Behavioural indicators of welfare in farmed fish

Abstract

Behaviour represents a reaction to the environment as fish perceive it and is therefore a key element of fish welfare. This review summarises the main findings on how behavioural changes have been used to assess welfare in farmed fish, using both functional and feeling-based approaches. Changes in foraging behaviour, ventilatory activity, aggression, individual and group swimming behaviour, stereotypic and abnormal behaviour have been linked with acute and chronic stressors in aquaculture and can therefore be regarded as likely indicators of poor welfare. On the contrary, measurements of exploratory behaviour, feed anticipatory activity and reward-related operant behaviour are beginning to be considered as indicators of positive emotions and welfare in fish. Despite the lack of scientific agreement about the existence of sentience in fish, the possibility that they are capable of both positive and negative emotions may contribute to the development of new strategies (e.g. environmental enrichment) to promote good welfare. Numerous studies that use behavioural indicators of welfare show that behavioural changes can be interpreted as either good or poor welfare depending on the fish species. It is therefore essential to understand the species-specific biology before drawing any conclusions in relation to welfare. In addition, different individuals within the same species may exhibit divergent coping strategies towards stressors, and what is tolerated by some individuals may be detrimental to others. Therefore, the assessment of welfare in a few individuals may not represent the average welfare of a group and vice versa. This underlines the need to develop on-farm, operational behavioural welfare indicators that can be easily used to assess not only the individual welfare but also the welfare of the whole group (e.g. spatial distribution). With the ongoing development of video technology and image processing, the on-farm surveillance of behaviour may in the near future represent a low-cost, noninvasive tool to assess the welfare of farmed fish.

Modelling swimming activities and energetic costs in European sea bass (Dicentrarchus labraxL., 1758) during critical swimming tests

“…ATP stores may be replenished after intense exercise within a 1-h post-exercise recovery period (Carbonara et al 2010), but re-synthesis of glycogen and recovery from lactate accumulation can take twelve hours or more (Marras et al 2013). The proportion of red and white muscle usage reflects physiological state (Lembo et al 2007) and capability to cope with environmental stress Marine and Freshwater Behaviour and Physiology 13 (Martins et al 2012). Whether such changes can be used as an indicator of poor or good welfare is, however, species and context dependent (Herbert & Steffensen 2005).…”

Cortisol and finfish welfare

“…Sánchez et al (2009) observed anticipatory activity of feeding, which could be interpreted as a response to a positive stimulus (see also review by Martins et al 2011), but this was associated with lower plasma cortisol levels than in fish that did not show this behaviour. The multitude of studies describing cortisol elevation in fish relates to stimuli interpreted as negative stressors.…”

“…The underlying assumption is that negative feelings in animals will manifest in a stress response, analogous to that which we recognise in humans (Korte 2001;Levine et al 2007). [Please note that behavioural indicators provide an additional potential means of assessing fish feelings (reviewed by Martins et al 2011). Nevertheless, this route may be compromised due to the suggestion that fish, as a common prey item, may not exhibit behavioural changes that could increase vulnerability to predators (CCAC 2005)].…”

EVALUATION OF MORINGA OLEIFERA LEAVES AND THEIR AQUEOUS EXTRACT IN IMPROVING GROWTH, IMMUNITY AND MITIGATING EFFECT OF STRESS ON COMMON CARP (Cyprinus Carpio) FINGERLINGS

“…In addition, gills are important targets for cortisol in fish (Wendelaar Bonga, 1997). Therefore, opercular movement reflects stress level posed on fish (Martins et al, 2011).…”