The California Department of Fish and Wildlife (CDFW) has completed the release of approximately 23 million fall-run Chinook salmon raised at its four Central Valley anadromous fish hatcheries, the Feather River Fish Hatchery, the Nimbus Fish Hatchery, the Mokelumne River Fish Hatchery and the Merced River Hatchery.
The 23 million salmon raised and released by CDFW in 2023 represents a 15 percent increase over the roughly 20 million fall-run Chinook salmon raised and released in 2022. This year’s production goals were increased as a coordinated effort among state and federal partnering agencies to help fall-run Chinook salmon overcome impacts from an extended drought that increased water temperatures and decreased water flow throughout the Central Valley during critical salmon spawning and rearing periods. Drought conditions coupled with Thiamine Deficiency Complex, a vitamin deficiency that impacts reproduction, have reduced in-river spawning success the past several years.
Beyond the hatchery production increase, CDFW carried out several new, innovative and experimental release strategies to take advantage of some of the best in-river flows and water conditions in years and to increase overall survival.
This year, for the first time since 2020, CDFW conducted in-river salmon releases within the Feather River and the American River to take advantage of the increased water flows associated with winter storms that lingered into the spring. These flows increased available rearing habitat and provided for increased survival while migrating toward the ocean. Salmon smolts outfitted with acoustic tags were released with larger groups in their natal rivers to allow CDFW to monitor and track their downstream migration to the ocean. Preliminary results suggest high survival for groups of hatchery-raised fish released into the river systems in 2023.
The more than one million salmon fry released into the American River in February represented CDFW’s initial effort with “Parentage Based Tagging” or PBT. These juvenile salmon don’t carry physical markings or tags, but their genetic signatures have been recorded and stored for future analysis to evaluate the overall success of the fry release.
The Feather River Fish Hatchery released smaller juvenile fall-run Chinook salmon earlier in the spring than the typical smolt releases to diversify hatchery release strategies as well as the timing and size of hatchery-raised fish entering into the bay and marine environments.
CDFW added to the release sites and strategies used within San Francisco and San Pablo bays. These included new release locations at: the Estuary and Ocean Science Center in partnership with San Francisco State University; Point San Quentin, in partnership with the Marin Rod and Gun Club; and Brickyard Cove in Richmond in partnership with the City of Richmond and the Golden Gate Salmon Association. At these locations, smolts were released at night on strong outgoing tides to reduce bird predation and encourage seaward migration.
With the exception of PBT release groups in the American River, 25 percent of all fall-run Chinook salmon raised and released by CDFW’s Central Valley anadromous fish hatcheries carry coded-wire tags (CWT) with information on their origin and have a clipped adipose fin to indicate their hatchery origin. Both CWT and PBT tagged fish will provide important scientific data that will inform future management decisions and hatchery operations.
Fall-run Chinook salmon support the bulk of California’s commercial and recreational salmon fishing seasons. Although ocean and in-river salmon fishing seasons have been closed for 2023, fishing seasons will be reevaluated in 2024.