The search for why large numbers of spawning coho salmon have been dying in Puget Sound's urban streams goes as far back as the 1980s and culminated this year with the discovery of a previously unidentified chemical related to automobile tires. We offer a detailed timeline for the discovery. 

Environmental engineers and chemists at the University of Washington Tacoma have identified a mysterious compound implicated in the deaths of large numbers of coho salmon in Puget Sound. The chemical is linked with a rubber additive commonly used in tires and is thought to kill more than half of the spawning coho that enter the region's urban streams every year. 

Modern automobile tires are a complex mixture of chemicals, all used together in different ways to give tires their structure and properties, including riding comfort, safety and long life. Chemicals from tire wear particles are now thought to be responsible for the deaths of large numbers of coho salmon returning to spawn in Puget Sound streams. 

After a relatively warm summer and fall, and La Niña forming in the tropics, stream flows in the Puget Sound region are now relatively normal. Summer in Puget Sound produced lots of algal and organic material in the water and on beaches, which by October have disappeared. Kelp beds look strong in northern Puget Sound and the Straits; and the harvest of the annual chum salmon run is in full swing in Hood Canal. Jellyfish aggregations are visible in Budd and Sinclair Inlets — and some of the jellyfish might conceal a beast of another kind within. Oil sheens on the water are currently numerous.

Many creeks and waterbodies in Puget Sound may look pristine, but most face serious threats from stormwater pollution. A new study at Soos Creek shows how mud-dwelling bugs, traditional chemistry and digital "heatmaps" can be used to track stormwater impacts and identify the most polluted areas. Scientists and planners hope that this may one day lower the price tag on costly stormwater fixes. 

Tiny bone samples show that seals alter their diets as conditions change. The findings could help scientists understand whether seals are contributing to local salmon declines.

Last month's federal authorization to kill more than 700 sea lions to protect salmon runs along the Columbia River is prompting discussions of similar actions for harbor seals in Puget Sound. But experts say the situations are very different with many unanswered questions. 

Few environment problems in the Salish Sea have been studied more than the steep decline in salmon populations. But one potential contributor to these declines has gained less attention. Scientists say infectious disease may play a wider role than previously understood.

Design innovations at the new seawall along Seattle's waterfront could inspire improvements for other shoreline structures around Puget Sound. They may even encourage broader regulatory changes that enhance habitat for migrating salmon and other species.

It’s no secret that salmon and other Northwest fish populations are expected to shrink as a result of a warming Pacific Ocean. But a new study suggests that the resulting decline in commercial fishing by 2050 could be twice as great as previously estimated by climate scientists.

As officials struggle to track and contain the outbreak of the novel coronavirus known as COVID-19, ecologists say widespread impacts from viruses and other pathogens are also a growing threat to the species of the Salish Sea ecosystem.

Climate models project that if carbon emmisions continue as they are now, the vast majority of watersheds feeding Puget Sound will receive more rain and far less snow by 2080, causing increased flooding and other dramatic changes to the freshwater ecosystem. We look at the past and possible future of the region's snowpack and what this might mean for salmon and other species — including humans. 

Last summer, scientists met at the University of Washington to address alarming findings concerning the rapid acidification of the world's oceans. Experts at that symposium warned that wildlife in the Salish Sea, from salmon to shellfish, may start to see significant effects from changing water chemistry within the next 10 to 20 years. This article summarizes the symposium's key findings and was commissioned and edited by the Washington Ocean Acidification Center which hosted the gathering. Funds for the article were provided by the Washington state legislature. [A version of this article was originally published by the Washington Ocean Acidification Center.]

The watersheds of Washington’s San Juan Islands were thought to be too small to support wild salmonid populations, and many streams flow only seasonally. But a 2019 article in the journal Conservation Genetics reports that at least five watersheds in the region support populations of coastal cutthroat trout (Oncorhynchus clarki clarki). Genetic analysis of the cutthroat trout in three of the watersheds suggest two support native populations. The findings are important for understanding the conservation status of these previously unknown populations. 

