Laboratory and Field Experimental Validation of Two Different Predation Sensors for Instrumenting Acoustic Transmitters in Fisheries Research

• Published in: Fisheries
• Main Authors: Lennox, Robert J., Nilsen, Cecilie I., Nash, Ainslie, Hanssen, Erlend M., Johannesen, Hilde L., Berhe, Saron, Barlaup, Bjørn, Wiik Vollset, Knut
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2021
• Subjects: Atlantic salmon; Salmo salar
• Online Access: http://dx.doi.org/10.1002/fsh.10669; https://onlinelibrary.wiley.com/doi/pdf/10.1002/fsh.10669; https://onlinelibrary.wiley.com/doi/full-xml/10.1002/fsh.10669; https://afspubs.onlinelibrary.wiley.com/doi/pdf/10.1002/fsh.10669

We validated the performance of two types of predation sensors on acoustic telemetry transmitters in a combined field and laboratory study design using juvenile Atlantic Salmon Salmo salar and a predator large Brown Trout Salmo trutta . One tag model was outfitted with an acid‐sensitive predation sensor, and the other was equipped with a tilt‐based orientation sensor. We found similar response times for the two tag types to identify a predation event (time between known ingestion of a tagged fish and triggering of the predation sensor). However, the orientation sensor model was more accurate in laboratory trials, correctly identifying 100% of events in which predators were fed the tagged fish, whereas correct identification of predation events was 50% for the acid‐sensitive sensor in similar trials. The acid‐sensitive tags were smaller (0.65 g in air), and all 10 were eventually expelled by predators in the laboratory (2–22 d after tag ingestion). By contrast, only two of five tags with orientation sensors (1.4 g in air) were expelled in a similar period (13 and 16 d after tag ingestion). Both tags had distinct benefits: acid‐sensitive sensor tags were very small, and orientation sensor tags were seemingly more accurate and transmitted raw orientation data to receivers for postprocessing.