Temporal variation in synchrony among chinook salmon (Oncorhynchus tshawytscha) redd counts from a wilderness area in central Idaho

2003 ◽  
Vol 60 (7) ◽  
pp. 840-848 ◽  
Author(s):  
Daniel J Isaak ◽  
Russell F Thurow ◽  
Bruce E Rieman ◽  
Jason B Dunham
Keyword(s):  
Chinook Salmon ◽  
Large Scale ◽  
Oncorhynchus Tshawytscha ◽  
Structured Populations ◽  
Strongly Correlated ◽  
Wilderness Area ◽  
Large Scale Disturbance ◽  
Stochastic Events ◽  
Central Idaho

Metapopulation dynamics have emerged as a key consideration in conservation planning for salmonid fishes. Implicit to many models of spatially structured populations is a degree of synchrony, or correlation, among populations. We used a spatially and temporally extensive database of chinook salmon (Oncorhynchus tshawytscha) redd counts from a wilderness area in central Idaho to examine patterns in synchrony as these fish underwent a sixfold decrease in abundance. Our results suggested that populations became strongly synchronous as abundances decreased and that the range, or diversity of correlations, exhibited among populations also decreased. These changes indicate that the likelihood of simultaneous extirpations has increased, which could have long-term detrimental consequences for metapopulation persistence. Implications for management are that the resilience of many metapopulations to large-scale disturbance and anthropogenic suppression may not depend solely on attempts to maintain large and productive component populations, but also on efforts to desynchronize populations that have become strongly correlated. Such efforts could entail promoting the existence of a broad distribution and diversity of habitats that support a wide array of life-history forms and ensuring that some habitats are sufficiently spatially disjunct so that risks from catastrophic stochastic events are minimized.

scholarly journals Population Trends for Chinook and Summer Chum Salmon in Two Yukon River Tributaries in Alaska

2020 ◽  
Author(s):  
Randy J. Brown ◽  
Catherine Bradley ◽  
Jeffery L. Melegari
Keyword(s):  
Chinook Salmon ◽  
Chum Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Demographic Data ◽  
Main Stem ◽  
Strongly Correlated ◽  
Yukon River ◽  
Over Time ◽  
Run Timing

Abstract An essential management objective of the Yukon Delta and Koyukuk National Wildlife Refuges in Alaska is to conserve fish and wildlife populations and habitats in their natural diversity. In keeping with this objective, the U.S. Fish and Wildlife Service installed weirs in two tributaries of the Yukon River, the East Fork Andreafsky and Gisasa rivers, in 1994 to collect information on salmon populations that used them. The weirs have been in operation for >23 y. Chinook Oncorhynchus tshawytscha and summer Chum Salmon O. keta were counted and sampled for various demographic data each year as they migrated through the weirs to upstream spawning areas. Here we examine this record of population data to describe and compare long-term variation in run abundance, run timing, length and age structure, sex composition, and production for these salmon populations. Fishery managers often look to multiple monitoring projects in-season seeking corroboration of observed run qualities; therefore, we also considered whether Yukon River main-stem indicators of abundance were correlated with these tributary escapements. Our analyses suggest long-term stability of these populations despite large annual variations in most metrics we examined. Annual escapements have varied by factors of 3–5 for Chinook Salmon and >23 for summer Chum Salmon, yet only the Chinook Salmon population in the Gisasa River appears to be declining. Main-stem abundance indicators were not correlated with Chinook Salmon escapements but were strongly correlated with summer Chum Salmon escapements. Run timing has varied annually by as much as a week earlier or later than average for all four populations with no trend over time. Mean age of the Chinook Salmon populations declined over time but remained stable for the summer Chum Salmon populations. Chinook Salmon populations in the East Fork Andreafsky and Gisasa rivers averaged 35% and 28% female, respectively. Both summer Chum Salmon populations averaged close to 50% female. Length at age has been stable or slightly declining for all four populations. Production over time was strongly correlated within species for populations in the two rivers, and averaged >1 recruit/spawner for all populations except Chinook Salmon from the Gisasa River. We discuss these findings in the context of major changes in the fishery and the environments these populations experience.

