California Current Integrated Ecosystem Assessment

California Current Ecosystem Component: Salmon

Overview

Pacific salmon and steelhead (Oncorhynchus spp.) are iconic members of North Pacific rim ecosystems. They have a dynamic life cycle that includes time in freshwater and marine habitats, and they connect these ecosystems through extensive migrations up to 1500 km.

Historically, salmon supported extensive native harvest along the U.S. West Coast, and in recent times, they have been the focus of large commercial and recreational fisheries. NOAA Fisheries has listed 28 species of salmon and steelhead on the West Coast under the US Endangered Species Act.

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Nested conceptual model of the California Current ecosystem, centered on salmon. The overview illustrates relationships to key environmental drivers; ecological interactions; and human activities.

 

Ecological Interactions

Salmon rely on krill and forage fish to survive the first year. Krill are eaten by salmon but they also indirectly impact salmon through their interaction with forage fish. Conditions conducive to more prey typically lead to more salmon. Larger marine mammals and seabirds prey on salmon.

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Environmental Drivers

Ocean drivers are largely dependent on basin-scale forcing such as PDO state. Specifically, PDO, MEI and such represent the forces that ultimately result in local production. There is also a need to consider regional drivers such as local upwelling and wind dynamics and they translate to water column characteristics and forage dynamics. Freshwater habitat and the factors related to it relate to the production of salmon entering the ocean.

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Human Activities

Pacific salmon support valuable commercial and recreational fisheries across marine, estuarine and freshwater habitats. Conservation measures, including precautionary fisheries management practices and habitat restoration and enhancement efforts, are currently being implemented to sustain and restore salmon populations. Salmon survival, behavior, habitat quality and fishery opportunities may be affected by non-fishing activities related to freshwater diversions, hydropower, land-use practices, and hatchery fish interactions.

Salmon-human connections flowchart

Indicator Status and Trends

Indicators of Pacific salmon abundance focus primarily on escapement (number that escape capture by fisheries) of natural origin Chinook and coho salmon, by major population.

Population condition indicators include population growth rate, proportion of natural-origin spawners, and age structure.