Flowing right through the heart of Silicon Valley and the City of San Jose, Coyote Creek is probably not what most people would picture when thinking about habitat for steelhead (Oncorhynchus mykiss). But despite the significant change brought to the watershed through urban development, Coyote Creek is one of several streams meeting the southern end of San Francisco Bay that support steelhead populations. The fish in these urbanized streams belong to the Central California Coast Distinct Population Segment (CCC DPS), which is listed as threatened under the US Endangered Species Act.

 

As the district responsible for managing water for Santa Clara County’s 1.9 million residents, environment, and economy, Valley Water monitors sensitive species inhabiting their urbanized waterways. One of the tools used to do this is passive integrated transponder (PIT) tags. Biologists implant these tags in captured O. mykiss, release them, and then monitor strategically placed PIT antenna arrays that can detect the tagged fish as they move through different locations in the watershed. PIT tags rely on radio-frequency identification (RFID) technology, and function in much the same way as the “microchips” that are commonly implanted in pet dogs and cats. When a tagged fish swims past a PIT antenna, the energy emitted by the antenna causes the tag to transmit its unique identifying code. This information is then stored along with the date and time of detection in the memory of a PIT tag reader that is attached to the antenna.