Golden State Today

In California, where salmon populations are generally declining, Putah Creek offers a different narrative. This restored stream, running through the University of California, Davis campus, is witnessing an increase in wild salmon that are completing their life cycle. A study published in the journal Ecosphere has documented Putah Creek-origin salmon for the first time. Although Chinook salmon have been seen at the creek since 2014, previous studies identified them as hatchery strays. The new research confirms that some returning salmon were actually born in Putah Creek.

Andrew Rypel, senior author and director of the UC Davis Center for Watershed Sciences at the time of the study, remarked on this finding: “The fact that you have Putah Creek-origin fish is a big deal.” He noted that a stable population indicates a well-managed ecosystem and provides hope for other degraded streams.

Putah Creek faced challenges after Monticello Dam was built in the 1950s, reducing its water flow significantly. However, following a lawsuit in 2000 which led to year-round flows mandated by the Putah Creek Accord, efforts from local communities and researchers helped restore it. With water returned to the stream came insects, songbirds, and eventually salmon.

Lead author Lauren Hitt utilized otoliths from adult Chinook salmon carcasses recovered between 2016 and 2021 to trace their origins. Her findings showed that while most were hatchery-origin fish, eleven out of 407 analyzed were born in Putah Creek.

Rypel suggested this discovery could change perceptions about fish hatcheries' role in conservation: “The idea that hatcheries can be part of the solution might take people off guard.”

Salmon face numerous obstacles on their journey from Lower Putah Creek to the Pacific Ocean and back again. In 2021, atmospheric conditions led to significant setbacks when returning salmon died before spawning due to debris and ammonia-saturated waters entering the creek.

Despite these challenges, Hitt emphasized community involvement's importance: “There’s so much local love for these fish,” she said.

UC Davis continues to monitor these developments as students participate in research projects along Putah Creek. Co-authors of this study include experts from various institutions such as Norwegian Institute for Nature Research and National Marine Fisheries Service alongside several UC Davis researchers.

Funding was provided by organizations including Solano County Water Agency and Yolo Basin Foundation among others.