Modeling the Impacts of Climate Change and Restoration on Chinook Salmon in the Snohomish Basin NOAA Matthew WileyJames Battin Elizabeth KorbKrista Bartz Richard PalmerHiroo Imaki Mary Ruckelshaus December 6, 2005

Project Objectives  Examine effects of planned large- scale restoration actions.  Assess how climate change affects Chinook salmon populations  Investigate interactions between climate effects and restoration

Presentation Overview  Climate Change  Experimental Design  Results Climate Impacts Land Use Impacts Chinook Salmon Impacts  Conclusions

Why Forecast Climate Change Impacts? The future ain't what it used to be.

Evidence of Climate Change  Intergovernmental Panel on Climate Change (IPCC) “The Earth’s climate system has demonstrably changed on both global and regional scales since the pre-industrial era, with some of these changes attributable to human activities.” (IPCC2001, Synthesis report, Summary for Policy Makers) “Globally it is very likely that the 1990s were the warmest decade and 1998 the warmest year in the instrumental record ( ).”

Evidence of Climate Change Seasonal trends – by station

Experimental Design 15 land use and climate scenarios

GCM Scenarios  The two scenarios used in this study are from the IPCC’s 2001 Third Assessment Report (TAR)  The Climate Impacts Group has recently started using new high, medium, and low scenarios that will be a part of the Fourth Assessment Report (AR4)  How do the scenarios used in this work compare to the “new” scenarios?

TAR scenarios –GFDL_A2 –HadCM3_A2 AR4 Scenarios –IPSL_A2: high –ECHAM5_A2: medium –GISS_B1: low The GFDL and HadCM3 scenarios, for the 21 st century are between the low and middle AR4 scenarios for temperature Precipitation is highly variable in all scenarios, no significant difference in trends

GFDL and HadCM3 are roughly comparable and middle of the road in terms of temperature. GFDL tends toward ‘wetter’; HadCM3 tends toward ‘drier’. SHIRAz results appear to be more sensitive to the monthly distribution of precipitation than to annual totals. For 2025 and 2050 periods used for analysis…

Experimental Design: Hydrology Model  Driven by meteorology from GCM output and simulate streamflow and temperature  Developed for use in the mountainous watersheds of the Pacific Northwest  150 meter resolution, 3-hour timestep 3 models  Modifications and improvements Groundwater and temperature model DHSVM Layers DHSVM

Experimental Design: Land Use Scenarios

SHIRAZ  Relates changes in environment to changes in salmon population size via: --Capacity --Survival  Life-history-based  Spatially explicit  Stochastic  Stage-structured

Habitat Effects in SHIRAZ Egg-to-juv Survival peak flows temperature Juv. Rearing Capacity stream gradient stream width riparian condition Spawning Capacity stream gradient stream width riparian condition Egg Juvenile Adult Pre-spawning Survival temperature Stochastic Variation in Ocean Survival

Accounting for Uncertainty and Variability  DHSVM: Constructs a series of 72 representative years for a given scenario using the historical pattern of climate variability as a template.  SHIRAZ: Samples from 72-yr DHSVM time series to produce 500 possible 100-year-long population trajectories.

Accounting for Uncertainty and Variability Year Abundance Target Low abundance threshold 0100

What We Are Modeling  Effects of large-scale land use and climate change on stream temperature and flow in the subbasins with least development and most chinook.  Resulting effects on adult and juvenile salmon.

What We Aren’t Modeling  Climate effects on ocean conditions  Climate & restoration effects on sediment  Climate effects on land cover  Behavioral/adaptive response of salmon  Highly urbanized subbasins  Small-scale effects: refugia, riparian planting

Results  Impacts of climate change Meteorology  air temperature and precipitation Hydrology  average, peak, and low flow and stream temperature  Impacts of land use change Hydrology  average, peak, and low flow and temperature  Impacts on Chinook populations

Changes Due to Climate

Climate Impacts- Air Temperature Impacts to average monthly temperature, Snoqualmie Meteorological Station GFDLHadley ° C ° C ° C ° C

Climate Impacts- Precipitation Impacts to average monthly precipitation, Snoqualmie Meteorological Station GFDLHadley

Hydrologic Impacts- Monthly Flow Impacts to average annual streamflow SnoqualmieSkykomish

Hydrologic Impacts- Peak Flow Incubation peak flow-maximum instantaneous flow between Sept. 15th and Feb. 15th GFDL Hadley

Hydrologic Impacts- Low Flow Minimum spawning flow- lowest instantaneous flow between Sept. 15th and Nov. 15th GFDL Hadley

Hydrologic Impacts- Water Temperature Average monthly stream temperature Snoqualmie River Skykomish River Avg. Summer Change ° C Avg. Summer Change ° C Avg. Winter Change ° C Avg. Winter Change ° C

Hydrologic Impacts- Water Temperature Pre-spawning temperature- mean of daily maximum temperatures for July 15th – Oct. 15th GFDL Hadley

Changes Due to Land Use

Hydrologic Impacts- Peak Flow Incubation peak flow-maximum instantaneous flow between Sept. 15th and Feb. 15th Current Path Restoration GFDL Hadley

Hydrologic Impacts- Low Flow Minimum spawning flow- lowest instantaneous flow between Sept. 15th and Nov. 15th Current Path Restoration GFDL Hadley

Hydrologic Impacts- Water Temperature Pre-spawning temperature- mean of daily maximum temperatures between Jul. 15th and Oct. 15th Current Path Restoration GFDL Hadley

Impacts on Chinook Populations

Chinook Population Impacts- Summary SHIRAz scenarios are evaluated three ways 1. mean spawner population size across the Snohomish River basin 2. percent of runs falling below 2,800 spawner threshold set in harvest management plan 3. spatial distribution of spawners by subbasin

Chinook Population Impacts-GFDL Mean population of wild spawners and percent falling below the threshold in GFDL Model

Chinook Population Impacts-Hadley Mean population of wild spawners and percent falling below the threshold in Hadley Model

Chinook Population Impacts-2025 Spatial distribution of changes to mean wild spawners due to 2025 climate AND land Use Current Path Restoration GFDL Hadley

Chinook Population Impacts-2050 Spatial distribution of changes to mean wild spawners due to 2050 climate AND land use Current Path Restoration GFDL Hadley

Conclusions  Climate Impacts Temperatures expected to rise in all months Shift in annual precipitation,  GFDL- more in winter less in summer  Hadley- less in most months  Hydrologic Timing shift, increasing winter peaks and less pronounced spring peaks Earlier spring runoff Reduction in summer streamflow volumes

Conclusions  Salmon Impacts 15-39% reduction in average Chinook numbers in the absence of restoration. 5-23% reduction in average Chinook numbers with restoration. Climate change is likely to decrease our ability to reach salmon population targets.

Chinook Population Impacts- GFDL Upland versus lowland basin effects Wild versus hatchery fish effects Intro > Climate Change > Experimental Design > Results > Climate > Land Use > Chinook Populations > Conclusions