Species Status:

The Sacramento River winter-run Chinook salmon ESU is represented by a single extant population.  Construction of the Shasta and Keswick Dams completely displaced this ESU from its historical spawning habitat.  Cold-water releases from the reservoir behind Shasta Dam artificially maintain the remaining spawning habitat.  The productivity and abundance of the naturally spawning component of this ESU have exhibited marked improvement in recent years, compared to years of relatively low abundance in the 1980s and early 1990s.  The Biological Review Team (BRT) noted that the recent mean abundance[1] is only 3 percent of the peak mean (post-1967), and the BRT is particularly concerned about risks to the diversity and spatial structure of the ESU.  Construction of Shasta Dam merged at least four independent populations into a single population, resulting in a substantial loss of genetic diversity, life-history variability, and local adaptation.  Critically low salmon abundance (particularly in the early 1990s) imposed “bottlenecks” for the single remaining population, which further reduced genetic diversity.  ESU viability is assessed on the basis of four Viable Salmon Population (VSP) criteria: abundance, productivity, spatial structure, and diversity.  For this ESU, the BRT found extremely high risk for each of the four VSP categories, with the highest concern for spatial structure and diversity, and significant concern for abundance and productivity.  While encouraged by somewhat recent increases in abundance of the single population, the majority opinion of the BRT was that the naturally spawned component of the Sacramento River winter-run ESU is still “likely to become extinct within the foreseeable future.”

Two artificial propagation programs are also part of the Sacramento River winter-run Chinook ESU.  An artificial propagation program is continuing, and a captive broodstock program for winter-run Chinook were carried out, both at the Livingston-Stone National Fish Hatchery (NFH) on the mainstem Sacramento River above Keswick Dam.  A captive broodstock program was also maintained at the University of California’s Bodega Marine Laboratory.  These programs (operated for conservation purposes since the early 1990s) were identified as high-priority recovery actions in the 1997 Draft Recovery Plan for this ESU.  Because of increased escapement over the past several years, the captive broodstock programs have been terminated.  An assessment of the effects of these artificial propagation programs on the viability of the ESU in total concluded that the programs decrease risk to some degree by contributing to increased ESU abundance and diversity, but have a neutral or uncertain effect on productivity and spatial structure.  A second naturally spawning population is considered critical to the long-term viability of this ESU, and plans are under way (but not yet implemented) to attempt establishment of a second population in the upper Battle Creek watershed, using the artificial propagation program as a source for fish.  The artificial propagation program has contributed to maintaining diversity of the ESU through careful use of spawning protocols to maximize genetic diversity of propagated fish and minimize impacts on the naturally spawning population.  In addition, the artificial propagation and captive broodstock programs have contributed to preserving the genome of this ESU. 

Recovery Plan Status:

A draft recovery plan for the Sacramento winter-run Chinook salmon ESU was issued in August 1997.  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:          3

The recovery priority number for the Sacramento River winter-run Chinook salmon ESU was based on a high magnitude of threat due to a single extant population vulnerable to loss of genetic diversity, low abundance, unscreened diversions, high water temperatures, and effects of drought.  The recovery potential is low to moderate due to the lack of additional populations, lack of available/suitable habitat (cold water), unscreened diversions/passage problems, and inadequate instream flow. Conflict was determined to be present due to anticipated future development, habitat degradation issues, and increasing demands for Central Valley water supplies.

Priority Recovery Actions Needed:

The primary priority remaining for the winter-run Chinook salmon ESU is the establishment of an additional population or populations within the ESU.  With only one population, the effects of other remaining threats (e.g., population size, unscreened water diversions, adverse water flow and temperature conditions, passage problems at various structures, and risk from drought conditions) are exacerbated.  Reduction of all threats contributes to fulfillment of the VSP criteria for a viable ESU.  CALFED’s Battle Creek Restoration Project is another priority action to address limiting factors.  This project has already restored stream reaches in the 42 miles of Upper Battle Creek suitable for winter-run Chinook salmon.  The upper reach is to be fully restored under an agreement between Pacific Gas and Electric (which operates nine hydroelectric dams in this reach) and the resource agencies.  The intent is to remove five of the dams and dedicate water rights to the environment.  The remaining dams would have increased instream flows, resulting in a habitat increase of 500 to 800 percent.  In addition, 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.

Threats & Impacts:

As winter-run Chinook salmon historically were dependent on access to spring-fed tributaries to the upper Sacramento River that remained cool during summer and early fall, the most obvious impact to this ESU was the construction of Shasta Dam.  The dam blocked access to the ESU’s entire historic spawning habitat.  With cold-water releases from Shasta creating conditions suitable for winter-run Chinook salmon 100 feet below the dam, this species was able to survive habitat alteration, but experienced significant impacts.  Presumably, there were several independent populations of winter-run Chinook salmon in the Pitt, McCloud, and Little Sacramento Rivers, and in various tributaries to these rivers, such as Hat Creek and the Fall River.  These populations merged to form the current single population.  Any populations that may have existed in Battle Creek and the Calaveras River have since been extirpated.  This ESU continues to be threatened by having only one extant population, low population size (compared to historic levels), vulnerability to drought, inadequately screened or unscreened water diversions, predation at artificial strictures and by non-native species, pollution (e.g., Iron Mountain Mine), adverse flow conditions, high summer water temperatures, unsustainable harvest rates, and passage problems at various structures.

Conservation Actions:

Numerous conservation actions were conducted from 2004–2006 for the Sacramento River winter-run Chinook ESU.

The Central Valley Project section 7 consultations with the Bureau of Reclamation likely contributed to habitat improvements benefiting the Sacramento River winter-run Chinook salmon ESU.   Implementation of the 1992 reasonable and prudent alternative has provided substantial benefits to this ESU by improving habitat and fish passage conditions in the Sacramento River and Delta.  Such improvement likely has contributed to increases in abundance and productivity over the past decade through actions such as maintenance of minimum water flows during fall and winter months, establishment of temperature criteria to support spawning and rearing upstream of Red Bluff Diversion Dam (coupled with water releases from Shasta Dam), operation of the Red Bluff Diversion Dam gates for improved adult and juvenile fish passage, and constraints on Delta water exports to reduce impacts on juvenile outmigrants.

In addition, two large, ongoing comprehensive conservation programs in the Central Valley provide a wide range of ecosystem and species-specific protective efforts benefiting 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, and has made 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, 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 native fish, including salmon.

The CVPIA balances the priorities of fish and wildlife protection, restoration, and mitigation with 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.  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).

Harvest protective measures benefiting winter-run Chinook salmon include seasonal constraints on sport and commercial fisheries south of Point Arena.  In addition, the State has listed winter-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., management measures for time and area closures, gear restrictions, and zero bag limits in the Sacramento River).

02/20/2008