Productivity and survival rate trends in the freshwater spawning and rearing stage of Snake River chinook salmon (Oncorhynchus tshawytscha)

2001 ◽  
Vol 58 (6) ◽  
pp. 1196-1207 ◽  
Author(s):  
C E Petrosky ◽  
H A Schaller ◽  
P Budy
Keyword(s):  
Survival Rate ◽  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Adult Stage ◽  
Life Stage ◽  
Snake River ◽  
Climate Conditions ◽  
Management Actions ◽  
Significant Survival ◽  
Stream Type

Stream-type chinook salmon (Oncorhynchus tshawytscha) populations in the Snake River (northwest United States) have declined dramatically since completion of the federal hydrosystem. Identifying the life stage that is limiting the survival of these stocks is crucial for evaluating the potential of management actions to recover these stocks. We tested the hypothesis that a decrease in productivity and survival rate in the freshwater spawning and rearing (FSR) life stage since completion of the hydropower system could explain the decline observed over the life cycle. The decline of chinook populations following completion of the hydrosystem was not accompanied by major survival changes in the FSR life stage. FSR productivity showed no significant decline, and the FSR survival rate decline was small relative to the overall decline. However, significant survival declines did occur in the smolt-to-adult stage coincident primarily with hydrosystem completion, combined with poorer climate conditions and possibly hatchery effects. Potential improvements in survival that occur only at the FSR life stage are unlikely to offset these impacts and increase survival to a level that ensures the recovery of Snake River stream-type chinook.

Population viability of the Snake River chinook salmon (Oncorhynchus tshawytscha)

1995 ◽  
Vol 52 (7) ◽  
pp. 1442-1448 ◽  
Author(s):  
John M. Emlen
Keyword(s):  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Population Viability ◽  
Snake River ◽  
Management Actions ◽  
Population Dynamics Model ◽  
The Status ◽  
Salmon Population ◽  
Mortality Improvement ◽  
Best Fit

In the presence of historical data, population viability models of intermediate complexity can be parameterized and utilized to project the consequences of various management actions for endangered species. A general stochastic population dynamics model with density feedback, age structure, and autocorrelated environmental fluctuations was constructed and parameterized for best fit over 36 years of spring chinook salmon (Oncorhynchus tshawytscha) redd count data in five Idaho index streams. Simulations indicate that persistence of the Snake River spring chinook salmon population depends primarily on density-independent mortality. Improvement of rearing habitat, predator control, reduced fishing pressure, and improved dam passage all would alleviate density-independent mortality. The current value of the Ricker α should provide for a continuation of the status quo. A recovery of the population to 1957–1961 levels within 100 years would require an approximately 75% increase in survival and (or) fecundity. Manipulations of the Ricker β are likely to have little or no effect on persistence versus extinction, but considerable influence on population size.

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.

Evaluating river management during seaward migration to recover Columbia River stream-type Chinook salmon considering the variation in marine conditions

2014 ◽  
Vol 71 (2) ◽  
pp. 259-271 ◽  
Author(s):  
Howard A. Schaller ◽  
Charles E. Petrosky ◽  
Eric S. Tinus
Keyword(s):  
Marine Environment ◽  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Columbia River ◽  
Temporal Analysis ◽  
Adult Survival ◽  
Snake River ◽  
Data Sets ◽  
Delayed Mortality ◽  
Stream Type

Evidence suggests Snake River stream-type Chinook salmon (Oncorhynchus tshawytscha) experience substantial delayed mortality in the marine environment as a result of their outmigration experience through the Federal Columbia River Power System (FCRPS). We analyzed mortality patterns using methods that incorporated downriver reference populations passing fewer dams, and temporal approaches that were independent of reference populations. Our results from the alternative spatial and temporal methods consistently corroborated with spawner–recruit residuals and smolt-to-adult survival rate data sets, indicating that Snake River salmon survived about one quarter as well as the reference populations. Temporal analysis indicated that a high percentage (76%) of Snake River juvenile salmon that survived the FCRPS subsequently died in the marine environment as a result of their outmigration experience. Through this and previous studies, it is evident that delayed hydrosystem mortality increases with the number of powerhouse passages and decreases with the speed of outmigration. Therefore, a promising conservation approach would be to explore management experiments that evaluate these relationships by increasing managed spill levels at the dams during the spring migration period.

