Aquaculture Europe 2023

September 18 - 21, 2023


Add To Calendar 19/09/2023 15:30:0019/09/2023 15:45:00Europe/ViennaAquaculture Europe 2023A COMPARATIVE STUDY OF THE PHYSIOLOGICAL RESPONSES OF ACUTE AND CHRONICALLY STRESSED DIPLOID AND TRIPLOID ATLANTIC SALMON Salmo salarStrauss 3The European Aquaculture Societywebmaster@aquaeas.orgfalseDD/MM/YYYYaaVZHLXMfzTRLzDrHmAi181982


A. Madaro*a , F. Lai b,  P.G. Fjelldal a , T. Hansen a, V. Gelebart b, I. Røn nestad b , R.E. Olsen ac and L.H.  Stien a

a Institute of Marine Research, NO-5984 Matredal, Norway

 b Department of Biological Sciences, University of Bergen, P.O. Box 7800, 5020 Bergen, Norway

c Norwegian University of Science and Technology (NTNU), Department of Biology, 7491 Trondheim, Norway

E-mail :



 One of the  main concerns for the environment due to salmon  commercial  aquaculture are salmon escapees (Keyser et al., 2018; Besnier et al., 2022). Escapees, breeding with wild conspecifics (Diserud et al., 2022) , have the potential to endanger local wild populations by introducing genetic changes that may  be  maladaptive in nature (Besnier et al., 2022) . Induced triploidization has been adopted  as a strategy  to provoke sterility in commercialy farmed Atlantic salmon. However, triploid salmon  have shown reduced performance and welfare  in commercial settings (Madaro et al., 2021, Stien et al., 2023) . This  has been suggested to  be due to farming  suboptimal  conditions and  impaired  stress coping capacity.  The aim of this study was to compare  physiological responses of  diploid and triploid  salmon  siblings subjected to unpredictable chronic stress .

Materials and methods

Atlantic salmon were reared at the Institute of Marine Research (IMR, Matre, Norway). D iploid and triploid Atlantic salmon  were subjected to a 21- days unpredictable chronic stress (UCS) regime and compared  with fish that were not stressed. The UCS regime involved exposure of fish to seven unpredictable stressors two times a day .  At the end of this period all groups were  tested with an acute stressor (netting and transfer in a new tank) . B lood chemistry and  selected  pituitary genes expression  were used to assess the stress response. Plasma parameters were sampled before (0) and 15 , 30 , 45, 60, 90, 120, 240, 300 min post-stress and included measurements of  plasma ACTH, cortisol, ions, and metabolites. Gene expression analyses were performed at 0, 30, 60, 120, 240 min post-stress.


 Circulating level of ACTH (Fig 1a) and cortisol (Figure 1b) were significantly affected by fish ploidy (diploid vs triploid), type of treatment  and  time. After the stress test, plasma ACTH levels were mostly higher for triploid than  for diploid in both UCS and naïve fish. While pre-stress levels of cortisol were similar between ploidy in both treatments,  plasma  cortisol levels increased predominantly in both UCS and control triploid groups.  More  results will be presented at the EAS conference in Vienna (Austria, 2023).


T he two salmon ploidy groups showed  noteworthy differences  in the  stress response. Post-stress ACTH and c ortisol release in plasma were generally higher in  both triploid groups. Also, triploid fish showed wider post-stress fluctuations in most of the other plasma parameters.  In addition, there were  noteworthy  ploidy  differences in the  expression of genes regulating  the  stress  response  at the  pituitary levels.  The study will  be discussed in more detail at the EAS conference of Vienna ( Austria, 2023).


 This study was part of the  NRS TripWell-projected funded by Norway Royal Salmon.


-Besnier , F. et al.  (2022) ‘Introgression of domesticated salmon changes life history and phenology of a wild salmon population’, Evolutionary Applications, 15(5), pp. 853–864.

 -Diserud , O.H. et al.  (2022) ‘Natural and anthropogenic drivers of escaped farmed salmon occurrence and introgression into wild Norwegian Atlantic salmon populations’, ICES Journal of Marine Science, 79(4), pp. 1363–1379.

- Keyser, F. et al. (2018) ‘Predicting the impacts of escaped farmed Atlantic salmon on wild salmon populations’, Canadian Journal of Fisheries and Aquatic Sciences , 75(4), pp. 506–512.

- Madaro, A. et al. (2021) ‘A comparison of triploid and diploid Atlantic salmon  ( Salmo salar ) performance and welfare under commercial farming conditions in Norway’, Journal of Applied Aquaculture, pp. 1–15. Available at:

 - Stien, L.H., mfl, Production, fasting and delousing of triploid and diploid salmon in Northern Norway – Report for the 2020-generation. Rapport fra havforskningen 2023-20.