New study reveals significant impact of predation on native fish populations
Press release from the Banta-Carbona Irrigation District
A groundbreaking five-year study conducted by FISHBIO and a coalition of Central Valley water agencies has uncovered a potential missing link in efforts to protect California’s declining native fish populations: predation by non-native species. A new video released by Banta-Carbona Irrigation District (Banta-Carbona), “A Startling Picture,” takes a closer look at the research that challenges many long-held beliefs about why California’s native fish are in decline.
Key Findings:
• Non-native fish dominate the lower San Joaquin River, with native species comprising less than 1% of sampled fish
• Juvenile Chinook salmon are being consumed throughout the river
• Population-level impacts to out-migrating salmon appear substantial – greater than 50% – even under ideal conditions
• Data also shows the long-held relationship between flows and salmon populations has broken down. More flows don’t equal more fish.
The study suggests that predation by non-native fish species is having a significant impact on juvenile Chinook salmon, with population-level losses exceeding 50% even under ideal conditions, and many salmon not even surviving to reach the Delta.
“We were flabbergasted that nobody had been studying non-native fish populations. We could not believe that,” said David Weisenberger, Banta-Carbona Irrigation District General Manager. “If there’s this big void in science, how can you manage anything? It’s immensely important.”
Despite recent wet winters, regulations meant to protect fish are still restricting water deliveries to cities and farms, while commercial salmon seasons had consecutive cancellations.
Call to Action:
• Expand long-term research to fully quantify predation’s impact
• Integrate predation analysis into management strategies
• Engage regulators and policymakers with new findings
“A Startling Picture,” is the sequel to Banta-Carbona’s Telly Award-winning mini-documentary “The Missing Piece,” which takes a deep dive into the role of predation in California’s waterways and the findings of this groundbreaking study.
“The more we can do to help salmon, the more we can do to help water supplies for 40 million people in California,” says David Guy, President of the Northern California Water Association.
In addition to Banta-Carbona, the research is supported by Patterson Irrigation District, San Luis Water District, and West Stanislaus Irrigation District.
For more, visit www.banta-carbona.org.