Effect of growth on early sexual maturation in stream-type chinook salmon (Oncorhynchus tshawytscha)

Aquaculture ◽  
1994 ◽  
Vol 121 (1-3) ◽  
pp. 95-103 ◽  
Author(s):  
W.Craig Clarke ◽  
John Blackburn
Keyword(s):  
Sexual Maturation ◽  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Stream Type

Individual variation in dispersal behaviour of newly emerged chinook salmon (Oncorhynchus tshawytscha) from the Upper Fraser River, British Columbia

1997 ◽  
Vol 54 (7) ◽  
pp. 1585-1592 ◽  
Author(s):  
M J Bradford ◽  
G C Taylor
Keyword(s):  
British Columbia ◽  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Population Variation ◽  
Fraser River ◽  
Movement Behaviour ◽  
Spawning Areas ◽  
Dispersal Distances ◽  
Stream Type ◽  
Downstream Movement

Immediately after emergence from spawning gravels, fry of stream-type chinook salmon (Oncorhynchus tshawytscha) populations from tributaries of the upper Fraser River, British Columbia, distribute themselves downstream from the spawning areas, throughout the natal stream, and into the Fraser River. We tested the hypothesis that this range in dispersal distances is caused by innate differences in nocturnal migratory tendency among individuals. Using an experimental stream channel, we found repeatable differences in downstream movement behaviour among newly emerged chinook fry. Fish that moved downstream were larger than those that held position in the channel. However, the incidence of downstream movement behaviours decreased over the first 2 weeks after emergence. We propose that the variation among individuals in downstream movement behaviour we observed leads to the dispersal of newly emerged fry throughout all available rearing habitats. Thus, between- and within-population variation in the freshwater life history observed in these populations may be caused by small differences in the behaviour of individuals.

The importance of influence diagnostics: examples from Snake River chinook salmon spawner-recruit models

2001 ◽  
Vol 58 (3) ◽  
pp. 551-559
Author(s):  
Richard A Hinrichsen
Keyword(s):  
Chinook Salmon ◽  
Main Stem ◽  
Columbia River Basin ◽  
Snake River ◽  
Rapid Decline ◽  
Single Observation ◽  
Influence Diagnostics ◽  
Direct Measurements ◽  
Transportation Program ◽  
Stream Type

The rapid decline of some salmonid populations in the Columbia River Basin led investigators to analyze spawner-recruit (SR) data in order to understand the potential gains of improving main-stem passage conditions and quantify the effectiveness of the juvenile transportation program. Direct measurements of passage survival and transportation were not always available, so instead, the researchers attempted to tease out the passage or transportation effects by using trends in production estimated from SR models. Small subsets of data, or even single observations, highly influenced the estimates of passage survival and transportation effectiveness derived from these models. For stream-type chinook salmon, deleting 1 of 13 stocks changed the estimate of main-stem passage survival from 11 to 34%. For ocean-type chinook salmon, the conclusion that transportation should be immediately halted hinged on a single observation. The Snake River salmon SR models starkly illustrate the importance of using influence diagnostics to temper inferences.

Forecasting climate-induced changes in the survival of Snake River spring/summer Chinook salmon (Oncorhynchus tshawytscha)

2005 ◽  
Vol 14 (6) ◽  
pp. 448-457 ◽  
Author(s):  
MARK D. SCHEUERELL ◽  
JOHN G. WILLIAMS
Keyword(s):  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Snake River ◽  
Induced Changes

Experimental management for Snake River spring–summer chinook (Oncorhynchus tshawytscha): trade-offs between conservation and learning for a threatened species

2002 ◽  
Vol 59 (4) ◽  
pp. 717-725 ◽  
Author(s):  
Charles M Paulsen ◽  
Richard A Hinrichsen
Keyword(s):  
Oncorhynchus Tshawytscha ◽  
Management Strategies ◽  
Snake River ◽  
Evolutionarily Significant Unit ◽  
Management Actions ◽  
Trade Offs ◽  
Increase Productivity ◽  
Population Viability Analyses ◽  
Experimental Management ◽  
Power Analyses

Using Snake River spring–summer chinook (Oncorhynchus tshawytscha) as an example, we explore trade-offs between conservation (restoring population abundance to self-sustaining levels) and learning (reliably estimating how management strategies affect productivity). The population has been studied extensively, especially since 1992, when the evolutionarily significant unit (ESU) was listed under the U.S. Endangered Species Act. Understanding both the conservation and learning dimensions is crucial in evaluating management actions. Using a Bayesian simulation model calibrated with 40+ years of spawner–recruit estimates, we performed population viability analyses to examine the biological risks of an array of management strategies. We also performed power analyses to estimate the precision of estimates of the actions' effects. The results suggest that if one can take actions that increase productivity and manage those actions as experiments, one can simultaneously increase fish numbers and reduce the uncertainty about the effects of those actions. However, because more powerful experiments will utilize controls where no action is taken, an experimental approach may increase risks to the ESU when compared to a strategy that tries to maximize productivity as soon as possible.

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