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AEI
Aquaculture Environment Interactions

    AEI prepress abstract   -  DOI: https://doi.org/10.3354/aei00367

    Vaccine-induced reduced growth in Atlantic salmon Salmo salar smolts is not affected by conditions expected to alter metabolic rate for seven weeks post vaccination

    Thomas W. K. Fraser*, Per Gunnar Fjelldal, Ingunn Sommerset, Tina Søfteland, Ole Høstmark, Mark D. Powell, Vegar Heen, Tom J. Hansen

    *Corresponding author:

    ABSTRACT: Oil-adjuvanted vaccines reduce long-term growth in farmed Atlantic salmon, possibly via an increase in metabolic rate due to the energetic demands of the immune system. We tested this hypothesis by comparing sham vaccinated to vaccinated smolts (total n = 2096, approx. 80 g) under different scenarios of water temperature (12 vs. 17°C, n = 1048/temperature) and oxygen (O2) saturation (60, 70, 80, and 100%, n = 524/O2 saturation) in order to manipulate metabolic rate and O2 availability. We expected a more severe vaccination effect under conditions of high water temperature and low O2 saturation. Groups were kept in duplicate tanks under controlled temperature and hypoxia conditions for 7 wk post-vaccination before being transferred to uncontrolled common-garden natural conditions for 5 mo in a sea-cage. Body mass and length was recorded at the initiation and end of the controlled and uncontrolled environmental conditions. Vaccination and low O2 saturation at 17°C significantly reduced body mass (vaccination by 13 and 3% and 60% O2 saturation by 9 and 20% at the end of the tank and sea-cage periods, respectively). However, there was no interaction between vaccination, temperature, and O2 saturation at the end of the tank or sea-cage period, lending no support to our hypothesis. A secondary observation was that emaciated ‘loser fish’ were mainly associated with the 17 °C and low (mainly 60%) O2 saturation treatment. In conclusion, although vaccination led to a reduction in body mass, this effect was not influenced by environmental conditions expected to alter metabolic rate.