Divergent stress coping styles in juvenile brown trout (Salmo trutta).

Two distinct stress coping styles, proactive and reactive, have been stated in various animal studies. This divergence in coping has also been indicated in salmonid fish. Here, we test the hypothesis that divergent stress coping styles are identifiable in a sea-ranched brown trout population. To that end, we used a series of tests on individual juvenile brown trout, with each test including a common key aspect of the two different coping styles. Using a clustering method (SAS: PROC FASTCLUS), two groups that clearly differed both in blood chemistry (noradrenalin and adrenalin levels) following confinement and in behavior during hypoxia were identified.