The Thelma Biotel mortality sensor can measure mortality events in tagged animals using orientation technology. Mortality data where the predator exhibits similar behavior to the tagged animal can create bias without knowing what animal the data belongs to. The sensor calculates an average orientation as a baseline from tilt data received every minute. When a loss of orientation is detected, the fish ID will increase from ID to ID+1. In the validation study by Lennox et al., 2021, our orientation-sensitive sensor (mortality) identified a 100% accuracy in the laboratory trial (DOI: 10.1002/fsh.10669).
Combining the mortality sensor with either the temperature or the depth sensor can provide further data to support the study at hand. Combining with the temperature sensor could determine if a mammal ate the tagged animal, or combining with a depth sensor could reveal diel vertical migration behavior.
The mortality sensor is currently available in the tag sizes 6, 13, and 16 mm.