Bayesian decision analysis for status of Snake River spring?summer Chinook salmon Oncorhynchus tshawytscha populations at extinction risk

2007 ◽  
Vol 73 (4) ◽  
pp. 808-816 ◽  
Author(s):  
Saang-Yoon HYUN ◽  
Rishi SHARMA
Keyword(s):  
Decision Analysis ◽  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Extinction Risk ◽  
Snake River ◽  
Bayesian Decision

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.

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

2001 ◽  
Vol 58 (12) ◽  
pp. 2447-2458 ◽  
Author(s):  
Calvin N Peters ◽  
David R Marmorek ◽  
Richard B Deriso
Keyword(s):  
Decision Analysis ◽  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Survival Rates ◽  
Research Priorities ◽  
Snake River ◽  
Posterior Distributions ◽  
Analysis Framework ◽  
Alternative Hypotheses

We used models and decision analysis to incorporate uncertainties into evaluations of two recovery actions for Snake River fall chinook salmon (Oncorhynchus tshawytscha): (i) maximize transportation and (ii) natural river drawdown of four lower Snake River dams. In the retrospective analysis, we compared alternative stock–recruit models and selected one that was consistent with historical spawner–recruit data and allowed us to implement alternative hypotheses about hydrosystem, hatchery, harvest, and environmental effects. In the prospective analysis, we used this model and posterior distributions of its parameters in a decision analysis framework to compare projected escapements for the two actions over a range of alternative hypotheses. We found that drawdown was most risk averse, producing larger long-term escapements than maximizing transportation under most hypotheses and model assumptions. Maximizing transportation and drawdown produced similar escapements only if we assumed high or increasing estuary and ocean survival rates of transported fish coupled with either severe reductions in harvest rates or insensitivity of upstream survival rates to dam construction and removal. Although there was relatively little information available for Snake River fall chinook (particularly about estuary and ocean survival rates of transported smolts), decision analysis was a useful technique for organizing data, assessing actions over a range of uncertainties, and identifying research priorities.

A multiple-reach model describing the migratory behavior of Snake River yearling chinook salmon (Oncorhynchus tshawytscha)

1998 ◽  
Vol 55 (3) ◽  
pp. 658-667 ◽  
Author(s):  
Richard W Zabel ◽  
James J Anderson ◽  
Pamela A Shaw
Keyword(s):  
Chinook Salmon ◽  
Migration Rate ◽  
River Flow ◽  
Oncorhynchus Tshawytscha ◽  
Nonlinear Models ◽  
Columbia River ◽  
River System ◽  
Snake River ◽  
Migration Route ◽  
Time Step

A multiple-reach model was developed to describe the downstream migration of juvenile salmonids in the Columbia River system. Migration rate for cohorts of fish was allowed to vary by reach and time step. A nested sequence of linear and nonlinear models related the variation in migration rates to river flow, date in season, and experience in the river. By comparing predicted with observed travel times at multiple observation sites along the migration route, the relative performance of the migration rate models was assessed. The analysis was applied to cohorts of yearling chinook salmon (Oncorhynchus tshawytscha) captured at the Snake River Trap near Lewiston, Idaho, and fitted with passive integrated transponder (PIT) tags over the 8-year period 1989-1996. The fish were observed at Lower Granite and Little Goose dams on the Snake River and McNary Dam on the Columbia River covering a migration distance of 277 km. The data supported a model containing two behavioral components: a flow term related to season where fish spend more time in regions of higher river velocity later in the season and a flow-independent experience effect where the fish migrate faster the longer they have been in the river.

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.

Sign in / Sign up

Export Citation Format

Share Document