Weakened portfolio effect in a collapsed salmon population complex

2011 ◽  
Vol 68 (9) ◽  
pp. 1579-1589 ◽  
Author(s):  
Stephanie Marie Carlson ◽  
William Hallowell Satterthwaite
Keyword(s):  
River Basin ◽  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Central Valley ◽  
Salmon Population ◽  
Portfolio Effect ◽  
Positive Correlations ◽  
The Stability ◽  
Complexity Hierarchy ◽  
San Joaquin Basin

Recent research has highlighted the importance of interpopulation diversity in fostering the stability of population complexes. Here we focus on California’s recently collapsed fall-run Chinook salmon ( Oncorhynchus tshawytscha ) and ask whether portfolio effect induced buffering is observed across the complexity hierarchy from individual populations to populations within a river basin (Sacramento, San Joaquin) to the entire Central Valley. Some buffering was observed when comparing the coefficient of variation in adult returns to a given river basin with its constituent populations but not when comparing returns to the entire Central Valley with its constituent basins because of disproportionately many fish returning to the Sacramento Basin. Moreover, we report that positive correlations in population dynamics between rivers were stronger in the last 25 years of the study compared with the first 25 years. Together, these results suggest evidence of only a weak portfolio effect that has deteriorated in recent years. Nonetheless, we also report that correlations between rivers decreased significantly with distance, suggesting that some biocomplexity remains. Our results suggest that the greatest potential for strengthening the portfolio effect would come through restoration of San Joaquin Basin populations, which at low abundance currently contribute little to the overall buffering capacity despite low cross-basin correlations.

scholarly journals Weakening portfolio effect strength in a hatchery-supplemented Chinook salmon population complex

2015 ◽  
Vol 72 (12) ◽  
pp. 1860-1875 ◽  
Author(s):  
William H. Satterthwaite ◽  
Stephanie M. Carlson
Keyword(s):  
Chinook Salmon ◽  
North Pacific ◽  
Oncorhynchus Tshawytscha ◽  
Environmental Variability ◽  
Central Valley ◽  
Simultaneous Increase ◽  
Environmental Forcing ◽  
Salmon Population ◽  
Portfolio Effect ◽  
Considerable Degradation

Biocomplexity contributes to asynchronous population dynamics, buffering stock complexes in temporally variable environments, a phenomenon referred to as a “portfolio effect”. We previously revealed a weakened but persistent portfolio effect in California’s Central Valley fall-run Chinook salmon (Oncorhynchus tshawytscha), despite considerable degradation and loss of habitat. Here, we further explore the timing of changes in variability and synchrony and relate these changes to factors hypothesized to influence variability in adult abundance, including hatchery release practices and environmental variables. We found evidence for increasing synchrony among fall-run populations that coincided temporally with increased off-site hatchery releases into the estuary but not with increased North Pacific environmental variability (measured by North Pacific Gyre Oscillation), nor were common trends well explained by a suite of environmental covariates. Moreover, we did not observe a simultaneous increase in synchrony in the nearby Klamath–Trinity system, where nearly all hatchery releases are on-site. Wavelet analysis revealed that variability in production was higher and at a longer time period later in the time series, consistent with increased environmental forcing and a shift away from dynamics driven by natural spawners.

Within-river straying: sex and size influence recovery location of hatchery Chinook salmon (Oncorhynchus tshawytscha)

2020 ◽  
Vol 77 (2) ◽  
pp. 226-235 ◽  
Author(s):  
Amanda M.M. Pollock ◽  
Maryam Kamran ◽  
Andrew H. Dittman ◽  
Marc A. Johnson ◽  
David L.G. Noakes
Keyword(s):  
River Basin ◽  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Classification Tree ◽  
River System ◽  
Classification Tree Analysis ◽  
Spawning Grounds ◽  
Natural Origin ◽  
Elk River ◽  
In The Wild

Salmon straying is often defined as the failure of adults to return to their natal river system. However, straying within a river basin can be problematic if hatchery salmon do not return to their hatchery of origin and subsequently spawn in the wild with natural-origin salmon. We examined within-river straying patterns from 34 years of coded-wire tag data, representing 29 941 hatchery fall Chinook salmon (Oncorhynchus tshawytscha) in the Elk River, Oregon, USA. Using classification tree analysis, we found that females and larger salmon were more likely to be recovered on the spawning grounds than males and smaller fish. Females larger than 980 mm had a 51.6% likelihood of recovery on the spawning grounds rather than at the Elk River Hatchery. Our findings raise questions about the behavior of straying adults and implications for management of these stocks, with a focus on methods to reduce within-river straying. We recommend further studies to determine whether carcass recoveries are fully representative of hatchery salmon that stray within the Elk River basin.

