NOAA Coastal Storms Program
Ecological Impacts
Setting the Stage
Pacific salmon have tremendous economic, cultural, recreational, and biological importance in the Pacific Northwest region. For example, they are
- One of the most valuable commercial fisheries in the United States,
- A resource relied upon by native Americans for nutrition, income, and culture,
- A prominent recreational fishery,
- Providers of important nutrients to inland riparian areas, and
- A primary food source for marine mammals, such as killer whales, and many birds and land mammals.
Seven species of Pacific salmon and trout are found in the Pacific Northwest, many of which are considered endangered or threatened under federal and state laws. To learn more about the current status of Pacific salmon, see NOAA’s webpage on Endangered Species Act Salmon Listings or the US Fish and Wildlife Service's page on Bull Trout.
To understand how different processes affect salmon, an appreciation of their complex life cycle is essential.
The Salmon Life Cycle
Pacific salmon have a unique life history or cycle, which requires them to rely on multiple habitat types (streams, rivers, lakes, estuaries, and the ocean). Coho salmon (Oncorhynchus kisutch) are commonly found in the Pacific Northwest and are referred to as silvers. Some species spend a full year in the stream where they were born before migrating out to sea. As adults, they spend about 15 months at sea before returning to the stream where they were born to reproduce (spawn).
Roll over each image below for additional information on that life stage.
A New Generation is Born |
|
The salmonid eggs incubate within their gravel nest (redd). |
Hatchlings |
|
Young salmonids (alevins) hatch from the eggs and remain in the redd until they are ready to feed. |
Young salmon |
|
Juvenile salmonids (fry) rear in freshwater. Depending upon the species, young salmonids may stay from a few months to three years before migrating to sea. |
Smolts |
|
As juveniles mature, they smolt (undergo physiological changes that prepare them to survive in saltwater). The estuarine environment provides an important place for juveniles to feed and grow prior to migrating to the ocean. |
Ocean Life |
|
Adult salmonids live and grow in the ocean for between one and three years depending on the species. At sea, adult salmonids are pelagic - occurring in the open sea - and prey mostly on other fishes. |
Return to Esuary |
|
Estuaries are equally important as an environment for adult salmonids to undergo the physiological changes necessary to prepare them to survive in fresh water prior to migrating upstream to spawn. |
Return to Streams |
|
Adult salmonids return from the ocean one or more years after outmigration, and migrate upstream to their home stream to spawn. |
Spawning |
|
Spawning salmonids create a gravel nest (redd) on the stream bottom. After spawning, adult salmonids die (some steelhead live to spawn again), but the next generation will soon be born. |
Salmon and Restoration
|
|
|
Restored portion of Longfellow Creek showing weirs |
Because salmon utilize multiple habitat types, restoration projects in the Pacific Northwest focus on improving habitat for all life stages of salmon
- Gravel size, stream flow, and temperature are important factors for salmon embryos;
- Young salmon (fry and parr) require invertebrate food sources and shelter;
- Healthy estuaries are necessary for smolt development; and
- Access to streams and suitable spawning habitat are required by spawning adults.
Now that you have some understanding of salmon and their habitat requirements, you are ready to proceed to the Opening Statement and Objectives of the investigation.