Stress in Atlantic Salmon: Response to Unpredictable Chronic Stress

Combinations of stressors occur regularly throughout an animal’s life, especially in agriculture and aquaculture settings. If an animal fails to acclimate to these stressors, stress becomes chronic, and a condition of allostatic overload arises with negative results for animal welfare. In the current study, we describe effects of exposing Atlantic salmon parr to an unpredictable chronic stressor (UCS) paradigm for 3 weeks. The paradigm involves exposure of fish to seven unpredictable stressors three times a day. At the end of the trial, experimental and control fish were challenged with yet another novel stressor and sampled before and 1 h after that challenge. Plasma cortisol decreased steadily over time in stressed fish, indicative of exhaustion of the endocrine stress axis. This was confirmed by a lower cortisol response to the novel stressor at the end of the stress period in chronically stressed fish compared with the control group. In the preoptic area (POA) and pituitary gland, chronic stress resulted in decreased gene expression of 11βhsd2, gr1 and gr2 in the POA and increased expression of those genes in the pituitary gland. POA crf expression and pituitary expression of pomcs and mr increased, whereas interrenal gene expression was unaffected. Exposure to the novel stressor had no effect on POA and interrenal gene expression. In the pituitary, crfr1, pomcs, 11βhsd2, grs and mr were down-regulated. In summary, our results provide a novel overview of the dynamic changes that occur at every level of the hypothalamic-pituitary gland–interrenal gland (HPI) axis as a result of chronic stress in Atlantic salmon.

Effects of Noise on Acoustic Signal Production in Marine Mammals. in Animal Communication and Noise (ed. Brumm, H.) 2, 251–271 (Springer Berlin Heidelberg, 2013).

Acoustic Harassment Device (AHD) Use in the Aquaculture Industry and Implications for Marine Mammals. Proceedings – Institute of Acoustics 19, 267–276 (1997).

Effect of Ultrasonic Cavitation On Small and Large Organisms for Water Disinfection During Fish Transport. Aquaculture Research 49 (3): 1166–75 (2018).

Changes in Hydrolytic Enzyme Activities of Naïve Atlantic Salmon Salmo Salar Skin Mucus Due to Infection With the Salmon Louse Lepeophtheirus Salmonis and Cortisol Implantation. Diseases of Aquatic Organisms 41, 43–51 (2000).

Large-Scale Underwater Noise Pollution From Acoustic Deterrent Devices (ADDs) On the West Coast of Scotland. in (2017).

Acoustic Deterrence of Harmful Marine Mammal-Fishery Interactions: Proceedings of a Workshop held in Seattle, Washington, 20-22 March 1996. (National Marine Fisheries Services – Offices and Science Centers, US Department of Commerce, 1996)

A Mobile Acoustic Localization System for the Study of Free-Ranging Dolphins During Focal Follows. Marine Mammal Science (2008)

Aquaculture Risk Management and Marine Mammal Interactions In the Pacific Northwest.” Aquaculture 183 (3–4): 307–23.

Displacement of Orcinus orca (L.) by high amplitude sound in British Columbia, Canada. ICES Journal of Marine Science 59, 71–80 (2002).