Stress coping strategies in rainbow trout (Oncorhynchus mykiss) Miriam Vogt There are studies showing that within several vertebrate species, individuals display different sets of coherent behavioural traits to counteract stress. These sets of behaviour have been called coping strategies. In addition, Rainbow trout (Oncorhynchus mykiss) have been found to differ in their plasma cortisol response to a standardized stressor (confinement). These responses are a stable trait with a moderate to high heritability. The aim of this study was to find out if rainbow trout displays a consistent behavioural strategy to counteract stress. And we also aimed at revealing any connection between this behavioural strategy and the cortisol response in a confinement test. To identify behavioural traits the fish were exposed to three different tests; the latency to first feeding after transfer to a new environment, latency to first attack after the introduction of an intruder and latency to first escape attempt when exposed to a decreasing oxygen saturation in the water. After these tests the fish were exposed to a confinement test and a blood sample were collected for analysis of plasma cortisol. The fish displayed a great variety of behavioural responses as well as a variety in cortisol response to the confinement stress. High and low responders could be identified within our population, but there were, however, no apparent coherence to any of the behavioural responses. In addition, there were no correlations between the behavioural responses either. We therefore conclude that there is no coherent set of behavioural and physiological stress responses in our population which is consistent over time, and that the cortisol response is not involved in determining the different behavioural responses to stress.
Degree project in Biology