Fish welfare and genomics

Abstract

There is a considerable public and scientific debate concerning welfare of fish in aquaculture. In this review, we will consider fish welfare as an integration of physiological, behavioral, and cognitive/emotional responses, all of which are essentially adaptative responses to stressful situations. An overview of fish welfare in this context suggests that understanding will rely on knowledge of all components of allostatic responses to stress and environmental perturbations. The development of genomic technologies provides new approaches to this task, exemplified by how genome-wide analysis of genetic structures and corresponding expression patterns can lead to the discovery of new aspects of adaptative responses. We will illustrate how the genomic approach may give rise to new biomarkers for fish welfare and also increase our understanding of the interaction between physiological, behavioral, and emotional responses. In a first part, we present data on expression of candidate genes selected a priori. This is a common avenue to develop molecular biomarkers capable of diagnosing a stress condition at its earliest onset, in order to allow quick corrective intervention in an aquaculture setting. However, most of these studies address isolated physiological functions and stress responses that may not be truly indicative of animal welfare, and there is only rudimentary understanding of genes related to possible cognitive and emotional responses in fish. We also present an overview on transcriptomic analysis related to the effect of aquaculture stressors, environmental changes (temperature, salinity, hypoxia), or concerning specific behavioral patterns. These studies illustrate the potential of genomic approaches to characterize the complexity of the molecular mechanisms which underlies not only physiological but also behavioral responses in relation to fish welfare. Thirdly, we address proteomic studies on biological responses to stressors such as salinity change and hypoxia. We will also consider proteomic studies developed in mammals in relation to anxiety and depressive status which may lead to new potential candidates in fish. Finally, in the conclusion, we will suggest new developments to facilitate an integrated view of fish welfare. This includes use of laser microdissection in the transcriptomic/proteomic studies, development of meta-analysis methods for extracting information from genomic data sets, and implementation of technological advances for high-throughput proteomic studies. Development of these new approaches should be as productive for our understanding of the biological processes underlying fish welfare as it has been for the progress of pathophysiological research.

Change in redox state and heat shock protein expression in an Indian major carp <i>Cirrhinus cirrhosus</i> exposed to zinc and lead

“…Aquatic organisms are often exposed to an acute change in the heavy metal composition of the environment (Nakano, 2007;Prunet et al, 2012). Exposure of fish to such an environment might result in a sequence of biochemical as well as physiological alteration at tissue and cellular levels.…”

“…In addition to neuro-endocrine stress response in the organismal levels, there occurs a cellular stress response following exposure to different heavy metals. These stress responses in organisms might affect their general health status, disease resistance, growth and reproductive activity (Pickering et al, 1993;Prunet et al, 2012).…”

Effect of excessive doses of oxytetracycline on stress-related biomarker expression in coho salmon

“…Exposure of organisms to stressors may result in a series of biochemical and physiological changes (Iwama et al 2006;Nakano 2007;Nakano 2011;Nakano et al 2013;Nakano et al 2014;Nakano et al 2015;Nakano and Takeuchi 1997;Pickering 1993;Prunet et al 2012;Regoli and Giuliani 2014). At the organismal level, these changes are mediated by the neuroendocrine system.…”

“…In addition to this neuroendocrine stress response, there is a cellular stress response following exposure to stressful situations. These stress responses in organisms affect their general health, disease resistance, growth, and reproduction (Barton and Iwama 1991;Nakano 2011;Pickering 1993;Prunet et al 2012). Therefore, it is important to elucidate the features and mechanisms by which environmental stress influences fitness at both molecular and organismal levels, in order to improve the health of cultured fish.…”

“…The growth of fish is known to be genetically regulated and to also be influenced by cellular, endocrinological, and environmental factors. The response of endocrine tissue is affected by the integration of external stimuli with internal signals according to the physiological state (Barton and Iwama 1991;Iwama et al 2006;Kameda et al 2008;Moriyama et al 2000;Nakano 2011;Pickering 1993;Prunet et al 2012;Reineck 2010). Fish growth can be enhanced by several factors such as changes in the endocrine system of the animal (Donaldson et al 1979;Pickering 1993).…”