Behavioural indicators of welfare in farmed fish

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.Fundação para a Ciência e Tecnologia, Portugal [SFRH/BPD/42015/2007]info:eu-repo/semantics/publishedVersio

Domestication et comportement chez les poissons téléostéens

National audienceOne of the major objective of domestication is the selection of lines with low aggressiveness and a high growth potential. Analyses of domesticated animals traits often illustrate numerous changes in behaviour due to rearing environment. However there are few reports of these changes in fish. In the present paper, we first describe how behaviour is affected by rearing and then discuss how sensory organs and behavioural abilities are modified during development under breeding conditions. Rearing conditions modify feeding behaviour particularly because food distribution do not necessary follow biological rhythm and food is often available in larger amount compared to wild-type situations. In particular food distribution mode may favour aggressiveness. Rearing conditions (stream, fish density...) are also susceptible to modify spatial distribution of fish and relationship between fish in their closed environment. In particular, fish often reduce their inter-individual distances which may also have detrimental influences on their aggressiveness. Several behavioural abilities seem to be affected by development in breeding conditions and this appears to be related to modification of sensory organs. This includes modification of the lateral line system, eye and smell. These modifications are often associated to a lowering of watchfulness threshold which in turn modifies behaviour and particularly escape responses from potential predators. A modification of chromatic adaptation has also been shown for flat fishes. In conclusion, the analysis of behavioural modifications is of utmost importance to identify indicators of domestication progress which must be taken into account to guarantee cultured fish welfare and thus rearing sustainability.Un des principaux objectifs de la domestication est de sélectionner des lignées à haut potentiel de croissance et à faible agressivité. L’étude des caractéristiques des animaux domestiqués montre souvent de nombreux changements comportementaux dus aux conditions d’élevage, mais très peu de données sont disponibles chez les poissons. Cet article décrit d’abord comment la mise en élevage affecte certains comportements, notamment alimentaires et natatoires, puis présente les modifications, au cours du développement, des organes sensoriels et des aptitudes comportementales. Concernant le comportement alimentaire, les modifications sont principalement dues au fait que la distribution d’aliment ne correspond pas nécessairement au rythme biologique des poissons et que la quantité d’aliment disponible est souvent bien supérieure en élevage comparé au milieu naturel. Le mode de distribution peut également influencer l’agressivité. Les conditions d’élevage (courant, densité animale …) peuvent avoir des conséquences sur l’agressivité des poissons, en modifiant leur répartition spatiale, avec en particulier une réduction de la distance interindividuelle. Le développement des poissons en milieu d’élevage semble affecter certaines aptitudes comportementales en relation avec des modifications de leurs organes sensoriels (yeux, ligne latérale et odorat). Ces modifications sont généralement associées à une diminution de la vigilance avec notamment des conséquences sur la capacité à échapper aux prédateurs potentiels. Chez les poissons plats, le maintien en élevage modifie également l’adaptation chromatique. En conclusion, l’analyse des modifications comportementales induites par la domestication est un outil nécessaire pour identifier les facteurs à prendre en compte afin d’identifier la mise en place du processus de domestication, de garantir le bien-être des poissons et ainsi la durabilité du système d’élevage

Activity patterns, home-range size, and habitat utilization of Sarpa salpa (Teleostei : Sparidae) in the Mediterranean Sea

Acoustic telemetry was used to record diel movement and habitat utilization of the salema (Sarpa salpa) (Teleostei: Sparidae) during three consecutive summers from 2000 to 2002 in the Calvi and Achiarina bays of Corsica in the Mediterranean Sea. A total of 18 fish was equipped with acoustic transmitters inserted in the body cavity, 13 were tracked in the Bay of Calvi (275 mm +/- 26.9 L-F), and 5 in Achiarina Bay (260 mm +/- 33.6 LF). Two different systems were used to track the fish. The one used in the Bay of Calvi was a manual receiver and a directional hydrophone. The second system, used in Achiarina Bay, was a radioacoustic-positioning (RAP) system that continuously monitored the movements of the fish. Fish positions were put in a geographic information system (GIS) with information on the substratum and depth. Two patterns of behaviour could be identified in the three years. Either the fish had clearly defined daytime as opposed to night-time areas of residency, characterized by different depths and substrata or the fish persistently occupied the same sites during both day and night. In the Bay of Calvi, six fish were released I km from the capture site. All of them showed homing ability and returned to the site within 48 h

