Microarray-predicted marker genes indicating handling stress in maraena whitefish (Coregonus maraena)

Stress represents a major factor negatively affecting fish welfare in aquaculture. The head kidney is the effective centre for neuro-immune interactions in teleost as it is the main secretory organ of stress hormones and gathers major leukocyte populations. The present study investigated the influence of acute and long-term (chronic) handling stress in maraena whitefish. The aim was to define stress-related physiological changes in maraena whitefish using traditionally used and newly identified parameters. We determined the levels of the well-established biomarkers included triglycerides, lactate and cholesterol in blood plasma. In addition, the transcriptome of the head kidney of differently treated whitefish was recorded to identify new potential biomarkers and to investigate the relationship between immune functions and stress responses. For the acute stress approaches, the fish were first acclimatised in pairs in a tank, then the control fish was removed, killed and sampled. The remaining fish was subjected to a one-minute handling stress: The fish was captured with previously moistened nets and lifted out of the tank, placed in a bucket and then transferred back into the tank. This was done in parallel, with both fish transferred to another tank after stress, where they were kept until sampled after 3h or 24h. For the chronic stress approaches, two animals from the same treatment group (control or stress) were kept in each tank and different tanks were used for each replicate. A one minute handling stress was applied daily for 10 d. After 3 h, 24 h and 10 d, respectively, the fish were killed, measured and sampled.