Unnatural random mating policies select for younger age at maturity in hatchery Chinook salmon (Oncorhynchus tshawytscha) populations

2009 ◽  
Vol 66 (9) ◽  
pp. 1505-1521 ◽  
Author(s):  
David G. Hankin ◽  
Jacqueline Fitzgibbons ◽  
Yaming Chen
Keyword(s):  
Chinook Salmon ◽  
Large Scale ◽  
Oncorhynchus Tshawytscha ◽  
Random Mating ◽  
Age At Maturity ◽  
Natural Spawning ◽  
Younger Age ◽  
Selection For ◽  
Age And Sex

We explored the long-term consequences of three mating regimes ((1) completely random, (2) completely random but excluding jacks (age 2 males), and (3) male length ≥ female length) on age and sex structure of wild and hatchery populations of Chinook salmon ( Oncorhynchus tshawytscha ). Regimes similar to regimes 1 or 2 are used at most salmon hatcheries, whereas regime 3 emulates the outcomes of natural spawning behaviors that favor larger males. Inheritance of age at maturity is captured in age- and sex-structured models via matrices of age- and sex-specific conditional maturation probabilities that depend on age and sex of parents. In unexploited populations, regime 1 leads to substantial long-term selection for younger age at maturity, an effect that is somewhat reduced by regime 2, but greatly reduced under regime 3. Equilibrium age and sex structures for wild and hatchery populations under regime 3 are similar to those of natural populations, whereas mating regime 1 generates age structure that is greatly shifted toward younger ages and jacks. To prevent unintentional selection for younger age at maturity, we recommend that large-scale hatcheries replace unnatural completely random mating regimes with mating regimes that emulate the outcomes of natural spawning behaviors.

In a warming river, natural-origin Chinook salmon spawn later but hatchery-origin conspecifics do not

2021 ◽  
Vol 78 (1) ◽  
pp. 68-77
Author(s):  
Catherine S. Austin ◽  
Timothy E. Essington ◽  
Thomas P. Quinn
Keyword(s):  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
River System ◽  
Local Environment ◽  
Washington State ◽  
Human Intervention ◽  
Timing Of Reproduction ◽  
Natural Origin ◽  
Skagit River

Median timing of reproduction in salmonid populations is generally consistent among years, reflecting long-term patterns of natural selection from characteristics of the local environment. However, altered selection from factors related to climate change or human intervention might shift timing over generations, with implications for the population’s persistence. To study these processes, we modeled median timing of redd (nest) counts as an index of spawning timing by natural-origin Chinook salmon (Oncorhynchus tshawytscha) in the Skagit River system in Washington State, USA. Over the last 2–6 decades, natural-origin salmon have been spawning later by 0.03–0.52 days·year–1, while a naturally spawning group that is influenced by strays from a hatchery has been spawning earlier by 0.19 days·year–1. Trends in the spawning timing of hatchery-origin strays may reflect opposing selection from the hatchery, where egg take for propagation has become earlier by 0.58 days·year–1. As mean August river temperatures have risen over the period of record, hatchery timing trends may be moving in the opposite direction from the plastic or adaptive patterns expressed by natural-origin fish.

scholarly journals Phenotypic integration of behavioural and physiological traits is related to variation in growth among stocks of Chinook salmon

2018 ◽  
Vol 75 (12) ◽  
pp. 2271-2279 ◽  
Author(s):  
Mitchel G.E. Dender ◽  
Pauline M. Capelle ◽  
Oliver P. Love ◽  
Daniel D. Heath ◽  
John W. Heath ◽  
...  
Keyword(s):  
Chinook Salmon ◽  
Large Scale ◽  
Oncorhynchus Tshawytscha ◽  
Fish Growth ◽  
Life History Stage ◽  
Diel Variation ◽  
Level Variation ◽  
Stock Level ◽  
Performance Metric ◽  
Selection For

The selection for a single organismal trait like growth in breeding programs of farmed aquaculture species can counterintuitively lead to lowered harvestable biomass. We outbred a domesticated aquaculture stock of Chinook salmon (Oncorhynchus tshawytscha (Walbaum in Artedi, 1792)) with seven wild stocks from British Columbia, Canada. We then examined how functionally related traits underlying energy management – diel variation in cortisol and foraging, social, and movement behaviours — predicted stock-level variation in growth during the freshwater life history stage, which is a performance metric under aquaculture selection. Outbreeding generated significant variation in diel cortisol secretion and behaviours across stocks, and these traits co-varied, suggesting tight integration despite hybridization. The coupling of nighttime cortisol exposure with the daytime behavioural phenotype was the strongest predictor of stock-level variation in body mass. Our results suggest that selection for an integrated phenotype rather than on a single mechanistic trait alone can generate the greatest effect on aquaculture fish growth under outbreeding practices. Furthermore, selecting for these traits at the stock level may increase efficiency of farming methods designed to consistently maximize fish performance on a large scale.

