Presentation Abstract
We assessed futures of the Cowichan River’s anadromous Chinook and Coho salmon populations using a proposed methodology for Cumulative Effects Assessment. First, we examined linkages between salmon survival and effect drivers; we built quantitative models to predict changes in salmon survival in response to changes in effect drivers; created scenarios of divergent futures for each effect driver; and, by applying the models, projected salmon survival for each scenario. We conducted assessment for both early freshwater and marine environments. In fresh water, we focused on two main factors: streamflow and stream temperature, and two main drivers: land use and climate change. In the marine environment, we used Pearson correlation and stepwise regression analysis to establish linkages between salmon (Cowichan River Chinook, Strait of Georgia hatchery-raised Coho and wild Coho) survival and environmental factors during the first year of marine residence. Predictive models were developed based on regression analysis that explained at least 70% of variability in Chinook freshwater survival and marine survival of all three populations based on a subset of environmental factors. The models were applied to project future salmon survival in 2050 under four scenarios created by combining two opposite scenarios of land use: conservation and development, and two climate change scenarios, more extreme and moderate. Scenario projections showed a decrease in overall survival by 2050 for all three salmon populations. None of them are likely to survive in extreme climate change scenarios, while moderate climate change scenarios showed positive survival rates although lower than present-day levels. Land use management in the watershed also influenced both Chinook and Coho freshwater survival and Chinook marine survival through effects of river discharge on nearshore processes. However, our land-use management scenarios have considerably weaker effect on salmon survival than climate change.
Session Title
Hatchery, Habitat, & Survival
Conference Track
SSE4: Fish Science and Policy
Conference Name
Salish Sea Ecosystem Conference (2022 : Online)
Document Type
Event
SSEC Identifier
SSE-traditionals-243
Start Date
27-4-2022 1:30 PM
End Date
27-4-2022 3:00 PM
Rights
Copying of this document in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this document for commercial purposes, or for financial gain, shall not be allowed without the author's written permission.
Type
Text
Language
English
Assessing Futures of Two Cowichan River Pacific Salmon Species, Chinook and Coho, Using Scenario Analysis for Cumulative Effects Assessment
We assessed futures of the Cowichan River’s anadromous Chinook and Coho salmon populations using a proposed methodology for Cumulative Effects Assessment. First, we examined linkages between salmon survival and effect drivers; we built quantitative models to predict changes in salmon survival in response to changes in effect drivers; created scenarios of divergent futures for each effect driver; and, by applying the models, projected salmon survival for each scenario. We conducted assessment for both early freshwater and marine environments. In fresh water, we focused on two main factors: streamflow and stream temperature, and two main drivers: land use and climate change. In the marine environment, we used Pearson correlation and stepwise regression analysis to establish linkages between salmon (Cowichan River Chinook, Strait of Georgia hatchery-raised Coho and wild Coho) survival and environmental factors during the first year of marine residence. Predictive models were developed based on regression analysis that explained at least 70% of variability in Chinook freshwater survival and marine survival of all three populations based on a subset of environmental factors. The models were applied to project future salmon survival in 2050 under four scenarios created by combining two opposite scenarios of land use: conservation and development, and two climate change scenarios, more extreme and moderate. Scenario projections showed a decrease in overall survival by 2050 for all three salmon populations. None of them are likely to survive in extreme climate change scenarios, while moderate climate change scenarios showed positive survival rates although lower than present-day levels. Land use management in the watershed also influenced both Chinook and Coho freshwater survival and Chinook marine survival through effects of river discharge on nearshore processes. However, our land-use management scenarios have considerably weaker effect on salmon survival than climate change.
