Chronic social stress in rainbow trout: Does it promote physiological habituation?

Abstract

The effect of chronic social stress on growth, energetic substrates and hormones was tested in rainbow trout, Oncorhynchus mykiss. After a 14-day isolation period, the fish were paired for 8 days. In order to expose fish to chronic intermittent social contact during pairing, they were maintained in direct contact with each other during the first day. After that, a black plastic screen partition was introduced in each tank, preventing direct contact between animals. Every day the partition was removed for 30 minutes, allowing physical interaction between fish. At the end of pairing period, they were isolated again for 13 days. Fish were weighed and blood was sampled frequently during the experiment. Plasma levels of cortisol, growth hormone, glucose, total protein and free amino acids were quantified. Both dominants and subordinates had specific growth rate decreased during the pairing period and but only subordinates increased when the stressor was abolished (dominants: 0.32 ± 0.21 and 0.24 ± 0.41, subordinates: -0.77 ± 0.29 and 0.37 ± 0.31, respectively). Dominants showed a higher cortisol level one week after pairing condition had been abolished than subordinates (dominants: 56.76 ± 13.26, subordinates:31.89 ± 13.36). We conclude that chronic condition of intermittent social stress represents a stressful condition for animals of both hierarchical ranks and a treatment of one daily short direct contact between conspecifics does not promote habituation in fish, as mentioned for other stressors.social stress, energetic of stress, hierarchical dominance, rainbow trout, Oncorhynchus mykiss.

A multivariate comparison of the stress response in three salmonid and three cyprinid species: evidence for inter‐family differences

“…Of the six species whose stress response was measured in the present study, O. mykiss has been best described previously. The baseline and stress-induced levels of plasma cortisol, glucose, lactate and total amino acids observed in O. mykiss during the present study are similar to those reported for fish exposed to broadly similar stressors (Pottinger & Carrick, 1999b, 2000Wagner et al, 2002;Trenzado et al, 2003;Momoda et al, 2007;Weber & Silverstein, 2007;Cairns et al, 2008;Fernandes-de-Castilho et al, 2008;Gesto et al, 2008). For S. trutta, fewer data are available for comparison, but the data presented here are again largely consistent with earlier results (Pickering et al, 1982(Pickering et al, , 1986Norris et al, 1999;Ruane et al, 1999).…”

Seabream (Sparus aurata) long-term dominant-subordinate interplay affects phagocytosis by peritoneal cavity cells

“…The subordinate fish group values were significantly discriminated in the canonical roots as compared with the control and a fish; these values were influenced differently in the roots at a different time. Fernandes-de-Castilho et al (2008) showed that contact between conspecific fish constituted a chronic form of social stress; the increased plasma cortisol in socially subordinate Oncorhynchus mykiss and Salmo trutta has also been reported (Sloman et al, 2001).…”

“…In fish, social defeat refers to losing a confrontation among conspecific animals, is a powerful stressor that can lead to drastic changes in animal physiology and behaviour (Sloman and Armstrong, 2002;Martins et al, 2006;Fernandes-de-Castilho et al, 2008;Edeline et al, 2010). For socially dominant individuals, the ''winner effect'' underlies a higher probability of winning subsequent aggressive encounters (Rutte et al, 2006).…”

“…Behavioural effects include appetite inhibition (Kramer et al, 1999;Meerlo et al, 1997;Øverli et al, 1998), reduced aggression (Blanchard et al, 1995;Höglund et al, 2001), decreased reproductive behaviour (D 'Amato, 1988;Perret, 1992), and enhanced submissive and defensive behaviours toward conspecifics (Blanchard et al, 1993;Siegfried et al, 1984). Moreover, contact between conspecific fish does not promote habituation (Fernandes-de-Castilho et al, 2008). Changes in aggression levels and stress physiology are used as welfare indicators, and the elevation of these parameters has been associated with impaired welfare (FSBI, 2002).…”

<b>Psychological Stress and Welfare in Fish</b>

“…Many studies have been evaluating the effect of social status and social stressors on the HPI axis and other related systems (e.g. Munro & Pitcher, 1985;Fox et al, 1997;Pottinger & Carrick, 2001;Clement et al, 2005;Gilmour et al, 2005;Earley et al, 2006;Fernandes-De-Castilho et al, 2008). Social stressors may primarily elicit fear, danger recognition and anticipation of threatening events with concomitant neuroendocrine responses (Chandroo et al, 2004a).…”