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This presentation will describe how juvenile salmon, with a focus on Chinook, utilize the nearshore environment and why it is important for their survival and growth. It will discuss the varying use of nearshore habitats within and between different salmon species, including their physical, chemical, and biological characteristics. The presentation will also highlight the functions of the nearshore for juvenile salmon, such as feeding, growth, predator avoidance, and physiological transitions. Additionally, it will explore the role of the nearshore in contributing to the resilience and persistence of salmon populations and the importance of conserving nearshore habitats for salmon recovery efforts.
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OBJECTIVES OF PRESENTATION • DESCRIBE HOW JUVENILE SALMON USE THE NEARSHORE (FOCUS WILL BE ON CHINOOK) • DESCRIBE WHY THE NEARSHORE IS IMPORTANT TO JUVENILE SALMON
Most Use Ocean type chinook Chum Pink Coho (fry) Coho (yearlings) Stream type chinook Sockeye Steelhead Least Use Most Use Fry Fingerlings Yearlings Least Use USE OF THE NEARSHORE VARIES BETWEEN AND WITHIN SPECIES
HABITAT: Physical, chemical and biological characteristics of a specific unit of the environment occupied by salmon
Fry Migrants Smolts
Abundance of Fry, Smolts, and Yearlings Entering the Estuary Population- Genetic Makeup Spawning Location FW Habitat Climate Biological- Competition Freshwater Environment Fry Smolts Yearlings
Site Scale Depth Velocity Salinity Temperature Nutrients Substrate- Fine Vegetation- Marsh Landscape Scale Position in Estuary Connectivity Size Shape Salinity Tidal Regime Juvenile Salmon Habitats: Estuary/Delta
Fry Migrants Smolts
Site Scale Depth Velocity Salinity Temperature Nutrients Substrate- Variable Vegetation- Eelgrass Gradient Exposure Landscape Scale Position Along NS Connectivity Size Shape Composition of Adjacent Habitats Inshore--Offshore Juvenile Salmon Habitats: Nearshore Shoreline Areas
Importance of The Nearshore to Juvenile Salmon • Contributes to resilience and persistence of salmon populations. • Helps produce adult fish.
The Nearshore Produces Adults Oregon Coast (Reimers) 1. Fry migrants 2. Subyearling estuarine smolt (brief estuary rearing) 3. Subyearling estuarine smolt (long estuary rearing) 4. Subyearling riverine smolt 5. Yearling riverine smolt Campbell River Estuary (MacDonald et al.) 1. Use of Nearshore Contributes to Adult Returns Skagit River (E. Beamer) 1. Adult spawners produced by fry migrants
Functions of Nearshore for Juvenile Salmon • Feeding and Growth - Multiple sources of food - Much of the production is internally derived - High growth rates 2. Predator avoidance 3. Physiological transition 4. Migratory corridor
Persistence and Resilience • Nearshore Contributes to Diversity of Chinook Salmon Populations • While all Salmon Populations Exhibit Diversity, Chinook Salmon Exhibit an Exceptional Amount • Long Term Population Level Effect that Results From Interaction of Individual Fish With Their Environment
Historic and Contemporary Life Histories One brood year of chinook salmon in the Columbia River estuary Based on data from Rich (1920) & Dawley et al. (1985)
LifeHistoryDiversity Chinook Population Yearlings Fry Migrants Smolts Directly Thru Estuary Extended Rear In Estuary Short FW, Some Estuary Rearing Long PS Phase Short PS Phase
Production Thinking and The Nearshore • What are the “limiting factors” to salmon production? • Is the nearshore a “bottleneck” to salmon production? Is there a carrying capacity? • Are salmon “estuarine dependent”?
Population Thinking • Salmon species are composed of semi-isolated, self-perpetuating groups (populations) • Conservation of a species requires conservation of each component of the population and the habitats that they use • The nearshore is a mixing ground for populations from different spawning and rearing areas upstream • Conservation (protection and restoration) of nearshore habitats is a component of salmon recovery efforts.
Acknowledgements • Randy Shuman, Daniel Smith • King County, Department of Ecology • Steve Schroder • Joe Jauquet • Si Simenstad, H. Shipman, M. Logsdon • Roger Tabor • Dan Bottom