scholarly journals Evaluation of Long-Term Mark-Recapture Data for Estimating Abundance of Juvenile Fall-Run Chinook Salmon on the Stanislaus River from 1996 to 2017

2019 ◽  
Vol 17 (1) ◽  
Author(s):  
Tyler Pilger ◽  
Matthew Peterson ◽  
Dana Lee ◽  
Andrea Fuller ◽  
Doug Demko
Keyword(s):  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Estimation Method ◽  
Central Valley ◽  
Mark Recapture ◽  
Important Species ◽  
Trap Efficiency ◽  
Monitoring Programs ◽  
Abundance Estimates

Conservation and management of culturally and economically important species rely on monitoring programs to provide accurate and robust estimates of population size. Rotary screw traps (RSTs) are often used to monitor populations of anadromous fish, including fall-run Chinook Salmon (Oncorhynchus tshawytscha) in California’s Central Valley. Abundance estimates from RST data depend on estimating a trap's efficiency via mark-recapture releases. Because efficiency estimates are highly variable and influenced by many factors, abundance estimates can be highly uncertain. An additional complication is the multiple accepted methods for how to apply a limited number of trap efficiency estimates, each from discrete time-periods, to a population’s downstream migration, which can span months. Yet, few studies have evaluated these different methods, particularly with long-term monitoring programs. We used 21 years of mark-recapture data and RST catch of juvenile fall-run Chinook Salmon on the Stanislaus River, California, to investigate factors associated with trap efficiency variability across years and mark-recapture releases. We compared annual abundance estimates across five methods that differed in treatment of trap efficiency (stratified versus modeled) and statistical approach (frequentist versus Bayesian) to assess the variability of estimates across methods, and to evaluate whether method affected trends in estimated abundance. Consistent with short-term studies, we observed negative associations between estimated trap efficiency and river discharge as well as fish size. Abundance estimates were robust across all methods, frequently having overlapping confidence intervals. Abundance trends, for the number of increases and decreases from year to year, did not differ across methods. Estimated juvenile abundances were significantly related to adult escapement counts, and the relationship did not depend on estimation method. Understanding the sources of uncertainty related to abundance estimates is necessary to ensure that high-quality estimates are used in life cycle and stock-recruitment modeling.

Application of decision analysis to evaluate recovery actions for threatened Snake River spring and summer chinook salmon (Oncorhynchus tshawytscha)

2001 ◽  
Vol 58 (12) ◽  
pp. 2431-2446 ◽  
Author(s):  
Calvin N Peters ◽  
David R Marmorek
Keyword(s):  
Decision Analysis ◽  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Life Stage ◽  
Anthropogenic Factors ◽  
Snake River ◽  
Risk Averse ◽  
Term Survival ◽  
Wide Range

There is uncertainty about the importance of various factors in explaining declines of chinook salmon (Oncorhynchus tshawytscha) populations in the Snake River basin of Oregon and Idaho. This uncertainty has prevented implementation of long-term recovery actions for these stocks. We used simulation models and decision analysis to evaluate three management actions for seven index stocks of Snake River spring and summer chinook salmon: (i) continue current operation of the Columbia River hydropower system, (ii) maximize transportation of smolts, and (iii) natural river drawdown (breaching) of four Snake River dams. Decision analysis provided a useful approach for including multiple hypotheses about population responses to environmental and anthropogenic factors, systematically assessing the importance of alternative hypotheses, and identifying risk-averse recovery strategies that meet survival and recovery goals over a wide range of uncertainties. We found that the most influential uncertainties were related to hypothesized causes of estuary and ocean mortality. Current monitoring provides limited information on survival in this life stage; carefully designed management experiments are more likely to generate useful information. Given that these uncertainties exist, drawdown was the most risk-averse action, meeting long-term survival and recovery goals over a wider range of assumptions than the other actions.

scholarly journals Juvenile Chinook salmon use of sandbar willows in a large-scale, simulated riparian floodplain: microhabitat and energetics

2021 ◽  
Author(s):  
Nann A. Fangue ◽  
Dennis E. Cocherell ◽  
Florian Mauduit ◽  
Jamilynn B. Poletto ◽  
Kara Carr ◽  
...  
Keyword(s):  
Chinook Salmon ◽  
Large Scale ◽  
River Flow ◽  
Oncorhynchus Tshawytscha ◽  
Energetic Costs ◽  
Juvenile Chinook Salmon ◽  
Consumption Rates ◽  
Floodplain Inundation ◽  
Test Velocity ◽  
Juvenile Chinook

