The behaviour of Atlantic salmon in relation to efficient cage-rearing

Juell, Jon‐Erik

doi:10.1007/bf00043005

Cited by 78 publications

(67 citation statements)

References 57 publications

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“…Some fish species in nature school together while other fish species are more territorial, and in some cases escapes from sea cages might be a part of a mechanism to disperse from other individuals in the population. For example, groups of Atlantic salmon normally swim in a circular pattern along the perimeter of the cage wall (Fernö et al 1995, Juell 1995, while Atlantic cod is described as an exploratory feeder (van Duren & Glass 1992, Hart 1993, Løkke-borg 1998, which uses a wide range of feeding strategies and thus a less regular movement pattern than salmon, increasing the chance of finding a hole in the net. For example, cod in sea cages spend much of the time close to the net wall, not coordinated with conspecifics and with a continuously changing speed and direction (Rillahan et al 2011), corresponding with the movement pattern observed in the present study.…”

Section: Discussionmentioning

confidence: 99%

Net-biting and escape behaviour in farmed Atlantic cod Gadus morhua: effects of feed stimulants and net traits

Damsgård¹,

Høy²,

Uglem³

et al. 2012

Aquacult. Environ. Interact.

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Preventing farmed fish from escaping sea cages is a major challenge for developing sustainable aquaculture practices. In this study, the individual behaviour of Atlantic cod Gadus morhua to inspect and bite the net was investigated in 4 replicate multi-patch experiments, using underwater video techniques and behavioural event recording. The experimental system included a tank enclosure where cod were presented with 6 separate net panels: duplicate pairs of plain control nets and 2 different treatment panels. Four holes were made in the treatment panels, 3 of which were mended with different repair techniques including short and loose thread ends and contrasting colour repair threads. Behavioural effects of feed stimulants were studied before, during and after a feed source was placed outside the net. The cod inspected and bit the net systematically, significantly focusing on loose threads or minor damage on the net, and the fish were capable of causing severe net damage within a few days. The observed behaviours were related to hunger level and feed stimulation, and increased significantly during times when a feed source was present outside the net wall. Few bites were observed, and almost no measureable damage was recorded to plain control panels and the area around unrepaired holes during the treatment. Repairs made with white and black threads, and loose, long ends were significantly more damaged than repairs made with short thread ends and threads of similar colour as the net. The experiments demonstrated how a behavioural approach might be used in interpretation of a practical problem in aquaculture, and the results will be useful in the development of technology and escape mitigation strategies.

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Section: Discussionmentioning

confidence: 99%

Net-biting and escape behaviour in farmed Atlantic cod Gadus morhua: effects of feed stimulants and net traits

Damsgård¹,

Høy²,

Uglem³

et al. 2012

Aquacult. Environ. Interact.

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“…In fish tanks and cages, there will usually be areas that are more favourable than the others and restricting these volumes will result in a trade-off between packing density (number of fish per cubic metre, Juell and Fosseidengen 2004) and environmental conditions. Especially in sea cages, there can be large environmental gradients, with highly variable temperature, salinity, oxygen, current speed and light conditions (Juell 1995, Juell and Fosseidengen 2004, Johansson et al 2006. Fish are attracted to the most optimal areas and avoid the unfavourable ones as a result of both attractions to a part of the rearing volume with preferred environmental conditions and avoidance/repulsion from areas with poor environmental conditions.…”

Section: Group Swimming Behaviourmentioning

confidence: 99%

“…Fish are attracted to the most optimal areas and avoid the unfavourable ones as a result of both attractions to a part of the rearing volume with preferred environmental conditions and avoidance/repulsion from areas with poor environmental conditions. Such conditions cause a trade-off between packing density and the benefits of being in the relatively best areas, and at high stocking densities, the less competitive fish will be forced to stay in suboptimal areas (Juell 1995, Johansson et al 2006). The behaviour of the fish can also have an effect on environmental conditions, and the high local concentrations of fish can cause reduced water flow and increased oxygen consumption leading to areas with hypoxia.…”

Section: Group Swimming Behaviourmentioning

confidence: 99%

Behavioural indicators of welfare in farmed fish

Martins¹,

Galhardo²,

Noble³

et al. 2011

Current Views on Fish Welfare

120

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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 rewardrelated operant behaviour are beginning to be considered as indicators of positive emotions and welfare in

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“…In terms of production efficiency, it is well documented that moderate exercise provide Swimming in a circular structure might reduce stress and improve growth efficiency due 291 to less confrontations within the sea cage (Juell, 1995), while increased appetite has been 292 observed to coincide with a change from unstructured to circular schooling (Fernö et al,293 1988). Concerning acceptable fish welfare and optimal growth rates, it may be argued that considered in welfare assessments at exposed locations, since they may impair swimming 324 capabilities (Brett, 1964;Jones, 1971).…”

mentioning

confidence: 99%