Diploid and Triploid comparison of perfomance and coping capacity under unpredictable chronic stress
1 Purpose:Avoiding genetic interactions between wild and farmed Atlantic salmon is regarded as one of the major requirements for a sustainable salmon aquaculture industry. For this reason, farming functional sterile triploids has been suggested as a possible solution. However, in recent studies (Madaro et al.2021) triploid salmon in commercial settings exhibited reduced survival, lower performance and welfare, and scored, on average, a lower quality rating during primary processing. Possibly, while triploid and diploid salmon perform similarly under optimal conditions (Maxime 2008; Oppedal et al. 2003), triploids performance may be reduced/impaired under suboptimal rearing conditions when compared to diploids (reviewed in Maxime 2008).While acute stress tests have been performed on triploid fish (es, Benfey and Biron 1994, 2000) almost none is known about triploid performance and coping capability under suboptimal or chronic stress condition.
2 Distress:On this purpose, we want to design a 21days long unpredictable chronic stress (UCS) trial similar the one published by Madaro et al 2015 or Løvmoet al. 2020 employing a mix of mild stressor given in a random manner 2/3 times a day. At the end of the 21 day of UCS, al groups will be exposed to a stress test by a novel stressor, that is netting fish out from their holding tanks into a single one furnished with wheels and transported next door. Here they will be transferred in groups of 10 into new tanks before being sampled after 15, 30, 45, 60, 90, 120, 240 and 300 min post-stress. 10 fish will will be sampled before the stress test (0 min).
3 Expected benefit: A direct comparison of diploid and triploid under UCS regime will put in evidence differences in the coping capacity and performance of salmon with different ploidy and will also add new insight in the dynamic physiological changes that occur at every level of the hypothalamic-pituitary gland-interrenal gland (HPI) axis as a result of chronic stress in Atlantic salmon.
4 Number of animals, and what kind:We will employ the lowest possible number of animals:
4 Groups in triplicate (Triploid UCS; Triploid Control; Diploid UCS; Diploid Control) with n.60 parr (about 80-100g) per tank for a total of 720 fish (360 diploid and 360 triploid). Genetic differences will be reduced using clonal-lines (aquagen strain)
5 How to adhere to 3R: The 3Rs: Replacement: not possible. Reduction: restricting samples to the last day of the UCS trial. Ten killed fish per sample point is regarded a minimum as a proportion of the samples; samples often have to be rejected, for instance due to outliers or hemolysis in plasma, leaving a lower number for statistical analysis. The biomasses are the minimum required to mesure O2 uptake in the tanks. Refinement: The fish will be held in their home tank until stressed, and thereafter transferred into similar tanks at the same temperature and left undisturbed until sampled. Stressors are chosen to secure a clear stress response but still avoid sever stress that could lead physiological outcome different from stress itself.
2 Distress:On this purpose, we want to design a 21days long unpredictable chronic stress (UCS) trial similar the one published by Madaro et al 2015 or Løvmoet al. 2020 employing a mix of mild stressor given in a random manner 2/3 times a day. At the end of the 21 day of UCS, al groups will be exposed to a stress test by a novel stressor, that is netting fish out from their holding tanks into a single one furnished with wheels and transported next door. Here they will be transferred in groups of 10 into new tanks before being sampled after 15, 30, 45, 60, 90, 120, 240 and 300 min post-stress. 10 fish will will be sampled before the stress test (0 min).
3 Expected benefit: A direct comparison of diploid and triploid under UCS regime will put in evidence differences in the coping capacity and performance of salmon with different ploidy and will also add new insight in the dynamic physiological changes that occur at every level of the hypothalamic-pituitary gland-interrenal gland (HPI) axis as a result of chronic stress in Atlantic salmon.
4 Number of animals, and what kind:We will employ the lowest possible number of animals:
4 Groups in triplicate (Triploid UCS; Triploid Control; Diploid UCS; Diploid Control) with n.60 parr (about 80-100g) per tank for a total of 720 fish (360 diploid and 360 triploid). Genetic differences will be reduced using clonal-lines (aquagen strain)
5 How to adhere to 3R: The 3Rs: Replacement: not possible. Reduction: restricting samples to the last day of the UCS trial. Ten killed fish per sample point is regarded a minimum as a proportion of the samples; samples often have to be rejected, for instance due to outliers or hemolysis in plasma, leaving a lower number for statistical analysis. The biomasses are the minimum required to mesure O2 uptake in the tanks. Refinement: The fish will be held in their home tank until stressed, and thereafter transferred into similar tanks at the same temperature and left undisturbed until sampled. Stressors are chosen to secure a clear stress response but still avoid sever stress that could lead physiological outcome different from stress itself.