Spring and fall Chinook salmon were thought to be alike until researchers discovered a gene for early migration. Now, federal biologists and legal experts are struggling to decide if spring Chinook should be granted their own legal protection under the Endangered Species Act.

A 2014 paper in the journal PLoS ONE examines differences between foraging behavior of harbor seals based on haulout site locations, seasons, sexes and times of day. The authors hypothesize that these factors may help explain the variability in diet among harbor seals observed at different haul-out site groups in the Salish Sea. 

The Toxics in Fish Implementation Strategy is a recovery plan that will be used to guide funding and activities to reduce the impacts of toxics contaminants on marine fish and the humans that consume them. The plan is scheduled to be completed in 2020.

This three-part series explores opportunities and challenges of using medical interventions to save Puget Sound's southern resident orcas from extinction. Part 1 looks at how scientists might treat endangered southern resident orcas that face starvation and risks of disease; Part 2 considers how veterinarians have intervened with other animals in the wild, and how this might apply to orcas in Puget Sound; and Part 3 explores a federally approved vaccination program designed to ward of a deadly virus among endangered Hawaiian monk seals.

The death of a young female orca in September has sparked a discussion of how and whether scientists should step in with medical care for distressed animals in the wild. Medical intervention has become routine for some endangered mammals, but scientists say Puget Sound’s resident orcas present a series of unique challenges and ethical questions. In part one of our two-part series The Orca Docs we look at how scientists are preparing to treat endangered southern resident orcas that face starvation and risks of disease.

Can scientists bring back the lost tidal forests of Puget Sound? It could take generations, but restoring this rare habitat will pay big dividends for Puget Sound’s salmon.   

A 2018 report from the University of Washington Puget Sound Institute analyzes trends in summer stream flows and finds they are declining, but not necessarily because of abstractions by humans.

An intensive research program in the U.S. and Canada is studying why so few salmon in the Salish Sea are returning home to spawn. It is uncovering a complex web of problems involving predators, prey and other factors that put salmon at risk as they migrate to the ocean. We present a four-part series on the Salish Sea Marine Survival Project, including new findings presented at the 2018 Salish Sea Ecosystem Conference last spring in Seattle.

Chemicals, disease and other stressors can increase a salmon's chance of being eaten or reduce its ability to catch food. We wrap up our series on the Salish Sea Marine Survival Project with a look at some of the lesser-known, but still significant factors contributing to salmon declines in the Salish Sea.

A recent influx of anchovies into Puget Sound may have saved some steelhead from predators, but researchers seek more evidence to prove the connection. Our series on the Salish Sea Marine Survival Project continues with a look at these and other potential impacts from predators on the region's salmon and steelhead.

During June, near normal air temperatures and continued low precipitation have resulted in highly variable freshwater inputs to Puget Sound. A large Noctiluca bloom extends across the South Central Basin of Puget Sound. Coccolithophores are blooming in Hood Canal. Macroalgae is drifting as mats on the water in Port Madison, South Central Basin, and South Sound. They are also piling up on beaches in South and Central Puget Sound and Whidbey Basin. Juvenile fish are migrating out of the estuaries and meeting a complex thermal habitat. New infrared images tell the story. Meet our ocean acidification expert, Stephen Gonski.

Getting bigger faster can help save juvenile Chinook salmon from a gauntlet of hungry predators ranging from birds and marine mammals to larger fish. We continue our series on the Salish Sea Marine Survival Project with a look at what helps salmon grow and prepare for life in the open ocean. 

An intensive research program in the U.S. and Canada is studying why so few salmon in the Salish Sea are returning home to spawn. They are uncovering a complex web of problems involving predators, prey and other factors that put salmon at risk as they migrate to the ocean. We begin a four-part series on the Salish Sea Marine Survival Project, including new findings presented at the 2018 Salish Sea Ecosystem Conference last spring in Seattle. 

