Development of a Head-Mounted Satellite-Linked PIT Tag Reader for Seals and Sea Lions

Biologists speculate that an increased population of harbor seals feeding on salmon smolts may have caused the observed decline in Chinook and Coho abundance in the Salish Sea. Passive Integrated Transponders (PIT tags) are often implanted in juvenile salmonids and used for population tracking, however they also provide a unique opportunity to assess the level of smolt predation by seals. We have designed and built a prototype that contains electronics capable of identifying and logging PIT tags ingested by seals, and transmitting this information to a satellite. This prototype is battery powered and designed to be suitable for head-mounting to a harbor seal. Phase I feasibility testing aimed to determine the capabilities of the prototype on captive harbor seals. The information gained will be used to determine the necessary RFID sampling rate/power consumption and guide the development of a field-ready instrument. The final prototype will be capable of logging the time and identification numbers of seal-ingested PIT tags, with the ability to transmit that information via the AROGS satellite network. From those data, researchers will be able to accurately estimate smolt predation rates, and identify which individual stock is impacted by seal predation based on ingested PIT tag IDs.