Investigating possible factors which contribute to liquid accumulation in the swim bladders of Atlantic salmon (Salmo salar)
The main objective of this trial is to examine the contributions of submersion and aeration to accumulation of liquid in the swim bladders of Atlantic salmon (Salmo salar). Secondarily we will examine, (a) when liquid begins to accumulate in swim bladders and how rapidly it progresses, (b) how long it takes for swim bladders to clear liquid, and (c) how the chemical composition of liquid in swim bladders changes through time.
In recent trials of several different louse prevention strategies, including skirt barriers, snorkel cages and submersion, accumulation of liquid in salmon swim bladders has been observed. This phenomenon rarely occurs when salmon are held in standard sea cages. This research aims to increase the feasibility of using prevention tools by understanding one of the key welfare risks associated with submersion and aeration.
We propose a research scale experiment with factorial design which will allow us to determine the relative contributions of (a) aeration and (b) submersion on the accumulation of liquid in salmon swim bladders. The trial will be conducted at the Matre Research Station operated by Havforskningsinstituttet. Fish will be held in twelve 5 x 5 x 6m cages to minimize the risks of confounding factors which could affect fish welfare. To ensure statistical confidence, as determined by power analysis, 130 approximately 1500 g salmon smolts will be stocked in each cage, with 3 replicate cages per treatment (Ntotal = 4 treatments x 3 replicates x 130 salmon/tank = 1560 salmon).
Previous work has shown that submersion of salmon in sea cages for 22 days resulted in no significant differences in welfare or growth, but behavior was altered. In this trial we will sample every 5 days to determine when liquid accumulation begins and how quickly it progresses. In addition, behavior observations will be performed 3x per week to minimize the risk of adverse events. Subsequently, although we do not fully understand the welfare implications of liquid accumulation in swim bladders, the level of distress expected for the fish is mild to moderate. Anesthesia will be used for all handling events. All fish will be maintained using best known husbandry practices. Environmental conditions will be monitored daily throughout the trial.
In recent trials of several different louse prevention strategies, including skirt barriers, snorkel cages and submersion, accumulation of liquid in salmon swim bladders has been observed. This phenomenon rarely occurs when salmon are held in standard sea cages. This research aims to increase the feasibility of using prevention tools by understanding one of the key welfare risks associated with submersion and aeration.
We propose a research scale experiment with factorial design which will allow us to determine the relative contributions of (a) aeration and (b) submersion on the accumulation of liquid in salmon swim bladders. The trial will be conducted at the Matre Research Station operated by Havforskningsinstituttet. Fish will be held in twelve 5 x 5 x 6m cages to minimize the risks of confounding factors which could affect fish welfare. To ensure statistical confidence, as determined by power analysis, 130 approximately 1500 g salmon smolts will be stocked in each cage, with 3 replicate cages per treatment (Ntotal = 4 treatments x 3 replicates x 130 salmon/tank = 1560 salmon).
Previous work has shown that submersion of salmon in sea cages for 22 days resulted in no significant differences in welfare or growth, but behavior was altered. In this trial we will sample every 5 days to determine when liquid accumulation begins and how quickly it progresses. In addition, behavior observations will be performed 3x per week to minimize the risk of adverse events. Subsequently, although we do not fully understand the welfare implications of liquid accumulation in swim bladders, the level of distress expected for the fish is mild to moderate. Anesthesia will be used for all handling events. All fish will be maintained using best known husbandry practices. Environmental conditions will be monitored daily throughout the trial.