A high-profile salmon escape led to a ban on salmon farms in Washington earlier this year. But just across the border, scientists say salmon farms in British Columbia expose migrating fish from Puget Sound to potential maladies like parasites, bacteria and dangerous viruses. They say simply getting rid of salmon farms in Washington does not put the potential impacts to rest. 

As wildlife managers work to recover Puget Sound’s diminished Chinook population, a proposed white paper is expected to review the impacts of some of the salmon's chief predators. The study would include a section on potential management of seals and sea lions, prompting open discussion of a long taboo subject: Could officials seek to revise the Marine Mammal Protection Act — or even conduct lethal or non-lethal removal of seals and sea lions in some cases? Such actions are hypothetical, but we look at some of the ongoing discussions around the issue as prompted by a new resolution from the Puget Sound Leadership Council. 

Researchers are trying to determine which chemicals in stormwater are contributing to the deaths of large numbers of coho salmon in Puget Sound. It has prompted a larger question: What exactly is in stormwater, anyway?

Increased consumption of Chinook salmon by seals and sea lions in the Salish Sea “could be masking the success of coastwide salmon recovery efforts,” according to a new study published in the journal Scientific Reports. Endangered resident orcas are said to be declining in part due to a lack of available Chinook, the orcas' preferred prey.

Formaldehyde is often used to control parasites on hatchery salmon and trout. The U.S. Environmental Protection Agency and the Washington State Department of Ecology conducted a joint study of formaldehyde concentrations in effluent from hatcheries in the Pacific Northwest. 

In recent decades, hundreds of millions of dollars have been spent to restore habitat for Puget Sound salmon. In this article, we look at how scientists are gauging their progress. Are environmental conditions improving or getting worse? The answer may depend on where you look and who you ask.

A biennial report produced by the Governor's Salmon Recovery Office provides stories and data about salmon, habitat, and salmon recovery in Washington, including Puget Sound.

A 2017 report from the Puget Sound Ecosystem Monitoring Program presents an overview of selected recent monitoring and research activities focused on toxic contaminants in the Salish Sea. 

The Puget Sound Ecosystem Monitoring Program (PSEMP) is an independent program established by state and federal statute to monitor environmental conditions in Puget Sound. 

A new approach to flood control is taking hold across Puget Sound. Rivers, scientists say, can be contained by setting them free. Conservationists hope this is good news for salmon recovery.

As threatened Chinook populations in Puget Sound continue to lose ground, the state is looking to new strategies to reverse the trend. In the Skagit watershed, the scientists — and the fish — are among those leading the way. 

A new study shows that increased populations of seals and sea lions are eating far more of Puget Sound’s threatened chinook than previously known, potentially hampering recovery efforts for both salmon and endangered killer whales. 

The Puget Sound Ecosystem Monitoring Program released its fifth annual Marine Waters Overview this week. The report provides an assessment of marine conditions for the year 2015 and includes updates on water quality as well as status reports for select plankton, seabirds, fish and marine mammals.

New techniques for studying orcas have been credited with breakthroughs in reproductive and developmental research. Drones and hormone-sniffing dogs are helping scientists connect declines in food supply with low birth rates and poor health. Update: The research described in this 2016 article has now been published in the 6/29/17 issue of the journal PLOS ONE. 

New, smaller acoustic tags will allow scientists to track steelhead migrations in Puget Sound in ways that were once impossible. Will they provide answers to the mysterious decline of these now-threatened fish? 

The Salish Sea Marine Survival Project has mobilized dozens of organizations in the U.S. and Canada to find an answer to one of the region's greatest mysteries. What is killing so many young salmon before they can return home to spawn? A series of talks at the 2016 Salish Sea Ecosystem Conference brought together some of the latest research. 

Many of Puget Sound's Chinook salmon spend their entire lives in local waters and don't migrate to the open ocean. These fish tend to collect more contaminants in their bodies because of the sound's relatively high levels of pollution. 

A 2015 report from Snohomish County, King County and the Tulalip Tribes outlines protection strategies for salmon and salmon habitat within the Snohomish Basin. 

Researchers are proposing a shift in thinking about how some of the region’s most damaging pollutants enter Puget Sound species like herring, salmon and orcas.

