Ronald M. Yoshiyama

Historical Abundance and Decline of Chinook Salmon in the Central Valley Region of California

Abstract 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 firs...

Historical Decline and Current Status of Coho Salmon in California

Abstract The southernmost populations of coho salmon Oncorhynchus kisutch occur in California where native coho stocks have declined or disappeared from all streams in which they were historically recorded. Coho salmon previously occurred in as many as 582 streams, from the Smith River near the Oregon border to the San Lorenzo River on the central coast. Information on the recent presence or absence of coho salmon was available for only 248 (43%) of those streams. Of these 248 streams, 54% still contained coho salmon and 46% did not. The farther south a stream is located, the more likely it is to have lost its coho salmon population. We estimate that the total number of adult coho salmon entering California streams in 1987–1991 averaged around 31,000 fish per year, with hatchery populations making up 57% of this total. Thus, about 13,000 nonhatchery coho salmon have been spawning in California streams each year since 1987, an estimate that includes naturalized stocks containing about 9,000 fish of recent ...

Protection of Aquatic Biodiversity in California: A Five-tiered Approach

Abstract Aquatic biodiversity is being lost at an even more rapid rate than terrestrial biodiversity, especially in arid regions such as California. In the United States, it is increasingly obvious that the Endangered Species Act of 1973 (ESA) cannot adequately deal with this loss. To help solve this problem, we have developed a five-tiered approach for aquatic conservation in California that should be applicable to other regions as well: (1) immediate ESA listing of species likely to be extirpated in the next 20 years; (2) implementation of restoration-oriented management strategies for clusters of declining species that inhabit the same habitats or drainages; (3) creation of a system of drainages and habitats called Aquatic Diversity Management Areas that provides systematic, statewide protection of aquatic biodiversity; (4) designation of a system of key watersheds, starting with seven pilot watershed projects that represent a diversity of challenges; and (5) development of schemes for bioregional land...

Rocky intertidal fish communities of California: temporal and spatial variation

SynopsisWe 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). Eel-shaped 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.

Chinook Salmon in the California Central Valley: An Assessment

Abstract 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 chino...

Differential propensities for aerial emergence in intertidal sculpins (Teleostei; Cottidae)

Intertidal sculpins (Cottidae) subjected to progressive aquatic hypoxia in the laboratory showed interspecific differences in the time it took them to emerge from water, either partially or fully, to breathe air. Oligocottus maculosus Girard and Ascelichthys rhodorus Jordan and Gilbert were significantly less inclined than O. snyderi Greeley to emerge, while there was no observed difference between O. snyderi and Clinocottus globiceps (Girard). All four species were previously reported to be capable of respiring aerially. The different propensities of these species to emerge from water match their relative physiological capabilities for aerial respiration. Intertidal sculpins generally appear reluctant to emerge under experimental conditions, except for respiratory necessity. Such amphibious behavior and aerial respiration have apparent survival value because tidepools commonly undergo periodic hypoxia.

A History of Salmon and People in the Central Valley Region of California

Chinook salmon (Oncorhynchus tshawytscha) formerly occurred in great abundance within the California Central Valley drainage and were a correspondingly important part of the subsistence economics a...

Geographical patterns of allozymic variation in three species of intertidal sculpins

SynopsisWe examined spatial patterns of allozyme variation in three species of intertidal cottids to evaluate how much gene flow occurs between geographically separate populations (most likely via passive dispersal of planktonic larvae by currents). Our results from the analysis of geographical patterns of allele frequencies and, to some extent, from comparison of allele frequencies between newly recruited young and older resident fish are consistent with the notion that sufficient gene flow occurs in these fishes to prevent significant genetic isolation of populations. From these results, we visualize evolutionary changes in populations of these species as occurring most likely over a broad geographic scale, affecting spatially separated but genetically linked populations concurrently, rather than operating independently in individual, genetically isolated populations.

TEMPORAL STABILITY OF LACTATE DEHYDROGENASE-A CLINES OF THE HIGH COCKSCOMB, ANOPLARCHUS PURPURESCENS

In marine species with planktonic larval stages, strong geographic differentiation among resident adult populations is noteworthy in that identification of the forces and mechanisms which create such local differentiation allows an assessment of the relative importance of natural selection in promoting genetic divergence. Williams et al. (1973), and later Koehn and Williams (1978), focused on this problem in their analysis of genetic differentiation in the American eel, Anguilla rostrata. Their study centered on the interaction between age-dependent differentiation (elvers vs. resident adults) and spatial differentiation of groups along a latitudinal transect. They found different patterns of differentiation which depended upon the specific genetic marker under analysis. At the Mdh locus, allele frequencies were homogeneous among age-groups and among localities, suggesting recruitment of elvers from a common zygotic pool with no subsequent divergence between groups of colonists in situ. In contrast, at the Sdh locus, they observed a significant spatial component of variation across latitude, but one which was equally pronounced in both age groups. This result suggested (in light of the life history of the American eel) that divergence occurred prior to larval recruitment and was not further accentuated in situ. Finally, at the Phi-II locus, they observed that allele frequencies of newly recruited larvae were uniform across the transect (once again suggesting a common zygotic pool), but that geographic differentiation of adults was significant. This latter pattern would be consistent with a predominant role of local selective factors in promoting genetic divergence and it suggested selection intensities of about 10% per generation. Although the power of their analysis lies largely in the peculiar migrational history of the American eel, there is no reason to believe that the differences in genetic composition between life stages observed by Williams et al. (1973) and Koehn and Williams (1978) are in any way unique to Anguilla. As they point out, it is reasonable to expect that age-specific selection would operate in other species with planktonic larvae, but similar analyses have been rarely conducted. Actually, the degree of geographic differentiation in the American eel is rather slight; for example, systematic variation in Phi-II allele frequencies is on the order of 5% per degree of latitude (Koehn and Williams, 1978). In other marine fishes with planktonic larvae, more pronounced examples of geographic variation are known. In Anoplarchus purpurescens, an intertidal blennioid fish of the northwestern Pacific Ocean, relatively sharp differences in allele frequency over short distances have been reported (Johnson, 1971, 1977; Sassaman and Yoshiyama, 1979; Yoshiyama and Sassaman, unpubl.). Here we explore temporal (age-group) aspects of allele-frequency variation along two pronounced gradients of gene-frequency change in Anoplarchus. Our analysis follows the same logical format of Williams et al. (1973) and Koehn and Williams (1978). In addition we examine yearto-year stability of these gene-frequency clines by reference to previously published information (Johnson, 1971; Sassaman and Yoshiyama, 1979) for the same sampling sites. Since the presumption of extensive

Coho salmon are native south of san francisco bay : A reexamination of north american coho salmon's southern range limit

Abstract Kaczynski and Alvarado (2006) have challenged the established southern boundary of coho salmon ( Oncorhynchus kisutch ) at the San Lorenzo River. They conclude that it is improbable coho salmon maintained self-sustaining populations south of San Francisco Bay, based primarily on evidence from early museum collections and literature, the archaeological record, analyses of ocean conditions, and suitability of habitat. They suggest that hatchery plantings were the source of these coho salmon south of San Francisco Bay. Using the same and new information, we are able to counter these statements. Our examination of existing records found no reason to discount the coho salmon collections made in 1895 from streams south of San Francisco. Early distributional records state that coho salmon were abundant from San Francisco northward, but did not indicate coho salmon were absent south of San Francisco. Recent archeological evidence documents the presence of coho salmon in middens south of San Francisco pri...