Abstract
We investigated the relationship between telemetry measurements of heart rate and swimming activity and the physiological status in farmed Atlantic salmon (Salmo salar) to assess the potential to use telemetry measurements as proxies for stress. Sensor tags measuring heart rate and swimming activity were surgically implanted into the peritoneal cavity of Atlantic salmon individuals kept in tanks. Four tanks were stocked with three tagged fish and four untagged cohabitants, while two additional tanks containing 16 untagged fish were used as reference groups. Following surgery, tagged fish were kept undisturbed for 14 days as acclimation period. All fish were then subjected to physical stress by reducing the tank water level in 4 consecutive rounds, after which they were left undisturbed for another ten days before the experiment ended. Plasma cortisol, glucose, lactate and osmolality were measured to assess stress levels from fish in the reference groups before and after being subjected to stressing and from all fish at the end of the experiment. Both heart rate and swimming activity rose after the stress treatment, remaining elevated for 24.5 and 16.2 Hrs respectively. Glucose, plasma cortisol, lactate and osmolality levels were significantly greater when measured immediately after stress. Results from the experiment indicate that heart rate and swimming activity can be used as proxies for fish stress, thus opening the possibility for on-line stress monitoring in full scale production.
Highlights
Atlantic salmon (Salmo salar) farming is a growing global industry (Directorate of Fisheries, 2019) responding to increased global need for ocean-based protein production (Olafsen et al, 2012)
The average baseline heart rate for all fish equipped with heart rate Data Storage Tags (DSTs) (N = 12) in the 48 h prior to stressing was 24.2 beats per min (BPM) (SD = 2.3 BPM), while the average baseline swimming activity for all fish equipped with swimming activity DSTs (N = 4) before normalization was 0.48 m/s2 (SD = 0.12 m/s2)
Blood parameter levels sampled at the end of the experiment in the recovery period (March 14th) had fallen to levels similar to those at the start and pre-stressing samples (Table 1), indicating a physiological recovery. The results from this experiment demonstrate that there are changes in heart rate and swimming activity in response to stress events that are consistent with blood proxies for stress levels in Atlantic salmon
Summary
Atlantic salmon (Salmo salar) farming is a growing global industry (Directorate of Fisheries, 2019) responding to increased global need for ocean-based protein production (Olafsen et al, 2012). The industry faces challenges regarding fish welfare and is under pressure to improve production methods and farm operations. Operations involving fish handling (e.g. crowding using sweep-nets followed by pumping and treatment against sea lice (Lepeophtheirus salmonis) or disease) are common in Norwegian aquaculture and detrimental to fish welfare (Hjeltnes et al, 2018). Handling related welfare hazards are believed to be major contributors to the annual mortality in salmon production (Bleie and Skrudland, 2014). With a mortality of 14.7% for the sea stage in 2018 (Norwegian Food Safety Authority, 2018), this highlights the need for better control of how operations are conducted and their impact on fish welfare
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