A 2016 paper in Environmental Pollution identifies dozens of pharmaceuticals and other compounds that are accumulating in Puget Sound fish such as salmon.

Food webs are natural interconnections of food chains and depict what-eats-what in an ecological community. While Puget Sound represents a specific food web, the organisms that reside within that web often travel outside the region. In this way, one community's food web can be drastically affected by a change in a neighboring ecosystem.

Decaying organic matter plays an important role in marine ecosystems. 

For close to 100 years, Seattle's Ballard Locks has been one of the region's busiest waterways, drawing major boat traffic along with millions of tourists. But as it prepares to celebrate its centennial, the aged structure is also drawing the concern of engineers. They worry that an earthquake could cause the locks to fail, draining massive amounts of water from Lake Washington and Lake Union. In some scenarios, the two lakes could drop by as much as 20 feet, stranding boats, disabling bridges and causing big problems for salmon restoration.

Chinook, coho and sockeye salmon, along with steelhead trout, live in the Lake Washington watershed and navigate a treacherous route through the Ballard Locks on their way to Puget Sound.

Chinook, coho and steelhead populations in Puget Sound have declined dramatically over the past 30 years. In some cases, counts of fish returning to the rivers are just a tenth what they were in the 1980s. While many possible causes of this decline are under consideration, some researchers are focusing on the combined effects of predators and disease. This article continues our coverage of the ecological impacts of disease in Puget Sound.

The 2015 Puget Sound Fact Book brings together statistics and other information about the health and makeup of the Puget Sound ecosystem. Areas of focus include climate change, geography, water quality, habitats, human dimensions and regional species. The fact book was prepared for the Encyclopedia of Puget Sound with funding from the Environmental Protection Agency and the Puget Sound Partnership.

This report documents how Washingtonians have responded to the challenges of protecting and restoring salmon and steelhead to healthy status. It also serves as a tool to summarize achievements, track salmon recovery progress through common indicators, and identify data gaps that need to be filled.

This 2008 report highlights the vision and accomplishments of ESRP in advancing an ecosystem restoration strategy in Puget Sound to restore the ecosystem processes that are essential for a self-sustaining coastal ecosystem.

This report highlights the vision and accomplishments of ESRP in advancing an ecosystem restoration strategy in Puget Sound to restore the ecosystem processes that are essential for a self-sustaining coastal ecosystem.

Salmon recovery demands both dedication among people with different interests, and sustained resources. This biennial report tells the story of the progress made to date and the challenges ahead.

Scientists say low marine survival rates threaten Puget Sound coho salmon populations. A 2015 article in the journal Marine and Coastal Fisheries reports that wild cohos in the Salish Sea had higher smolt survival rates over a 30 year period than hatchery coho salmon. Smolt survival in the Strait of Georgia during that time declined faster than it did in Puget Sound. 

A 2015 paper presented to the International Whaling Commission compares the impacts of kayaks and powerboats on killer whale populations.

A 2014 King County report projects the capital and maintenance costs of the stormwater treatment facilities that would be needed, within WRIA 9 and the Puget Sound region, to fully comply with the Clean Water Act. 

A December 2014 paper in the journal Aquatic Ecosystem Health & Management describes a project to identify transboundary ecosystem indicators for the Salish Sea. 

Scientists are rethinking floodplain management in Puget Sound. Can we have our farms and salmon too?

The decaying seawall along Seattle’s waterfront is providing scientists with an opportunity to improve long-lost habitat for migrating salmon. It could also show the way for habitat enhancements to crumbling infrastructure worldwide. One University of Washington researcher describes the project.

A 2014 paper decribes how monitoring the energy density of key Pacific salmon species could affect the recovery of northern and southern killer whales through fisheries management.

This 2009 report by the Nisqually Tribe establishes key measures of restoration development, habitat processes, and Chinook salmon response for the largest delta restoration project in the Pacific Northwest.

