Species Status:

The Central Valley (CV) spring-run Chinook salmon ESU has been reduced from an estimated 17 historical populations to only three extant natural populations with consistent spawning runs (on Mill, Deer, and Butte Creeks, which are tributaries to the Sacramento River).  These remaining natural populations reached low abundance levels during the late 1980s (67 to 243 spawners compared to a historic peak of about 700,000 spawners), and are within close geographic proximity, making them vulnerable to disease and catastrophic events.  CV spring-run Chinook require cool water while they mature in freshwater over the summer.  Summer water temperatures in the CV are suitable for Chinook salmon only above the 150 to 500 meter elevation.  Most such habitat in the CV is now upstream of impassable dams.  The upper Sacramento River supports a small spring-run population, but its status is poorly documented and the degree of hybridization with fall-run Chinook salmon is unknown.  Of numerous Sierra Nevada stream populations only two remain – the Feather River and the Yuba River populations.  The Feather River population is dependent on Feather River Hatchery (FRH) production (which is considered part of the ESU) but may have hybridized with fall-run Chinook.  Production is offsite, which contributes to straying.  The status of the Yuba River population is largely unknown, other than appearing to be small.  An overall loss of diversity has resulted from the extirpation of spring-run populations in most of the CV, including all the San Joaquin tributaries.  The Biological Review Team (BRT) views the FRH as a major threat to the genetic integrity of the remaining wild spring-run comprising this ESU.

The recent 5-year mean abundance for the three naturally spawning populations remains relatively small (500 to over 4,500 spawners); however, short- and long-term productivity trends are positive and population sizes have shown continued increases over the abundance levels of the 1980s.  The BRT has noted moderately high risk for the VSP abundance, spatial structure, and diversity criteria, but a lower risk for productivity (reflecting the recent positive trends).  Informed by this risk assessment, the strong majority opinion of the BRT is that the CV spring-run Chinook salmon ESU is “likely to become endangered within the foreseeable future.”  No artificially propagated populations of spring-run Chinook in this ESU mitigate the BRT assessment.

Recovery Plan Status:

No recovery plan has been completed for this ESU.  A draft multi-species recovery plan, that includes updated information for this ESU, is under development and is expected to be completed June 2007, with a final plan expected in December of 2007.

Recovery Priority Number:          7

The recovery priority number for the CV spring-run Chinook ESU was based on a moderate magnitude of threat, due to only three remaining extant natural populations with consistent spawning that are in close geographic proximity; the lack of cool water habitat below impassable dams; and the threat to genetic integrity from the FRH.  The recovery potential is low to moderate due to lack of suitable habitat (cold water, high elevation) below impassable barriers, and the low number (three) of extant natural populations.  Conflict was determined to exist due to anticipated future development, habitat degradation issues, and increasing demands for CV water supplies

Priority Recovery Actions Needed:

Recovery of the CV spring-run Chinook salmon ESU continues to be limited by the close geographic proximity of the only three remaining wild spring-run Chinook salmon populations with consistent spawning runs, which makes them vulnerable to disease and catastrophic events, loss of spawning habitat, widespread degradation and modification of remaining habitat (especially spawning and rearing habitat), and genetic threats from the FRH.  The many small hydropower dams and water diversions on the natal tributaries reduce or eliminate instream flows during spring-run migration periods, leading to predation by non-native species and excessively high water temperatures, and loss of fish attributed to unscreened or inadequately screened water diversions in migratory corridors.   Reduction of all these threats contributes to fulfillment of the Viable Salmon Population (VSP) criteria for a viable ESU. 

CALFED’s Battle Creek Restoration Project is a priority action.  This project has already restored stream reaches in the 42 miles of Upper Battle Creek suitable for spring-run Chinook salmon.  This upper reach is to be fully restored under an agreement between Pacific Gas and Electric (which operates nine hydroelectric dams in this reach) and resource agencies.  The intent is to remove five of the dams and dedicate those water rights to the environment.  The remaining dams would have minimum instream flows increased, resulting in a habitat increase of 500 to 800 percent.  Remaining dam structures would be modified with optimally designed fish ladders and screens, and the meander belt and riparian forest would be restored.  Continued funding and implementation of CALFED’s Ecosystem Restoration Program and the CVPIA remain a priority overall to continue habitat restoration efforts, screening of diversions, flow and temperature monitoring, status and trends research monitoring, modification of structures to improve fish passage, and overall water quality improvements.

