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Fish Bulletin 179 - Contributions to the Biology of Central Valley Salmonids, Volume 1 of 2
Title: Contributions to the Biology of Central Valley Salmonids, Volume 1 (PDF)
Description: The Salmonid Symposium was organized by an ad hoc committee of state and federal fishery biologists concerned with the management of Central Valley (CV) salmon and steelhead trout (Oncorhynchus spp.) populations and their habitats. It was held at Bodega Bay, California on October 22–24, 1997. Topics covered included research on various CV salmon and steelhead populations, ocean fishery management, history of upper Sacramento River hatchery operations, and steelhead management policy.
Editor: Randall L. Brown, Department of Water Resources
Download Individual Papers
- Title: Front Matter (244kb PDF)
Description: Consists of Title page, copyright, table of contents, preface, dedication, in appreciation, acknowledgements, foreward, contributing authors pages.
Editor: Randall L. Brown, Department of Water Resources
- Title: Central Valley Steelhead (553kb PDF)
Abstract: Before extensive habitat modification of the 19th and 20th centuries, steelhead (Oncorhynchus mykiss) were broadly distributed throughout the Sacramento and San Joaquin drainages. Historical run size is difficult to estimate given the paucity of data, but may have approached 1 to 2 million adults annually. By the early 1960s run size had declined to about 40,000 adults. Natural spawning populations currently exist in the Sacramento and San Joaquin river systems but at much lower levels. Coastal rainbow trout populations can be polymorphic in their life-history, and progeny of one life-history form can assume a life-history strategy different from that of their parents. A polymorphic population structure may be necessary for the longterm persistence in highly variable environments such as the Central Valley . Despite the substantial introduction of exotic stocks for hatchery production, native Central Valley steelhead may have maintained some degree of genetic integrity. Primary stressors affecting Central Valley steelhead are all related to water development and water management, and the single greatest stressor is the substantial loss of spawning and rearing habitat due to dam construction. Central Valley anadromous fish management and research is primarily focused on chinook salmon (Oncorhynchus tshawytscha) and has lead to less emphasis on steelhead monitoring and restoration. Much of the information on historical abundance and stock characteristics that exists for Central Valley steelhead is derived from an intensive Wildlife research program in the 1950s. Since this time there has been relatively little research directed at steelhead in the Central Valley , and efforts to restore Central Valley steelhead have been greatly hampered by lack of information. The National Marine Fisheries Service cited the ongoing conservation efforts of the Central Valley Project Improvement Act (CVPIA) and CALFED as justification for listing Central Valley steelhead as a threatened species under the Endangered Species Act, rather than endangered as proposed. Restoration actions identified in these programs are largely directed at chinook salmon recovery with comparatively little emphasis on specific actions needed to recover steelhead, or have not yet been implemented. The structure of rainbow trout populations has important management implications that can only be addressed through an integrated management strategy that treats all life-history forms occupying a stream as a single population. However, management agencies have generally failed to recognize this, as exemplified by the federal government's decision to exclude the non-anadromous forms in the ESA listing for steelhead, despite their recognition that they are important to the persistence of the anadromous forms. Steelhead need to be managed separately from chinook salmon stocks if recovery is to be successful, and recovery strategies must include measures to protect and restore the ecological linkages between the different life-history forms and measures to restore steelhead to some of their former habitat.
Author: Dennis R. McEwan
- Title: Applications of Population Genetics to Conservation of Chinook Salmon Diversity in the Central Valley (447kb PDF)
Description: Population genetics is playing an increasingly important role in the conservation of salmonid resources in the Pacific Northwest . The National Marine Fisheries Service considers a salmon population worthy of conservation under the U.S. Endangered Species Act if it represents an Evolutionary Significant Unit (ESU), “…a population (or group of populations) that (1) is substantially reproductively isolated from other conspecific population units, and (2) represents an important component in the evolutionary legacy of the species” (Waples 1991, 1995).
Author: D. Hedgecock, M.A. Banks, V.K. Rashbrook, C.A. Dean, and S.M. Blankenship
- Title: Historical and Present Distribution of Chinook Salmon in the Central Valley Drainage of California (595kb PDF)
Abstract: Chinook salmon (Oncorhynchus tshawytscha) formerly were highly abundant and widely distributed in virtually all the major streams of California's Central Valley drainage—encompassing the Sacramento River basin in the north and San Joaquin River basin in the south. We used information from historical narratives and ethnographic accounts, fishery records and locations of in-stream natural barriers to determine the historical distributional limits and, secondarily, to describe at least qualitatively the abundances of chinook salmon within the major salmon-producing Central Valley watersheds. Individual synopses are given for each of the larger streams that historically supported or currently support salmon runs.