New research presented at the 2014 Salish Sea Ecosystem Conference shows that some of the greatest dangers to Puget Sound marine life come from our common, everyday activities. These pervasive sources of pollution are so woven into our lives that they are almost invisible to us, but it’s becoming impossible to ignore their effects.

The growth and survival of young salmon in streams, river deltas and floodplains are seen as crucial pieces of the salmon recovery puzzle. In part two of this two-part series, researchers at the Salish Sea Ecosystem Conference in Seattle say the complexities of the salmon life cycle require new coordination among scientists.

Scientists say Puget Sound’s salmon are dying young and point to low growth rates in the marine environment as a possible cause. In part one of this two-part series, scientists consider threats facing young salmon in the open waters of Puget Sound.

Scientists say eelgrass, an unassuming flowering plant found just off shore in Puget Sound, is vital to the health of the ecosystem. They also say the plant is declining. New and increasingly urgent efforts to restore it brought a group of researchers to the 2014 Salish Sea Ecosystem Conference.

A 2014 report describes a study of socio-cultural values associated with blueback salmon in the Quinault Indian Nation. The blueback salmon (Oncorhynchus nerka) is a unique strain of sockeye that returns primarily to the Quinault river system.

Lead Entities are local organizations in Puget Sound that develop salmon recovery strategies and priorities for the region on a watershed-based scale.

An October 2013 report released by the Puget Sound Ecosystem Monitoring Program inventories and assesses monitoring activities of Puget Sound's ESA-listed salmon and steelhead stocks and habitats.

This paper describes a multi-year effort testing whether shoreline enhancements at the Olympic Sculpture Park in Seattle have improved conditions for fish and invertebrates as compared to armored shorelines.

This report, published in 2008 by the Washington Department of Fish and Wildlife, summarizes the economic importance of Washington fisheries using data from 2006. The report's Executive Summary is reprinted below, followed by summaries of data specific to Puget Sound.

The Puget Sound Recovery Implementation Technical Team has released a draft of a NOAA technical memorandum describing frameworks for adaptive management and monitoring of Chinook salmon in Puget Sound. Download the report.

This technical report produced for the Puget Sound Nearshore Partnership on Valued Ecosystem Components (VEC) summarizes existing knowledge of salmon use of nearshore habitats in order to help protect and restore these habitats.

A recent report by an independent science panel reviewed data on the effects of salmon fisheries on Southern Resident Killer Whale populations. The report was released on November 30, 2012 and was commissioned by NOAA Fisheries and Oceans Canada.

The State of Our Watersheds Report is produced by the treaty tribes of western Washington, and seeks to present a comprehensive view of 20 watersheds in the Puget Sound region and the major issues that are impacting habitat.

The Tulalip reservation is located near Marysville, Washington. It was created after the Point Elliott Treaty of 1855, and currently has a population of 2,500 members. The entire tribal population is approximately 4,000 and growing. 

Tulalip Tribes Area of Concern:

The Stillaguamish Tribe is descended from the Stoluck-wa-mish River Tribe, who signed the treaty of Point Elliott in January 1855. Some tribal members moved to the Tulalip reservation, while others remained along the Stillaguamish River. The headquarters for the tribe are in Arlington, Washington.

Stillaguamish Area of Concern:

The Skokomish Tribe began as the Twana Indians, made up of nine communities living in and around the Hood Canal drainage basin.

Skokomish Area of Concern:

The diversity of streams in the county is a reflection of the diversity of its geography. From the small rivulets that begin high in the Cascade Mountains, to the brooks that flow gently across the lowlands, to the five major rivers of the county, there are over 4,800 kilometers (3,000 miles) of perennial streamcourses in King County.

The Puget Sound region has a long history that has shaped the culture and environment we experience today. View a timeline describing key events in the Puget Sound region dating from Washington statehood to the present.

Puget Sound has over 4,000 km (2,500 miles) of shorelines, ranging from rocky sea cliffs to coastal bluffs and river deltas. The exchange of water, sediment, and nutrients between the land and sea is fundamental to the formation and maintenance of an array of critical habitat types.