Energy dynamics and growth of Chinook salmon (Oncorhynchus tshawytscha) from the Central Valley of California during the estuarine phase and first ocean year

2010 ◽  
Vol 67 (10) ◽  
pp. 1549-1565 ◽  
Author(s):  
R. Bruce MacFarlane
Keyword(s):  
San Francisco ◽  
Chinook Salmon ◽  
Climate Models ◽  
Oncorhynchus Tshawytscha ◽  
Energy Content ◽  
Central Valley ◽  
Energy Dynamics ◽  
Period Data ◽  
Energy Gains ◽  
Engraulis Mordax

The greatest rates of energy accumulation and growth in subyearling Chinook salmon ( Oncorhynchus tshawytscha ) occurred during the first month following ocean entry, supporting the importance of this critical period. Data from an 11-year study in the coastal ocean off California and the San Francisco Estuary revealed that juvenile salmon gained 3.2 kJ·day–1 and 0.8 g·day–1, representing 4.3%·day–1 and 5.2% day–1, respectively, relative to estuary exit values. Little gain in energy (0.28 kJ·day–1) or size (0.07 g·day–1) occurred in the estuary, indicating that the nursery function typically ascribed to estuaries can be deferred to initial ocean residence. Calculated northern anchovies ( Engraulis mordax ) equivalents to meet energy gains were one anchovy per day in the estuary (8% body weight·day–1) and about three per day immediately following ocean entry (15% body weight·day–1). Energy content in the estuary was positively related to higher salinity and lower freshwater outflow, whereas in the ocean, cooler temperatures, lower sea level, and greater upwelling resulted in greater gains. These results suggest that greater freshwater flows, warmer sea temperatures, and reduced or delayed upwelling, all of which are indicated by some (but not all) climate models, will likely decrease growth of juvenile Chinook salmon, leading to reduced survival.

Analysis of microsatellite DNA resolves genetic structure and diversity of chinook salmon (Oncorhynchus tshawytscha) in California’s Central Valley

2000 ◽  
Vol 57 (5) ◽  
pp. 915-927 ◽  
Author(s):  
Michael A Banks ◽  
Vanessa K Rashbrook ◽  
Marco J Calavetta ◽  
Cheryl A Dean ◽  
Dennis Hedgecock
Keyword(s):  
Genetic Structure ◽  
Chinook Salmon ◽  
Microsatellite Dna ◽  
Life Histories ◽  
Oncorhynchus Tshawytscha ◽  
Random Mating ◽  
Central Valley ◽  
Microsatellite Dna Markers ◽  
Maximum Likelihood Methods ◽  
Genetic Structure And Diversity

We use 10 microsatellite DNA markers to assess genetic diversity within and among the four runs (winter, spring, fall, and late fall) of chinook salmon (Oncorhynchus tshawytscha) in California's Central Valley. Forty-one population samples are studied, comprising naturally spawning and hatchery stocks collected from 1991 through 1997. Maximum likelihood methods are used to correct for kinship in juvenile samples and run admixture in adult samples. Through simulation, we determine the relationship between sample size and number of alleles observed at polymorphic microsatellite markers. Most samples have random-mating equilibrium proportions of single and multilocus genotypes. Temporal and spatial genetic heterogeneity is minimal among samples within subpopulations. An FST of 0.082 among subpopulations, however, indicates substantial divergence among runs. Thus, with the exception of our discovery of two distinct lineages of spring run, genetic structure accords with the diverse chinook life histories seen in the Central Valley and provides a means for discrimination of protected populations.

Can behavioral fish-guidance devices protect juvenile Chinook salmon (Oncorhynchus tshawytscha) from entrainment into unscreened water-diversion pipes?