AbstractOutmigrating, juvenile Chinook salmon Oncorhynchus tshawytscha, with access to floodplains (e.g., Yolo Bypass California, USA), grow faster than those restricted to the main channel of the Sacramento River. How these young salmon might use rooted, vegetative structure (e.g., to decrease energy expenditures) while holding positions in flowing water on floodplains and flooded riparian zones is unknown. We conducted daytime experiments in a large (24.4 m long) flume containing a planted area (9.76 m × 1.22 m) of sandbar willows, Salix interior. Flume water was maintained at 1.5 m depth and 16 °C over a 15–90 cm s−1 test velocity range. Fish were videoed using 19 cameras to determine positional behavior, including their depth, use of vegetation, and tail-beat (body-undulation) frequencies (TBFs). These TBFs were replicated with similarly-sized salmon in a calibrated, Brett-type swimming respirometer, where oxygen consumption rates were measured. Using these laboratory measurements, we estimated their swimming velocities and energetic costs associated with occupying sandbar willow habitats in the flume. As flume velocities increased and the leafy canopies of the willows were bent over from the flow, salmon occupied deeper water, among the thick stems of the willows, and maintained their positions. Even at the highest (90 cm s−1) nominal flume velocities, their estimated swimming velocities were only 35.6 cm s−1, within the bottom 15 cm of the water column. This resulted in unchanged energetic costs, compared with those estimated at lower nominal water velocities. The use of vegetated (e.g., with sandbar willow common to the riparian zone) floodplains, rather than non-vegetated ones, can potentially provide energy-saving, growth-promoting daytime habitat for migrating juvenile salmonids during river-flow periods that include floodplain inundation.

scholarly journals A comparison of infectious agents between hatchery-enhanced and wild out-migrating juvenile chinook salmon (Oncorhynchus tshawytscha) from Cowichan River, British Columbia

FACETS ◽  
2018 ◽  
Vol 3 (1) ◽  
pp. 695-721 ◽  
Author(s):  
Krishna K. Thakur ◽  
Raphaël Vanderstichel ◽  
Shaorong Li ◽  
Emilie Laurin ◽  
Strahan Tucker ◽  
...  
Keyword(s):  
Pacific Northwest ◽  
Chinook Salmon ◽  
Large Scale ◽  
Oncorhynchus Tshawytscha ◽  
Pacific Salmon ◽  
River System ◽  
Infectious Agents ◽  
Juvenile Chinook Salmon ◽  
Hatchery Fish ◽  
Juvenile Chinook

Infectious diseases are likely contributing to large-scale declines in chinook salmon stocks in the Pacific Northwest, but the specific agents and diseases involved, and the prevalences in migratory salmon, are mostly unknown. We applied a high-throughput microfluidics platform to screen for 45 infectious agents in 556 out-migrating juvenile chinook salmon, collected from freshwater (FW) and saltwater (SW) locations in the Cowichan River system on Vancouver Island, Canada, during 2014. Nineteen agents (5 bacterial, 2 viral, and 12 parasitic) were detected, with prevalences ranging from 0.2% to 57.6%. Co-infections between Candidatus Branchiomonas cysticola Toenshoff, Kvellestad, Mitchell, Steinum, Falk, Colquhoun & Horn, 2012, Paranucleospora theridion Nylund, Nylund, Watanabe, Arnesen & Kalrsbakk, 2010, and gill chlamydia, all associated with gill disease, were observed in SW samples. We detected agents known to cause large-scale mortalities in Pacific salmon ( Ceratonova shasta (Noble, 1950), Parvicapsula minibicornis Kent, Whitaker & Dawe, 1977), and agents only recently reported in Pacific salmon in BC ( Ca. B. cysticola, P. theridion, Facilispora margolisi Jones, Prosperi-Porta & Kim, 2012 and Parvicapsula pseudobranchicola Karlsbakk, Saether, Hostlund, Fjellsoy & Nylund, 2002). Wild and hatchery fish were most divergent in agent profiles in FW, with higher agent diversity in wild fish. Differences in prevalence largely dissipated once they converged in the marine environment, although hatchery fish may be infected by a greater diversity of agents sooner after ocean entry by virtue of their more rapid migration from nearshore to offshore environments.

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