Advances in invertebrates and fish telemetry

This paper analyses acoustic tagging of 8 yellowfin tunas (#Thunnus albacares$, Bonnaterre, 1788) undertaken around Fish Aggregating Devices (FADs) in La Reunion island (Indian Ocean). Emphasis is laid on the horizontal movements and thus complete previous studies on vertical movements around the same FADs. The first result of the present study deals with the relative dwelling time of yellowfin over the distance to FAD where tagged, in 0.9 km intervals. Distributions of dwelling time are different between day and night. During daytime, the fishes remain in the close vicinity of the FAD (mostly within a 1.8 km radius), whilst a drastic disassociation to the FAD occurs at night. During the day, the attractive influence of the FAD disappears 9.3 km away ; this finding leads to the suggestion that a minimum distance of 18 km between neighbouring FADs should be applied in La Reunion to avoid overlapping radii of influence. The second group of results points out the potential use of the vertical and total swimming speeds as indicators of the foraging activity of the fish and of the type of movements (behaviour of tight association to FAD, transit among FADs or offshore migration, away from the area of FADs). The day/night change affects the vertical activity, with large magnitude of vertical movements exhibited at night. The total speed during the offshore movements is estimated about 1.2 m/s : the shift from a phase of tight association to FAD toward a phase of transit movement is characterised by an increase of the total speed. A typology of the relationships between swimming speed and feeding activity is proposed and discussed. (Résumé d'auteur

An assessment of the upstream migration and reproductive behaviour of allis shad (Alosa alosa L.) using acoustic tracking

 We provide a detailed description of the migratory and reproductive behaviour of allis shad (Alosa alosa L.), a species that is in decline in Europe. Adult swimming behaviour during the last part of upstream migration and on a spawning ground downstream of an insurmountable dam was studied in detail and its main features identified, “characterized” in this context. Mobile telemetry and a fixed telemetry system were used to record fish positions and to monitor 23 acoustically tagged individuals (17 females and six males) during the 2001 and 2002 reproductive seasons. Allis shad showed considerable exploratory behaviour, and a rest area was observed 1.5 km downstream of the spawning ground. Thirteen individuals were observed on the spawning area, though both males and females spent most of their time (70–99%) away from it. Male and female residency times on the spawning area were, respectively, 1–11 days and 1–7 days, and females were observed during both day and night on the spawning ground. In 2002, an analysis of the 3D swimming behaviour on the spawning ground of six individuals allowed us to estimate the number of spawning events per fish. Males participated in more spawning acts (up to 60) than females (0–2

Daily activity rhythms of the African catfish Heterobranchus longifilis (Clariidae) in an experimental enclosure

The swimming, air-gaping, and agonistic behaviours of Heterobranchus longifilis (318 +/- 67 mm) were examined while fish were in a fasted state under 12L: 12D and variable group size ( 2, 5, 10 and 15 fish) in a 1000-L aquarium. Fish exhibited a predominantly nocturnal activity pattern independent of group size. A diurnal peak of activity occurred, however, at the usual feeding time. A reduction in frequency of agonistic interactions was observed in larger groups. Five fish were then observed under 72L: 0D and 0L: 72D. The nocturnal activity pattern remained, contrary to the diurnal peak, and was independent of the duration of illumination or darkness. These results suggest the absence of biological clock in H. longifilis, although fish may somehow be influenced by past feeding experience. Behavioural plasticity in this species may provide potential for aquaculture in northern latitudes