The Central Valley drainage of California formerly produced immense numbers of chinook salmon Oncorhynchus tshawytscha. Four seasonal runs occur in this system—fall, late‐fall, winter, and spring runs. Differences in life history timing and spatial distribution enabled the four runs to use the drainage to the fullest possible extent and once made it one of the richest regions in the world for chinook salmon production. Native American fishers within the Central Valley drainage harvested chinook salmon at estimated levels that reached 8.5 million pounds or more annually. Native harvests, therefore, were roughly comparable to the peak commercial harvests taken later by Euro‐American fishers, but whether or not native fishing depressed the productive capacities of the salmon populations to any substantial degree is not known. The commercial chinook salmon fishery in California started about 1850 in the San Francisco Bay and Sacramento–San Joaquin Delta region, where it formed the nucleus of the first major fishery conducted by Euro‐American immigrants in the state. This fishery was one of the important early industries that supported the Euro‐American settlement of the Central Valley region. The salmon fishery remained centered there until the early 1900s, when ocean salmon fishing began to expand and eventually came to dominate the fishery. Annual catches by the early Sacramento–San Joaquin in‐river fishery commonly reached 4–10 million pounds and generally were higher than the total statewide catches made during the most recent several decades. The historical abundances of Central Valley chinook salmon before large‐scale commercial exploitation and depletion of the runs cannot be determined with certainty. However, on the basis of early commercial catch records, the maximal production levels of the Central Valley chinook salmon stocks in aggregate may be conservatively estimated to have reached approximately 1–2 million spawners annually. Although substantial investment has been made by the state of California in managing the chinook salmon resource since the early years of the commercial fishery, chinook salmon have declined over the decades to small fractions of their previous numbers. The decline of the Central Valley chinook salmon resource was caused by several factors: overfishing, blockage and degradation of streams by mining activities, and reduction of salmon habitat and streamflows by dams and water diversions. Differences between the four chinook salmon runs in life history timing and habitat requirements partly account for their different population histories; the winter run is now threatened with extinction, the spring run recently has approached a similarly imperiled state, and the late‐fall run has been at moderately low population levels for the past two decades. Only the fall run, in aggregate, can be regarded as secure, but it too has undergone substantial reductions in abundance. Fall‐run spawner numbers were especially low in the San Joaquin River basin in recent years, and in Sacramen...

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SynopsisDistribution patterns and relative abundances were determined for rocky intertidal fishes in central California. Distributions were described relative to a categorization scheme of tidepools based on certain biotic and physical criteria. The fishes displayed a variety of distributions over tidepool categories and showed some segregation within categories.Cottids were the predominant tidepool fishes encountered, with Oligocottus snyderi and Clinocottus analis comprising 62% of all captures. The cebidichthyid Cebidichthys violaceus and the stichaeid Anoplarchus purpurescens were also relatively common and dominated the out-of-water microhabitat. Oligocottus snyderi showed a minor shift in distribution over tidepool categories between seasons, and C. analis showed none, but both species varied substantially in abundance. Temporal changes in abundance of the more common species indicated seasonal trends, but the duration of the census period was insuflicient to verify this.It is concluded that while species interactions may have influenced the observed patterns of habitat partitioning, the roles of predation and competition cannot be unambiguously defined. Presently, neither these nor historical factors can be discounted from having significantly influenced the evolution of the intertidal fish community.

We examined data from our own and published collections of intertidal and shallow littoral fishes of the North American Pacific Coast with respect to temporal and spatial trends in species composition and dominance. We compared (1) recent and past intertidal collections made five and seven years apart, respectively, for two California localities, (2) intertidal collections from twelve localities in California, Oregon, and British Columbia, and (3) intertidal versus subtidal collections at one California locality. Temporal comparisons indicated substantially lower abundance of the cottid Oligocottus snyderi at two California localities during 1984, at one locality due to depressed abundance of young. Interannual differences in abundances suggested that other tidepool fish assemblages undergo significant changes as well. Geographical comparisons indicated general similarity in species composition, with cottids predominating in tidepools although several other families also were well represented (e.g., Stichaeidae, Scorpaenidae). Eelshaped stichaeids and pholids occurred at high densities in exposed boulder fields. Both the tidepool and boulder field assemblages showed north-south changes in species abundances. Comparison of collections from the intertidal and subtidal zones at one California locality demonstrated that fishes of these habitats form two essentially distinct assemblages, with most species restricted to or concentrated in one or the other habitat.

This paper summarizes information on recent historical distribution and abundance of chinook salmon in the California Central Valley drainage, focusing on the period from the 1950s to today. Most of the principal Central Valley streams that historically supported salmon runs still do so, but nearly half of them have lost at least one seasonal salmon run and several major streams have had all their salmon runs extirpated. Overall abundance of chinook salmon in the Central Valley system has decreased to less than 75% of their number in the 1950s. Fall‐run chinook salmon in the Sacramento River basin compose by far the most abundant Central Valley stocks, but they substantially declined between 1953–1966 and 1967–1991. Fall‐run chinook salmon stocks in the San Joaquin River basin and Sacramento‐San Joaquin Delta tributaries showed various changes between 1953–1966 and 1967–1991 but altogether constitute only a minor portion (now 4%) of the total Central Valley spawning escapements. Three other chinook salmon runs (winter, spring, late‐fall) have shown much more pronounced reductions in recent decades. Central Valley salmon have been heavily supported by hatchery production, but the effects of hatcheries on natural stocks remain poorly understood. Major efforts are underway to restore regional chinook salmon and steelhead stocks, several of which are listed under both California and U.S. endangered species statutes.