NOAA Fisheries scientists from the West Coast Region and the Southwest Fisheries Science Center recently presented their research on advanced technologies to protect and understand behavior of endangered Sacramento River winter-run Chinook salmon to an independent academic panel. Sacramento River winter-run Chinook salmon in California’s Central Valley are one of the most endangered federal marine species in the country. They were listed as threatened under the Endangered Species Act in 1989, and reclassified as endangered in 1994. The species continues to struggle to regain footing as a viable and sustainable population despite conservation efforts. NOAA Fisheries recently highlighted their fragile existence in the Agency’s new Species in the Spotlight initiative to bring even greater attention to the challenges this species faces to survive.
The science panel’s review process is part of a Delta-wide program established by NOAA Fisheries in its Biological Opinion for water operations in California’s Central Valley. This is the sixth annual meeting to provide feedback and suggestions to the Agency’s researchers.
“This panel serves a key function by ensuring we are using the best possible science for protecting and restoring winter-run Chinook salmon,” said Maria Rea, Assistant Regional Administrator for NOAA Fisheries West Coast Region, California Central Valley Office. “Their recommendations and suggestions are critical in validating our models and understanding how best to help these fish survive, especially during this severe drought.”
The NOAA Fisheries researchers shared two mathematical models with the panel as well as information on how water temperatures impacted the winter-run Chinook offspring and affected water managers’ decisions for water releases from Keswick Dam on the upper Sacramento River in 2015.
The first model, the River Assessment for Forecasting Temperature, or RAFT, is designed to provide upper Sacramento River temperatures based on water releases from Keswick Dam. Understanding and maintaining cooler water temperatures are critical for the progeny of winter-run Chinook salmon. It is estimated that only approximately 5 percent of juvenile winter-run Chinook from the 2014 run survived their migration downstream to the Red Bluff Diversion Dam, which is approximately 80 percent lower survival than the 15-year average. Water temperature is likely a major factor in the increased mortality.
The RAFT model will help water managers and operators understand how water released from Keswick Dam affect temperatures in the upper Sacramento River where the egg nests, or redds, are most vulnerable.
The second model is the Enhanced Particle Tracking Model, or ePTM. The ePTM is designed to model the potential movement of salmonids, including winter-run Chinook salmon, through the Delta to the Pacific Ocean. Understanding where these vulnerable fish may be in the Delta at any given time will help water managers modulate pumping operations to protect the smolts from water intakes and other water project effects.
“We are developing a simple yet very accurate model to answer the critical question of what happens to salmon as they swim through the Delta,” said Vamsi Krishna Sridharan, a fisheries ecologist from the NOAA Fisheries’ Southwest Fisheries Science Center. “This simple model provides valuable insight into the most important stressors faced by salmon as they migrate to the sea.”
Sacramento River winter-run Chinook are named after their river of origin and the season when they pass under the Golden Gate Bridge to return to spawn. Historically, the fish would migrate high up into the rivers that drain the southern Cascade Mountains. Summer snowmelt and cold water springs kept their eggs and offspring cool over the long hot summer. Cold water is critical for the survival of the native salmon species.
Unfortunately, these ideal cold water spawning grounds were cut off from this species when the Shasta Dam, the largest man-made dam in California, was completed in 1945. It blocked the winter-run from their historic spawning habitat and restricted them to areas in the river at lower elevations where water is typically warmer and less suitable for spawning.
Data released for 2015 indicates the number of winter-run Chinook surviving over the ongoing drought conditions will be less than that in 2014, despite the extensive efforts of several Federal and State of California agencies that have been closely coordinating on this critical conservation issue.
“I do believe all the agencies involved have pushed themselves even harder to be creative and find solutions to make every drop of water count multiple times for multiple purposes,” said Rea. “The mathematical tools our researchers are developing will continue to help us as we weather these extremely difficult conditions caused by the drought.”
LEARN MORE:
2015 Long-term Operations Biological Opinions Annual Science Review – Review Materials, Supplemental Documents, Background Information, and Presentations