What is Variability ? Change with location or through time in the capacity of a freshwater system to support salmon Spatial Variation –Natural variability in conditions –Variable intensity of human impacts –Interaction between watershed condition and human effects Temporal Variation –Interannual variation in weather –Catastrophic disturbance –Cyclical or unidirectional changes in climate Spatial-Temporal segregation is artificial - temporal changes in condition are a major factor in creating spatial variation

Variability in Annual Coho Production Bisson and Bilby 1998 Juvenile Coho Production (g/m 2 /y)

Factors Associated with Coho Salmon Abundance Snohomish Basin Pess et al. 2002

Temporal Variation Year-to-year variation in flow, temperature etc. Life history specific effects Examples Winter floods - decreased egg-fry survival Spring high flows - increase fry emigration Summer drought - decreased summer fry survival and growth Autumn high flow - enhanced access to spawning habitat Long-term variations Recovery from disturbance Climatic changes (PDO, global warming)

Winter Flow and Population Performance Unpublished data, Beamer and Pess (with apologies)

Productivity A B C D E F low high Time Since Disturbance (yrs) Temporal Changes in Salmonid Production

Temporal Changes in Salmonid Diversity Diversity low high Time Since Disturbance (yrs) A G H I

Juvenile Coho Production (mg/m 2 /d) Bisson et al Coho Salmon Productivity after the Eruption of Mt. St. Helens Year

Disturbed Site Buffered Site Density (fish/m 2 )

5 Years after Disturbance 60 Years after Disturbance Thrash Creek Biomass = 3.00 g/m 2 Beaver Creek Biomass = 3.28 g/m 2 Hicks et al. 1991

Year 0 Year 50 Patterns in Stream Productivity Low Medium High

Questions 1) How can variability be incorporated into predictions of salmon capacity, growth and productivity? 2) What are the largest sources of uncertainty in predicting salmon response to freshwater habitat conditions? 3) What alternative scenarios of current and future conditions should the model strive to explore? 4) At what spatial scale should wood abundance be characterized to be most meaningful to salmon? 5) What habitat is most important; freshwater, estuarine or marine? 6) What nutrient contribution from salmon carcasses is required to achieve maximum smolt production? How can this aspect of habitat be incorporated into the model?

Q 1&2: Incorporating Variability Spatially explicit predictions - recognize that not all places are equal and a few locations can support the majority of all freshwater production Most influential life history stage varies interannually; build in hydrological fluctuations (flood, drought) and adjust the survival of the affected life history stage accordingly Major disturbance events cause predictable patterns of change in productivity Recognize that the performance of the fish at one stage influences survival later in life; higher spring-summer growth rates increase overwinter survival; larger smolt size increases marine survival Failure to include factors other than physical habitat in relationships to salmon production a major source of uncertainty in current modeling approaches

What is Salmon Habitat? Combination of physical, chemical and biological attributes Physical –Access –Sediment levels, channel morphology Chemical –Water temperature –Contaminants –Nutrient availability Biological –Primary and secondary production –Competition and predation.

Q 3: Habitat Scenarios High Quality Salmon Habitat –Low Elevation –Low Gradient Channels –Diversity of Riparian and Channel Conditions –Low-level of Human Influence People and Salmon Occupy Similar Habitats

Urbanization Effects on Fish Communities Urbanization (% Impervious Area) % Coho % of fish community composed of coho salmon with increasing levels of urbanization for 11 watersheds in King County, Washington. From Lucchetti and Furstenberg 1993.

Population in King, Pierce and Snohomish Counties

Alternative Growth Scenarios Future development will disproportionately impact sites with high productive potential Evaluate effect of different patterns of development –Concentrate new growth in already populated areas –Unrestricted development focused on low relief, low elevation locations –Current zoning plans

Q 4: Appropriate Scale for Wood Wood-fish relationships are tenuous Relates to failure to consider other aspects of habitat Best relationships with winter abundance of coho salmon Ideally, wood abundance and distribution at the watershed scale Response to wood in a reach with a mix of conditions typically associated with high production will be greater than in a reach with poorer underlying condition for the fish

Q 5: Which Habitat is Most Important Answer - All Relative importance vary with conditions –Poor freshwater habitat and extreme weather conditions sufficient mortality may occur prior to smolting to preclude adjustments later –More benign freshwater conditions and enough smolts may be produced to exceed estuarine capacity –Recent experience on the Columbia indicates the significance of early marine rearing condition All habitats are connected Freshwater conditions can influence smolt size and number - affects survival in the estuary and ocean Estuarine conditions can also effect size and number of fish entering the ocean Ocean conditions dictate adult growth and survival, influences the number of fish returning and delivering nutrients to freshwater - influences freshwater habitat condition

Average Weight (g) salmon carcasses present Bilby et al Q 6: Nutrient Contribution from Spawning Salmon

Snoqualmie Deschutes Chehalis Hoh Hoko Willapa Skagit Bogachiel Soleduck Dickey Skykomish Clallam Sample Locations

Index of 15 N Enrichment Carcass Availability (kg/m 2 ) Bilby et al. 2001

Approximate 15 N Saturation Level Bilby et al. 2001