Spring Chinook Salmon Interactions Indices - Competition

Purpose

• Historical estimate of 120,000 adult spring Chinook returning to upper Yakima
• What are the factors that limit carrying capacity of juvenile spring Chinook salmon in the upper Yakima River?

Beverton/Holt and Ricker

Importance of Density Dependence

Capacity changes Yakima River at Cle Elum 98-06

Discharge vs. Cross Sectional Area

Food vs. Flow (2006)

Length vs. Focal Velocity 98-06

What happens to habitable area of juvenile Chinook when discharge increases dramatically relative to normal?

Normal vs. Managed Measures Yakima River at Cle Elum 98-06

Habitat area goes down (2005-2006)

% of habitable area (05-06)

Nelson Hydrograph

Increase in habitable area (05-06)

Distribution of SPC (Nelson)

If flow is influencing habitable space, then what is the magnitude of impact to juvenile spring Chinook salmon and the supplementation program?

Assumptions

• Ksp (minimum number of spawners to produce asymptotic number of juvenile progeny) is limited to 750 redds because of artificially high discharge during the summer
• Artificially high discharge limits availability of food and space to juvenile Chinook (below natural levels)
• Normal capacity without artificial discharge is 2,250 redds

Hypothetical Flow Mortality

Until effects of artificial flows and passage are addressed then the scope of supplementation success will be limited by the current capacity

Acknowledgments

• BPA – Patty Smith, David Byrnes
• WDFW – Timothy Webster, Anthony Fritts, Natalia Pitts, Charity Davidson, Molly Kelly
• YN – Mark Johnston, Bill Bosch, and Chandler/Redd crews
• Cascade Aquatics – Paul James and field staff

Cle Elum

Nelson

Discharge vs. Habitable Area

Cle Elum cross-sectional area

Nelson

Genetic and Environ. Capacity