Animal welfare in modern production systems for fish
Study 2: How are fish affected by identified welfare problems in the lab and in aquaculture?
In order for us to better understand what fish experience as unpleasant/stressful we need to study physiological response in real situations. With the use of biotelemetry it is possible to monitor multiple physiological variables and behaviors in a free swimming fish. A few so called focal animals instrumented with biotelemetry capable of measuring gastrointestinal blood flow, heart rate (ECG), swimming behaviours (from acceleration data) and temperature will be released into the large rearing pens where physiological and behavioural data will be recorded for several weeks within the gigantic school of fish. By correlating physiological measurements with adverse behaviours, we can identify and quantify the stress induced by the various stages in the pre-slaughter handling procedures (crowding and transfer), as well as during methods currently used to stun and kill rainbow trout in aquaculture. A stressful situation in a fish farm can be environmental, like high/low water temperatures or low oxygen levels or they can be anthropogenic and part of the routines at the farm. After identifying environmental and anthropogenic stressors from our focal animals we can mimic these environments/situations in the lab in order to further explore what physiological effects such stressors have on the animals.
Fig. Study 2. Biotelemetry in aquaculture. (A) Schematic picture showing the position of the implant (grey cylinder), battery pack (black cylinder) and data logger (white cylinder) placed in the abdominal cavity of a rainbow trout Oncorhynchus mykiss. (B) The blood flow probe positioned on the celiacomesenteric artery (enlarged) and the two ECG-electrodes.