Ecosystem Interactions and Pacific Salmon

Pacific salmon are keystone species, and play an essential role in the health and function of ecosystems. Salmon benefit other species as food and their bodies enrich habitats through the cycling of nutrients from the ocean to freshwater streams.

West Coast

Salmon swimming in the ocean — Ocean Swimming Salmon. Credit: Shutterstock

Pacific salmon fisheries provide tribal, commercial, and recreational harvest in ocean and inland waters of the West Coast. Salmon are not only important to humans–they are also interconnected with other animals, such as Southern Resident killer whales. When planning salmon fisheries, co-managers consider the conservation needs of the salmon species, their relationships with other organisms, and the larger ecosystem connections with salmon.

Salmon fisheries and management must adapt to shifts in the amount and distribution of fish, and must consider changes to the environment that impact salmon survival when creating management plans. Modifications to coastal and inland habitats have altered the essential spawning, rearing, and migration environments and connections for salmon between freshwater and the ocean environments. This results in the need for habitat protection and restoration. Salmon and steelhead can also be vulnerable to climate change because they need cold water to spawn and grow in their aquatic environments.

Southern Resident Killer Whales and Amendment 21

Killer whales at sea — Southern Resident killer whales. Credit: NOAA Fisheries

Pacific salmon and the management of Pacific salmon fisheries can also affect Southern Resident killer whales. Listed under the Endangered Species Act (ESA), Southern Resident killer whales mainly consume Chinook salmon. If the whales have difficulty in finding enough prey, this could result in a decline in their health, reproduction, and survival.

To increase availability of Chinook salmon as food for Southern Resident killer whales, NOAA Fisheries approved an amendment (Amendment 21) to the Pacific Fishery Management Council’s Salmon Fishery Management Plan in September 2021. Amendment 21 improves Chinook availability as prey for Southern Resident killer whales from ocean fisheries by limiting commercial and recreational fishing off the West Coast of the United States when Chinook salmon abundance is too low. The amendment is an example of managing salmon fisheries while considering species interactions and predator-prey relationships. The best available science about Southern Resident killer whales and their prey, Chinook salmon, was considered in the development of Amendment 21.

The following actions and locations are included in Amendment 21 and would be implemented if Chinook salmon numbers fall below a specified level of low abundance:

Reduce fishing quotas north of Cape Falcon, Oregon
Close areas off the Columbia River and Grays Harbor, to all but tribal treaty fishing, until June 15
Delay the ocean commercial troll fishery between Cape Falcon and the California/Oregon border until April 1
Close areas off the Klamath River and Monterey Bay in California to recreational and commercial Chinook salmon fishing from October 1 to March 31

Learn more about Southern Resident Killer Whales

Habitat Restoration and Why It Matters

Habitat loss, both in quantity and quality, has been identified as one of the greatest risks to survival for Pacific salmon and steelhead populations. The restoration of habitat is essential for the recovery of salmon and steelhead populations across the West Coast.

Habitat restoration is one approach used to rebuild damaged habitat and to protect a functioning environment. Habitat restoration is completed in a variety of locations including coastal wetlands, streams, and shoreline habitats which are valuable to juvenile salmon. NOAA Fisheries is committed to the restoration and protection of habitat for salmon species. Benefits to salmon from habitat restoration include providing ecosystems and habitats which help improve nutrient flow and freshwater productivity. Additional benefits from habitat restoration consist of support as important nursery areas to rear, and as migration corridors to help salmon on their way to the ocean. Healthy habitat is critical for sustaining healthy salmon populations and the tribal, commercial, and recreational fisheries which rely on them.

NOAA Fisheries supports salmon habitat restoration projects through the NOAA Restoration Center and Pacific Coastal Salmon Recovery Fund. The Center and Fund work towards the restoration of nearshore habitats and estuaries which are essential to salmon. Restoration projects these organizations take on include the removal of levees and shoreline armoring, and the restoration of tidal channels.

The Community-based Restoration Program is one example where NOAA Fisheries and other partners have helped create and meet habitat restoration goals in estuary areas. Areas in the Restoration Program include Fisher Slough, Wiley Slough, and Fir Island Farm along the Skagit River. The Skagit River estuary provides important habitat for Chinook salmon. Much habitat restoration work has been completed in the Skagit River estuary which contributes to Chinook salmon recovery, yet continued effort is necessary to achieve population recovery goals.

Learn more about NOAA’s involvement in habitat restoration:

Nearshore Habitats and Salmon Survival

Nearshore habitats are extremely important to the Pacific salmon and steelhead life cycle. Juvenile salmon use nearshore habitats when they are young as a safe space to grow and hide from predators. Examples of nearshore environments include beaches, bluffs, inlets, river deltas, and estuaries.

Estuaries are locations where salt water from the ocean meets and mixes with freshwater from streams at the mouth of rivers. Estuaries provide a place for juveniles to feed, hide from predators, and to prepare for traveling into the ocean for the next stage of their life.

Nearshore areas are also important for Chinook salmon, as they move into the ocean. The abundance of salmon can impact other species in nearshore ecosystems, but the condition of these ecosystems can also impact the number of salmon. The time, nourishment, and growth salmon experience in nearshore environments helps them increase their chances of survival in the ocean.

In the past, human expansion into large areas of nearshore and estuary habitats have degraded or destroyed many of these critical nursery areas for salmon, such as in Puget Sound and the San Francisco Bay. The damage to and loss of nearshore habitat has affected salmon at a vital point in their life cycle and continue to remain major obstacles to their recovery.