2014 ◽  
Vol 71 (8) ◽  
pp. 1209-1219 ◽  
Author(s):  
Timothy D. Mussen ◽  
Oliver Patton ◽  
Dennis Cocherell ◽  
Ali Ercan ◽  
Hossein Bandeh ◽  
...  
Keyword(s):  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Central Valley ◽  
Large River ◽  
Water Diversion ◽  
Small Scale ◽  
Fish School ◽  
Juvenile Chinook Salmon ◽  
Juvenile Chinook ◽  
And Behavior

Entrainment through water-diversion structures is a major passage challenge for fishes in watersheds worldwide. Behavioral guidance devices may be effective in passing fish by diversion inlets, thereby decreasing entrainment without reducing water-diversion rates, but data on their effectiveness is limited. In California’s central valley, out-migrating Chinook salmon (Oncorhynchus tshawytscha) are a species at risk for entrainment through unscreened, small-scale water-diversion pipes. Therefore, we tested entrainment susceptibility and behavior of juvenile Chinook salmon in a large-river-simulation flume at a “river” velocity of 0.15 m·s–1 with a 0.46 m diameter pipe diverting water at 0.57 m3·s–1, during the day and night. Compared with control conditions (no fish deterrent devices present), mean fish entrainment increased by 61% (day) and 43% (night) when underwater strobe lights were active, decreased by 30% when using a metal vibrating (12 Hz) ring during the night, and was unaffected by velocity cap attachments. Fish entrainments started at water velocities of 0.8 m·s–1 and decreased by 54% from spring to summer, possibly resulting from decreased pipe-passage frequency and smaller fish-school sizes. Our findings suggest that substantial entrainment can occur if fish repeatedly pass within 1.5 m of active unscreened diversions, with an estimated 50% of fish lost after encountering 18 pipes in spring and 50 pipes in summer.

scholarly journals Spatial and temporal covariability in early ocean survival of Chinook salmon (Oncorhynchus tshawytscha) along the west coast of North America

2014 ◽  
Vol 71 (7) ◽  
pp. 1671-1682 ◽  
Author(s):  
D. Patrick Kilduff ◽  
Louis W. Botsford ◽  
Steven L. H. Teo
Keyword(s):  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Survival Rates ◽  
Central Valley ◽  
Vancouver Island ◽  
Regional Patterns ◽  
Migration Patterns ◽  
The Pacific ◽  
Spatial Coverage ◽  
Correlation Scale

Abstract Knowledge of the spatial and temporal extent of covariation in survival during the critical ocean entry stage will improve our understanding of how changing ocean conditions influence salmon productivity and management. We used data from the Pacific coastwide coded-wire tagging program to investigate local and regional patterns of ocean survival of Chinook salmon (Oncorhynchus tshawytscha) from the Central Valley of California to southeastern Alaska from 1980–2006. Ocean survival of fish migrating as subyearlings covaried strongly from Vancouver Island to California. Short-term correlations between adjacent regions indicated this covariability increased, beginning in the early 1990s. Chinook salmon survivals exhibited a larger spatial scale of variability (50% correlation scale: 706 km) than those reported for other northeast Pacific Ocean salmon. This scale is similar to that of environmental variables related to ecosystem productivity, such as summer upwelling (50% correlation scale: 746 km) and sea surface temperature (50% correlation scale: 500–600 km). Chinook salmon ocean survival rates from southeastern Alaska and south of Vancouver Island were not inversely correlated, in contrast to earlier observations based on catch data, but note that our data differ in temporal and spatial coverage from those studies. The increased covariability in Chinook salmon ocean survival suggests that the marine phase contributes little to the reduction in risk across populations attributable to the portfolio effect. In addition, survival of fish migrating as yearlings from the Columbia River covaried with Chinook salmon survival from the northernmost regions, consistent with our understanding of their migration patterns.

