interests involved, but ethical frameworks exist th at suggest how this might be approached. Different definitions of animal welfare focus on an animal's condition, on its subjective experience o f that condition and/or on whether it can lead a natu ral life. These provide different, legitimate, pers pectives, but the approach taken in this paper is to focus on welfare as the absence of suffering. An unresolved and controversial issue in discussion s about animal welfare is whether non-human animals exposed to adverse experiences such as physical injury or confinement experience what humans would call suffering. The neocortex, which in huma ns is an important part of the neural mechanism tha t generates the subjective experience of suffering, i s lacking in fish and non-mammalian animals, and it has been argued that its absence in fish indicates that fish cannot suffer. However, a strong alternative view is that complex animals with sophisticated behaviour, such as fish, probably have the capacity for suffer ing, though this may be different in degree and kind fro m the human experience of this state. Recent empirical studies support this view and show that painful stimuli are, at least, strongly avers ive to fish. Consequently, injury or experience of othe r harmful conditions is a cause for concern in term s of welfare of individual fish. There is also growing e vidence that fish can experience fear-like states a nd that they avoid situations in which they have experience d adverse conditions.

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Current issues in fish welfare

Stress is an event that most animals experience and that induces a number of responses involving all three regulatory systems, neural, endocrine and immune. When the stressor is acute and short-term, the response pattern is stimulatory and the fish immune response shows an activating phase that specially enhances innate responses. If the stressor is chronic the immune response shows suppressive effects and therefore the chances of an infection may be enhanced. In addition, coping with the stressor imposes an allostatic cost that may interfere with the needs of the immune response. In this paper the mechanisms behind these immunoregulatory changes are reviewed and the role of the main neuroendocrine mechanisms directly affecting the building of the immune response and their consequences are considered.

Stress and immune modulation in fish.

Exploration of the hypothalamic–pituitary–adrenal function as a tool to evaluate animal welfare

High stocking density has been shown to produce a wide variety of effects on cultured fish populations, such as alterations in behavior and poor feed utilization, resulting in mortality and poor growth. High stocking density has also been reported to produce chronic stress and mobilization of energy sources in fish. There are few studies focusing on the effect of high stocking density on one of the most important marine fish species for Mediterranean aquaculture, gilthead seabream (Sparus aurata). Consequently, this study investigates the effect of high stocking density on juveniles of this species, focusing on effects of stocking density on growth, biochemical composition, immune status and hematology.

High stocking density produces crowding stress altering some physiological and biochemical parameters in gilthead seabream, Sparus aurata, juveniles

Effect of vitamin E and C dietary supplementation on some immune parameters of gilthead seabream (Sparus aurata) juveniles subjected to crowding stress

J.M. Vergara

Papers

High stocking density produces crowding stress altering some physiological and biochemical parameters in gilthead seabream, Sparus aurata, juveniles

Effect of vitamin E and C dietary supplementation on some immune parameters of gilthead seabream (Sparus aurata) juveniles subjected to crowding stress

Protein sparing effect of lipids in diets for fingerlings of gilthead sea bream [Sparus aurata]

Low vitamin E in diet reduces stress resistance of gilthead seabream (Sparus aurata) juveniles.

Growth, feed utilization and body lipid content of gilthead seabream (Sparus aurata) fed increasing lipid levels and fish meals of different quality