AbstractWhile physiological stress in fish can be assessed by several laboratory‐based methods, many of those methods use very sensitive and expensive instruments, which make them impracticable under field conditions. The objective of this study was to determine the feasibility of detecting stressed states in fish, under Held conditions, using simple but reliable methods. The first set of experiments were conducted in the laboratory, where a standard handling stressor was applied to juvenile coho salmon,Oncorhynchus kisutch(Walbaum). Results of blood samples analysed by both laboratory‐based and portable methods (e.g. glucometers for diabetic patients) were in good agreement. The second set of experiments focused on field‐testing the most promising methods based on the laboratatory tests. Production lots of Atlantic salmon.Salmo salarL., at commercial fish farms were sampled to assess stress and health status with the selected field techniques, from the swim‐up to smolting stages. The measured variables included: blood glucose, protein, haemoglobin concentrations: haematocrit: erythrocyte and lymphocyte numbers: and an autopsy‐based health profile, which involved the internal and external examination of the body for texture and colour. In addition to establishing resting, or normal, values for each variable under field conditions, blood glucose levels were observed to increase significantly at 4 h after a stressful event (e.g. grading, handling) using these field methods. Some of these field techniques were found to be reliable indicators of stress in fish and have potential for use in aquaculture facilities and field monitoring p
展开▼
