Use of PIT Tags for Monitoring Salmon

As an alternative to conventional monitoring methods, our biologists are taking advantage of advances in technology, using tiny devices called Passive Integrated Transponders, or PIT tags. About the size of a grain of rice, these electronic, battery-free tags are similar to the tags installed in dogs and cats by veterinarians to track lost pets. Each tag contains a unique code. When a tag passes by an antenna’s electrical field, a transceiver detects and stores the unique PIT tag number and the time that the tagged fish passed through the field. PIT tags allows us to identify and track individual fish from their release as juveniles to their return as adults. 

Prior to being released into streams, 4 to 5 month-old program coho are weighed, measured, and PIT-tagged by our partners at the Warm Springs Fish Hatchery. Information about each fish, including age, size at release, and release stream and season, is carefully recorded.

At different intervals throughout the year, we operate a total of 16 PIT tag antennas on six streams: Dutch Bill Creek, Green Valley Creek, Mill Creek, Felta Creek, Palmer Creek, and Grape Creek. During the summer months, we conduct PIT tag wanding surveys  on four streams: Dutch Bill Creek, Green Valley Creek, Mill Creek, and Grape Creek. The Sonoma County Water Agency also contributes data from their antenna sites on the Russian River mainstem and some of the larger tributaries to our PIT tag study.