Proactive avoidance behaviour and pace-of-life syndrome in Atlantic salmon

Citation

Damsgård B, Evensen TH, Øverli Ø, Gorissen M, Ebbesson LOE, Rey S & Höglund E (2019) Proactive avoidance behaviour and pace-of-life syndrome in Atlantic salmon. Royal Society Open Science, 6 (3), Art. No.: 181859. https://doi.org/10.1098/rsos.181859

Abstract
Individuals in a fish population differ in key life history traits such as growth rate and body size. This raises the question if such traits cluster along a fast-slow growth continuum according to a pace-of-life syndrome (POLS). Fish species like salmonids may develop a bimodal size distribution, providing an opportunity to study the relationships between individual growth and behavioural responsiveness. Here we test whether proactive characteristics (bold behaviour coupled with low post-stress cortisol production) are related to fast growth and developmental rate in Atlantic salmon (Salmo salar). Boldness was tested in a highly controlled two-tank hypoxia test were oxygen levels were gradually decreased in one of the tanks. All fish became inactive close to the bottom at 70% oxygen saturation. At oxygen saturation level of 40% a fraction of the fish actively sought out to avoid hypoxia. A proactive stress coping style was verified by lower cortisol response to a standardized stressor. Two distinct clusters of bimodal growth trajectories were identified, with fast growth and early smoltification in 80% of the total population. There was a higher frequency of proactive individuals in this fast-developing fraction of fish. The smolts were associated with higher post-stress plasma cortisol than parr, and the proactive smolts leaving hypoxia had significant lower post-stress cortisol than the stayers. The study demonstrated a link between a proactive coping and fast growth and developmental ratio, and suggests that selection for domestic production traits promotes this trait cluster.

Keywords
coping styles; personality; life history; hypoxia; stress; cortisol

Journal
Royal Society Open Science: Volume 6, Issue 3

• Published version