12 - Stress Management and Welfare

Abstract

1. Introduction 1.1. Defining Welfare 2. Managing Stress in Fish 2.1. Considerations for Care of Wild Fish in Captivity 2.2. The Impact of Psychological Stress 2.3. Controlling and Preparing for Stress 3. The Impact of Stress on Fish Welfare 3.1. Stress in Fisheries 3.2. Stress in Aquaculture 3.3. Stress in Recreational Fishing 3.4. Stress in Ornamental Fish 3.5. Stress in Research Within a Laboratory Context 3.6. Stress and Welfare in Wild Fish 3.7. Surgery and Anesthesia 4. Conclusions and Future Directions Stress poses a significant challenge to the health and welfare of fish in a variety of contexts. Preserving fish well-being has obvious benefits for aquaculture, fisheries management practices, large-scale fisheries, recreational fishing, research, and the ornamental fish industry. Healthy fish provide better economic return, contribute to population size, provide experimentally sound data, are attractive and pleasing to watch, and pose no risk to public health. However, many practices in each of these areas where fish are used cause stress and as such may impair fish welfare. The impact of routine procedures that fish are subject to is discussed to better understand how stress can be managed in captivity. The means of reducing stress and its deleterious effects on fish behavior, development, growth, reproduction, and immune function are considered as practical management tools that could be employed by those using fish if they wish to minimize stress and improve health. The opportunity to have a sense of control over stress or being able to anticipate and prepare for stress improves the ability of fish to cope with any stressors in their environment. Inescapable, unpredictable, or chronic stress leads to loss of control and allostatic overload. This can result in behavioral abnormalities leading to displaced aggression and stereotypical behavior. Thus, allowing fish to have other behavior options such as hiding or redirecting behavior can be provided by environmental enrichment. Conditioning fish to associate cues with the onset of a stress allows them to anticipate and prepare for stress, which can be beneficial. Operant conditioning, where fish can operate self-feeders, allows fish to control their own foraging behavior and also has positive effects on fish welfare. Providing the right kind of environmental and cognitive stimulation along with optimal environmental conditions, appropriate feeding regimes and social contact appear to be key to reducing stress in captive contexts if this is logistically possible. Practices in a variety of fish industries are considered where stress may be elevated with countermeasures suggested. Future studies should investigate implementing these factors to understand their impact in different circumstances and in different species if reducing stress is important. The development of robust stress indicators and automated alert systems based on behavior or environmental parameters to detect fish health will be vital for the assessment and alleviation of stress.