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Add To Calendar 23/02/2016 16:00:0023/02/2016 16:20:00America/ChicagoAquaculture 2016BIOTELEMETRY AS A TOOL TO IMPROVE FISH WELFARE IN AQUACULTURE Versailles 2The World Aquaculture Societyjohnc@was.orgfalseanrl65yqlzh3g1q0dme13067DD/MM/YYYY


Albin Gräns*, Erik Sandblom, Henrik Sundh, Charlotte Berg, Kristina Sundell, Michael Axelsson.
*Department of  Animal Environment and Health Swedish
University of Agricultural Sciencens, Sweden

Measuring physiological variables with the use of biotelemetry systems and data storage tags is becoming increasingly important in physiological research. This is because there are significant benefits to both the quality of the data obtained and the overall health and welfare of the animals when they are not confined by the measuring techniques used. With recent findings of a link between increased mortality after an acute stressor in fish that have a history of chronic stress, indicators and recording techniques of sub-lethal stress in free ranging fish in aquaculture has attracted an increased interest. Highly stressful events such as crowding, netting, sorting and transports are today "part of life" for the animals in a commercial fish farm and it has been argued that these events are unavoidable from a practical point of view. Nevertheless, high levels of mortality following such stressful events are devastating as they are obvious signs of processes involving deteriorated fish welfare and also cause large financial loss for the producer.

In our project we aim to use enhanced welfare as a mean to preserve the innate stress resilience of fish. This can be achieved by detecting and alleviating sub-lethal chronic stressors that occur during the normal practice regimes. To achieve this, we use two novel systems capable of measuring secondary stress responses in free swimming fish, including a data logger that can store timed recordings of heart rate and temperature for up to 3.5 months and a multivariable biotelemetry implant that can measure ECG, blood flow, heart rate and temperature continuously for 2-3 weeks. While both systems require surgical implantation into the abdominal cavity of the fish, the fish can be released back into the group after a recovery period without noticeable constraints.

A range of tests have been performed in rainbow trout to evaluate how these systems can be used to identify and quantify different stressors in an aquaculture setting. Our initial results show that resting heart rate can be used as an indicator of chronic stress as it strongly correlates with plasma cortisol levels  (R2=0.86). Furthermore, a 60 s air exposure was found to elicit a significantly greater heart rate response compared to 5 min of exhaustive exercise (69±3 vs 65±3 bpm, respectively). However, mixing fish into new social groups elicited an even greater maximum heart rate response (83±4 bpm). These results show that heart rate logging of free swimming fish have great potential as a means to detect and quantify the severity of different types of known and unknown aquaculture related stressors. Furthermore, we show that gut blood flow is an effective and sensitive indicator of acute stress as it is extremely sensitive to even minute disturbances in the surrounding environment. These initial results constitute a promising first evaluation of how biotelemetry systems and data storage tags can be used to assess and compare stressful events and by reducing those, improve fish welfare in aquaculture.

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