In the concluding section, we compare the historical distributional limits of chinook salmon in Central Valley streams with present-day distributions to estimate the reduction of in-stream salmon habitat that has resulted from human activities—namely, primarily the construction of dams and other barriers and dewatering of stream reaches. We estimated that at least 1,057 mi (or 48%) of the stream lengths historically available to salmon have been lost from the original total of 2,183 mi in the Central Valley drainage. We included in these assessments all lengths of stream that were occupied by salmon, whether for spawning and holding or only as migration corridors. In considering only spawning and holding habitat (in other words, excluding migration corridors in the lower rivers), the proportionate reduction of the historical habitat range was far more than 48% and probably exceeded 72% because most of the former spawning and holding habitat was located in upstream reaches that are now inaccessible for salmon. Individual stream assessments revealed substantial differences among streams in the extent of salmon habitat lost. Some streams experienced little or no reduction (for example, Bear River, Mill Creek) while others were entirely eliminated from salmon production (for example, McCloud, Upper Sacramento , and Upper San Joaquin rivers.)
Author: Ronald M. Yoshiyama, Eric R. Gerstung, Frank W. Fisher, and Peter B. Moyle
- Title: Shasta Salmon Salvage Efforts: Coleman National Fish Hatchery on Battle Creek, 1895–1992 (1199kb PDF)
Description: For well over a century, Californians have sought to compensate for depleted salmon runs in the upper Sacramento River Basin by creating fish hatcheries. Beginning in 1872, fish culturalist Livingstone Stone located the West's first fish hatchery on the lower McCloud River . Between 1870 and 1960, 169 significant public and private fish hatcheries and egg collecting stations were operated throughout the state (Leitritz 1970, p 11). The fifth hatchery to be owned and managed by the US Commission of Fish and Fisheries (later renamed the US Fish Commission), was the Battle Creek Station located near Anderson.
Author: Michael Black
- Title: Factors Affecting Chinook Salmon Spawning in the Lower Feather River (345 kb PDF)
Abstract: We review the status of chinook salmon in the lower Feather River and examine factors affecting chinook salmon spawning since the construction of Oroville Dam. Spawning occurred in depths from 0.4 to 4 ft with the central 50% of observations in the 1.6 to 2.6 ft range. Depth used was slightly higher at increased flows. Velocities of 0.4 to 4.8 ft/s (central 50% = 1.5 to 2.7 ft/s) were used at all flows. Redds were constructed in substrate containing less than 60% fines in 0.2- to 1-inch to 6- to 9-inch gravel size classes.
Redd surveys showed that spawning occurred in twice as much area below Thermalito Afterbay Outlet than the low flow channel (LFC). However, in most recent years, about 75% of fish spawned in the LFC. Superimposition indices calculated from these results suggest that there was insufficient spawning area in the LFC to support the number of spawning pairs, but adequate area below Thermalito Afterbay Outlet. Spawning activity was highest in the upper three miles of the LFC, whereas spawning area was relatively evenly distributed below Thermalito Afterbay Outlet. Historical results suggest superimposition significantly reduces egg survival.
Statistical analysis of historical data showed that there has been a highly significant increase in the number of salmon spawning in the LFC. In-channel escapement explained a significant additional portion of the variability in spawning distribution. The significant increase in the proportion of spawners using the LFC over time may be at least partially attributable to an increasing proportion of river flow from this channel. Substrate composition based on Wolman counts and bulk samples do not explain trends in spawning distribution as LFC gravel has become progressively armored over the past 16 years, whereas downstream substrate composition has not changed detectably. Temperature trends were not significantly correlated with spawning distribution. We hypothesize that hatchery stocking location and genetic introgression between fall-run and spring-run chinook stocks also account for spawning activity in the LFC. Spawning simulations using an egg production model based on these statistical analyses yielded very different results than a PHABSIM instream flow model.
Author: Ted Sommer, Debbie McEwan, and Randall Brown