Use of a feed additive to improve water quality, gut health, microbiota and fish performance in Atlantic salmon in recirculating aquaculture systems at higher temperature.
The goal of this trial is to study the effects of a feed additive on water quality management, gut health, gut microbiota and fish growth performance in high temperatures and gut health-challenged Atlantic salmon. Parts of the trial will be conducted with temperatures outside of the optimal temperature range of Atlantic salmon. This, coupled with necessary handling of the fish for weighing and sampling at the midpoint of the experiment, may cause moderate stress to the fish.
The use of recirculating aquaculture systems (RAS) allows for greater control over the quality of the water in which fish are cultured, including control over water temperature. However, in some areas where Atlantic salmon are raised in these systems, unseasonably warm weather can make it difficult to efficiently chill the water to the optimal temperature, which may result in reduced growth and potential health issues. One mechanism for this reduced growth may be interruption of the gut microbiota, or exacerbation of digestive system pathologies. In addition, reduction or removal of nitrogenous waste is a primary concern for the efficient management of these high density systems. Identification of compounds which can ameliorate the impact of these problems, and assessment of the incorporation of these into commercial fish feeds is an important step in ensuring the welfare of fish in RAS.
The proposed trial will require 840 Atlantic salmon, with a start weight of 300 grams. The number of fish is the minimum to maintain an appropriate density for observation of effects of the treatment on water quality parameters, and approaching a commercially relevant density, while allowing sampling at the mid-point of the experiment. The fish will be raised at a temperature within the optimal range of Atlantic salmon for six weeks before mid-point sampling, followed by a gradual increase of water temperature to a suboptimal level over a period of 3 weeks, before a final period of 4 weeks at this temperature.
It is anticipated that the fish may experience a slight reduction in appetite due to the suboptimal temperature, and mild to moderate gut irritation.
The use of recirculating aquaculture systems (RAS) allows for greater control over the quality of the water in which fish are cultured, including control over water temperature. However, in some areas where Atlantic salmon are raised in these systems, unseasonably warm weather can make it difficult to efficiently chill the water to the optimal temperature, which may result in reduced growth and potential health issues. One mechanism for this reduced growth may be interruption of the gut microbiota, or exacerbation of digestive system pathologies. In addition, reduction or removal of nitrogenous waste is a primary concern for the efficient management of these high density systems. Identification of compounds which can ameliorate the impact of these problems, and assessment of the incorporation of these into commercial fish feeds is an important step in ensuring the welfare of fish in RAS.
The proposed trial will require 840 Atlantic salmon, with a start weight of 300 grams. The number of fish is the minimum to maintain an appropriate density for observation of effects of the treatment on water quality parameters, and approaching a commercially relevant density, while allowing sampling at the mid-point of the experiment. The fish will be raised at a temperature within the optimal range of Atlantic salmon for six weeks before mid-point sampling, followed by a gradual increase of water temperature to a suboptimal level over a period of 3 weeks, before a final period of 4 weeks at this temperature.
It is anticipated that the fish may experience a slight reduction in appetite due to the suboptimal temperature, and mild to moderate gut irritation.