Separable Virtual Population Analysis of Pacific Salmon with Application to Marked Chinook Salmon, Oncorhynchus tshawytscha, from California's Central Valley

1987 ◽  
Vol 44 (6) ◽  
pp. 1213-1220 ◽  
Author(s):  
Robert G. Kope
Keyword(s):  
Chinook Salmon ◽  
Goodness Of Fit ◽  
Oncorhynchus Tshawytscha ◽  
Pacific Salmon ◽  
Population Analysis ◽  
Central Valley ◽  
Virtual Population Analysis ◽  
Virtual Population ◽  
California's Central Valley ◽  
California’S Central Valley

A separable virtual population analysis model is developed for Pacific salmon which utilizes aged catch and spawning escapement data. This model is applied to marked chinook salmon, Oncorhynchus tshawytscha, from California's Central Valley hatcheries using weighted least squares criteria for goodness of fit. Structural inadequacies of the model apparently produce discrepancies between predicted values and observed data that are of about the same magnitude as the observational errors in estimating the recoveries of marked fish. Some of the inadequacy of the model may be due to environmentally induced variability in population parameters, but for the marked fish used in this analysis, some of the variability is probably due to year-to-year variability in hatchery practices. From this analysis it appears that although nominal fishing effort has been relatively stable or even declining in recent years, fishing mortality has been increasing with the exception of 1983 and 1984.

scholarly journals Juvenile life-history diversity and population stability of spring Chinook salmon in the Willamette River basin, Oregon

2016 ◽  
Vol 73 (6) ◽  
pp. 921-934 ◽  
Author(s):  
R. Kirk Schroeder ◽  
Luke D. Whitman ◽  
Brian Cannon ◽  
Paul Olmsted
Keyword(s):  
Life History ◽  
River Basin ◽  
Chinook Salmon ◽  
Life Histories ◽  
Oncorhynchus Tshawytscha ◽  
Juvenile Salmon ◽  
Population Stability ◽  
Willamette River ◽  
June July ◽  
Willamette River Basin

Migratory and rearing pathways of juvenile spring Chinook salmon (Oncorhynchus tshawytscha) were documented in the Willamette River basin to identify life histories and estimate their contribution to smolt production and population stability. We identified six primary life histories that included two phenotypes for early migratory tactics: fry that migrated up to 140–200 km shortly after emergence (movers) and fish that reared for 8–16 months in natal areas (stayers). Peak emigration of juvenile salmon from the Willamette River was in June–July (subyearling smolts), March–May (yearling smolts), and November–December (considered as “autumn smolts”). Alternative migratory behaviors of juvenile salmon were associated with extensive use of diverse habitats that eventually encompassed up to 400 rkm of the basin, including tributaries in natal areas and large rivers. Juvenile salmon that reared in natal reaches and migrated as yearlings were the most prevalent life history and had the lowest temporal variability. However, the total productivity of the basin was increased by the contribution of fish with dispersive life histories, which represented over 50% of the total smolt production. Life-history diversity reduced the variability in the total smolt population by 35% over the weighted mean of individual life histories, providing evidence of a considerable portfolio effect through the asynchronous contributions of life histories. Protecting and restoring a diverse suite of connected habitats in the Willamette River basin will promote the development and expression of juvenile life histories, thereby providing stability and resilience to native salmon populations.

Emigration of age-0 chinook salmon (Oncorhynchus tshawytscha) smolts from the upper South Umpqua River basin, Oregon, U.S.A.

1999 ◽  
Vol 56 (6) ◽  
pp. 939-946 ◽  
Author(s):  
Brett B Roper ◽  
Dennis L Scarnecchia
Keyword(s):  
River Basin ◽  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Lunar Cycle ◽  
Stream Temperature ◽  
Spring Water ◽  
Day Length ◽  
The Moon ◽  
Moon Phases ◽  
Upper South

Two rotating smolt traps were used through 4 consecutive years to monitor emigrations of age-0 chinook salmon (Oncorhynchus tshawytscha) from two watersheds of the upper South Umpqua River basin, Oregon, U.S.A. The number of wild smolts moving past the mainstem South Umpqua River trap ranged from 26 455 in 1991 to less than 5000 in 1993. The number of wild smolts passing the Jackson Creek trap ranged from 13 345 in 1991 to 0 in 1993. Higher numbers of wild smolts were significantly (P = 0.003) correlated with higher numbers of prespawning adults counted in index reaches the preceding year. Timing of emigration of smolts was found to be significantly related to stream temperature (P < 0.05) and phase of the lunar cycle (P < 0.05) but not related to changes in discharge (P > 0.05). Median emigration dates, which varied over 9 weeks, were earlier when spring water temperatures were higher. On average, two thirds of yearly smolt runs occurred when the moon was either waning or new, even though these moon phases were present only about half of the time. Significantly (P < 0.05) more fish than expected emigrated past both traps when day length was increasing.

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