The FRH continues to influence spring-run Chinook salmon populations in the Feather and Yuba Rivers, due to straying and hybridization with (unmarked) fall-run fish.  This remains a major threat to the genetic integrity of the remaining wild spring-run Chinook populations, and thus addressing this threat remains a priority.

Threats & Impacts:

The CV spring-run Chinook salmon ESU is currently faced with three primary limiting factors and threats: (1) loss of most historic spawning habitat, (2) degradation of the remaining habitat, and (3) genetic threats from the FRH spring-run Chinook salmon program.  Spring-run Chinook require cool freshwater in summer, most of which is upstream of impassable dams.  The ESU is limited to only three natural populations of spring-run (on Mill, Deer, and Butte Creeks) that have consistent spawning runs, one small and largely unknown population on the Yuba River, and a Feather River population dependent on FRH production.  This ESU continues to be threatened by habitat loss, degradation and modification, small hydropower dams and water diversions that reduce or eliminate instream flows during migration, unscreened or inadequately screened water diversions, excessively high water temperatures, and predation by non-native species.

Conservation Actions:

During 2004–2006, progress was made in addressing some of the limiting factors and threats to this ESU, largely through ESA section 7 consultations and other ESA-related conservation efforts in the Central Valley.  The Central Valley Project section 7 consultation with the Bureau of Reclamation has likely contributed to habitat improvements benefiting the CV spring-run Chinook salmon ESU, such as flow and temperature improvements. 

In addition, two large, comprehensive conservation programs in the Central Valley provide a wide range of ecosystem and species-specific protective efforts benefiting spring-run Chinook salmon – CALFED and the Central Valley Project Improvement Act (CVPIA).   CALFED is a cooperative effort of more than 20 state and Federal agencies working with local communities to improve water quality and reliability for California’s water supplies, while making efforts to restore the San Francisco Bay-Delta.  Though not fully implemented, CALFED’s Ecosystem Restoration Program has funded projects involving habitat restoration, floodplain restoration and protection, instream and riparian habitat restoration and protection, fish screening and passage projects, research on non-native species and contaminants, research and monitoring of fishery resources, and watershed stewardship and outreach.   CALFED established the Environmental Water Account to offset losses of juvenile fish at the Delta pumps, and to provide higher instream flows in the Yuba, Stanislaus, American, and Merced Rivers to benefit salmon.

The CVPIA balances the priorities of fish and wildlife protection, restoration, and mitigation with those of irrigation, domestic water use, fish and wildlife enhancement, and power augmentation.  The Bureau of Reclamation and the U.S. Fish and Wildlife Service have conducted studies and implemented hundreds of actions, including modifications of Central Valley Project operations, management and acquisition of water for fish and wildlife needs, flow management for fish migration and passage, increased water flows, replenishment of spawning gravels, restoration of riparian habitats, and screening of water diversions.  Actions in the Sacramento River tributaries have focused on riparian and shaded riverine aquatic habitat restoration, improved access to available upstream habitat, improved instream flows, and reduced loss of juveniles at diversions, particularly for spring-run Chinook salmon and steelhead.  Habitat restoration includes water acquisition for instream flows, channel restoration and enhancement, removal of dams and blockages to migration, gravel replenishment, and construction or modifications of devices to improve instream habitat and to improve access or reduce fish mortalities during migrations (such as fish ladders and screening diversions).

The Delta Pumping Plant Fish Protection Agreement and the Tracy Fish Collection Mitigation Agreement mitigate for State Water Project and pumping plant impacts through screening of unscreened water diversions, enhanced law enforcement efforts to reduce illegal fish harvest, installation of seasonal barriers to guide fish away from undesirable spawning habitat or migration corridors, salmon habitat restoration, and removal of four dams to improve fish passage on Butte Creek for Chinook and steelhead.  Approximately one-third of the approved funding for salmon projects specifically targets spring-run Chinook salmon and steelhead in the upper Sacramento River tributaries.

Harvest protective measures benefiting spring-run Chinook salmon include seasonal constraints on sport and commercial fisheries south of Point Arena.  In addition, the State has listed spring-run Chinook under the California Endangered Species Act (CESA), and has thus established specific in-river fishing regulations and no-retention prohibitions designed to protect this ESU (e.g., fishing method restrictions, gear restrictions, bait limitations, seasonal closures, and zero bag limits), particularly in primary tributaries such as Deer, Big Chico, Mill, and Butte Creeks, which support spring-run Chinook salmon.  The California Department of Fish and Game has implemented enhanced enforcement efforts in spring-run tributaries and adult holding areas, which have significantly reduced illegal harvest.

02/20/2008