A new acoustic telemetry tag that identifies carrier mortality by monitoring activity level

Abstract We present a new acoustic telemetry tag capable of detecting whether its carrier stops moving for long enough to presume the organism has died, and of reporting the time elapsed since movement ceased. The tag uses existing environmental sensor technology together with an algorithm with user‐specifiable thresholds, and importantly, can separate predation events from non‐predation mortality. The objective of developing the tag was to provide a means by which mobile telemetry surveys outside of telemetry receiver grids can better determine when and how tagged animals die. Using a field test in a freshwater lake in New Brunswick, Canada, in which 18 tags were implanted into two species of salmonid fish, we demonstrate that the new tag achieves its objective as long as users select species‐ and system‐appropriate inactivity sensor thresholds during tag programming. The tag will be a valuable addition to the acoustic telemetry toolbox, and especially when mobile surveys are an important source of detection data.