NOAA Fisheries has focused resources on protection and restoration of nearshore habitat. Learn more about salmon and habitats through the following resources:

Supporting Salmon Recovery in Puget Sound

Lake Washington / Lake Sammamish Basin Warm Water Fisheries

Map of Lake Washington — General Map of the Lake Washington Region

Predation from invasive fish species is a threat to salmon and steelhead populations. One action to address this threat is being undertaken by the Muckleshoot Tribe in the Lake Washington basin in Puget Sound. In 2017, the Muckleshoot Indian Tribe (MIT) and the Washington Department of Fish and Wildlife (WDFW) began an assessment of the fish populations in the basin. The MIT designed a test fishery to study the Lake Washington ecosystem and remove non-native fish that prey on native juvenile salmon and steelhead, while avoiding impacts to ESA-listed species. Historically, many local tribes (Duwamish, Muckleshoot, and Suquamish) used the greater Seattle area and Lake Washington basin for fishing and shellfish harvest. However, large scale landscape modifications in the early 1900s caused extensive changes to the natural resources and impacts to the residents in the area. The decrease in available fish passage reduced the native Chinook salmon and steelhead populations, which led to their listing under the Endangered Species Act (ESA). These populations have continued to decline, particularly within the past decade, but efforts initiated by the Muckleshoot Indian Tribe contribute to invasive species removal, and salmon and steelhead recovery in Lake Washington. The MIT test fishery catch is annually reported to NOAA Fisheries. The identification of species in the test fishery will continue to inform MIT and WDFW on how to best support the recovery of native salmon and steelhead in the basin.

Learn more about the Muckleshoot Indian Tribe

Climate Change Impacts on Salmon and Steelhead

Tagged Steelhead. Credit: John McMillan/NOAA

A large-scale version of habitat degradation is the impact of climate change. NOAA Fisheries studies and evaluates the susceptibility of Pacific salmon and steelhead to changing climate and ocean conditions, and how these changes will affect different populations of Pacific salmon and steelhead. NOAA Fisheries also examines how changes in climate affect salmon habitat, and salmon and steelhead life cycles.

The warming climate is affecting temperatures and conditions of the ocean, rivers, and streams that salmon and steelhead rely on for survival. The changing conditions may affect salmon and steelhead in varying ways throughout their life cycle and in different habitats:

Climate change can affect the availability of cold-water habitat necessary for salmon when in freshwater habitats.
Alterations in stream temperature and/or flow may modify fish development, growth, timing of migration, and survival.
Less water available from rain and melted snow, may lead to salmon struggling to travel the great distances between their spawning grounds and the ocean.

NOAA Fisheries’ Northwest Fisheries Science Center used life-cycle models to predict climate effects on Chinook salmon throughout their life stages by studying one distinct Chinook salmon population. For example, the projections from the model predict that Snake River spring/summer Chinook salmon populations could decline over the next several years from climate change impacts. This may be due to an increase in ocean temperature, and variations in flow and temperatures in freshwater systems. Recent heat events, which caused changes in salmon populations, may indicate what could happen as the ocean becomes warmer. A marine heatwave from 2014 to 2015 raised ocean temperatures, and salmon returns decreased coastwide.

School of adult chinook salmon — Spring Chinook Salmon. Credit: Michael Humling, U.S. Fish & Wildlife Service

The results from such modeling may help inform conservation work and improve the survivability of salmon and steelhead in the Columbia River Basin. Restoration of habitats in the basin could enhance survival of juvenile fish before their move to the ocean and buffer impacts from climate change. This can occur through food and growth opportunities for fish, and by increasing supportive habitat conditions. Protecting habitats may contribute to healthier fish, which could result in salmon having a better chance of survival with the change in climate and increase in ocean temperatures.

A climate vulnerability assessment of Pacific salmon to changing climate and ocean conditions along the U.S. West Coast was conducted by the NOAA Fisheries’ Northwest Fisheries Science Center. The report focused on 33 threatened and endangered Pacific salmon and steelhead distinct populations to better understand climate impacts on the species. The assessment found that Chinook, coho, and sockeye salmon are susceptible to climate-related changes in their environment. Major climate threats stated in the assessment that could impact salmon and steelhead populations include sea level rise, fluctuations in high and low freshwater levels, hotter temperatures in oceans and rivers, changes in snowpack and snowmelt, flooding, and ocean acidification. Other species, such as steelhead, pink, and chum salmon, may be more adaptable to environmental variations because they spend the least amount of time in freshwater during their life stages. As the climate shifts, concern is growing for salmon populations and their lack of access to important, healthy habitats for their life cycle, such as estuaries, rivers, and streams.

The salmon life cycle begins in freshwater streams. Juveniles travel to the ocean, and then return as adults to rivers and their spawning grounds. Salmon face climate challenges in both marine and freshwater environments. The NOAA Fisheries report listed the salmon populations most vulnerable to climate change and least able to adapt as:

Chinook salmon in California’s Central Valley
Coho salmon in California and southern Oregon
Snake River sockeye salmon
Spring-run Chinook salmon in the interior Columbia and Willamette River basins

Climate change will continue to be a problem for species, including salmon and steelhead populations. The report also assessed salmon and steelhead capability to adjust to climate change. Some populations may modify their movement to and from the ocean to escape the summer heat. Habitat restoration projects that create or restore refuge may provide more habitat diversity, giving vulnerable salmon a chance to adapt to the changes in temperatures and tidal flows. Researchers are continuing to identify specific populations which may need more support as temperatures change and the availability or quality of freshwater habitat decreases.