Basics
Healthy Water Quality
Toxics in Aquatic Life
Indicator
Contaminants in adult salmon
Vital Sign Indicator
Chemical Concentration Wet Weight (ng/g wet weight)
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By 2030, 95% of the samples gathered across Puget Sound habitats exhibit a declining trend of contaminant levels, or are below thresholds of concern for species or human health.

By 2050, 95% of the samples gathered across Puget Sound habitats exhibit contaminant levels below thresholds of concern for species or human health and show no increasing trends.

Target fact sheet

James West
Contributing Partners
Last Updated
7/1/2022 9:31:08 AM
Map
Description
The contaminants in adult Chinook salmon indicator measures levels of two toxic contaminants, PCBs and PBDEs, in edible muscle tissue (fillet) of maturing Chinook salmon that reside in Puget Sound. Levels of PCBs and PBDEs in resident Chinook salmon indicate the amount of these contaminants to which humans and other predators like Southern Resident killer whales may be exposed to when eating these salmon, as well as potential impairments to salmon health that may limit their recovery.
Vital Sign Indicator Chart
Contaminant levels of PCBs and PBDEs in edible muscle tissue (fillet) of resident Chinook salmon from 8 marine areas (MAs), each noted by a unique color, roughly representative of major oceanic basins. Red indicates high contamination, with some salmon (5th percentile or greater) exceeding the human health threshold for that contaminant. Green indicates low contamination, with most salmon (95th percentile or more) below the threshold for that contaminant.

Pacific salmon play an integral part in the ecosystem and culture of Puget Sound, the Salish Sea and across the Pacific Northwest. Toxic chemical contaminants are monitored in adult Chinook salmon because salmon are important food for people, and for the fish, birds and marine mammals who eat these salmon, including Southern Resident killer whales, listed as endangered under the Endangered Species Act (ESA) since 2005. Puget Sound Chinook salmon are also listed as threatened under ESA, and contaminants can potentially impair the health of the salmon themselves, inhibiting recovery of a species at risk of extinction and reducing the food supply to Southern Resident killer whales.

Chinook salmon was chosen as the best salmonid species indicator for the contaminant-risk to people consuming fish from Puget Sound's pelagic (open water) food web because diet and marine distribution of Chinook salmon causes them to accumulate higher contaminant concentrations than the other salmonid species. Specifically, Chinook salmon feed higher trophically than other species, consuming less invertebrates and more fish, resulting in higher levels of contaminants that bio-magnify up the food web. Although Chinook salmon typically migrate to the ocean after leaving their natal rivers, about a third of Puget Sound Chinook salmon remain for much, or all of their lives in Puget Sound, instead of migrating to the ocean (O’Neill and West 2009, Chamberlin et al. 2011). These are called resident Chinook salmon, also known as blackmouth by anglers, and are the focus of this indicator. Resident Chinook salmon support important recreational fisheries in Puget Sound, especially in winter months, however, contaminants in these salmon would potentially pose a health risk to people who consume them.

The highly migratory nature of salmon makes it challenging to understand exactly where they pick up these chemicals; however, monitoring by WDFW’s TBiOS team and others has shown that marine waters, including Puget Sound, are one of the main sources of PCBs and PBDEs in adult salmon (O'Neill and West 2009; Cullon et al. 2009). Resident Chinook salmon were selected for this indicator in part because their contaminant levels are driven mostly by Puget Sound conditions, rather than a mix of Puget Sound and ocean conditions

Key Vital Sign Indicator Results
  • Contaminants measured in resident Chinook salmon in 2016 failed to meet the recovery target for the contaminants in adult Chinook salmon indicator because PCBs were elevated in most of the samples (see target description). For detailed results, see the Interpretation of Results section.
  • PCBs in virtually all resident Chinook salmon from all marine areas exceeded the human health threshold (i.e., the WA Department of Health (DOH) screening value concentration). In contrast, PBDE concentrations in resident Chinook salmon were below the human health thresholds.
  • Although PCB concentrations in resident Chinook salmon were always higher than PBDE concentrations, both PCB and PBDE concentrations were lowest in MA 6 and 7 and tended to increase with distance from cleaner oceanic waters. These data suggest higher contaminant inputs to inner Puget Sound (MAs 10, 8-2, 8-1 and 13), and limited movement of resident salmon between inner and outer Puget Sound, consistent with the results from other studies.
  • Elevated PCB concentrations in resident Chinook salmon (and Pacific herring) above adverse health thresholds, shows us that the Puget Sound pelagic food web is a hot spot for PCBs, and may pose health risk for people and other predators like Southern Resident killer whales who eat these fish.
  • Based on PCB concentrations, DOH advises people to limit their consumption of resident Chinook salmon to no more than two servings per month.
  • In addition to potentially affecting the health of people and predators like Southern Resident killer whales, elevated PCB concentrations in resident Chinook salmon are also high enough to affect the health of salmon themselves, especially those residing in inner Puget Sound (MAs 10, 8-2, 8-1 and 13), potentially reducing the abundance of adult Chinook salmon, thus impacting the food supply available to Southern Resident killer whales, as well as decreasing recreational, commercial, tribal ceremonial and subsistence fishing opportunities.
Methods
Monitoring Program

Washington Department of Fish and Wildlife, Toxics Biological Observation System (TBiOS)

Data Source

Washington Department of Fish and Wildlife, Toxics Biological Observation System (unpublished data)

Resident Chinook salmon were collected from various fishery Marine Areas (MAs) managed by Washington Department of Fish and Wildlife (WDFW), roughly representative of Puget Sound oceanographic basins (see map), in the late fall, winter, spring and late fall of 2016 and 2017. Salmon samples were donated by anglers participating in a winter sport fishery (MAs, 6, 7, 8-1, 8-2, 9, 12 and 13), or collected in a commercial test fishery (MA 10). Because these fish were all collected outside the typical migration timing for ocean-returning adults, they were assumed to be resident Chinook salmon (O’Neill and West 2009, Chamberlin et al. 2011). Moreover, all fish collected for analyses were immature, indicating that the fish were not ocean migrants that had returned to spawn.

Skinless edible muscle tissue (fillet) was collected from the area behind the fish’s head and analyzed for the presence of PCBs and PBDEs, a direct indication of the levels of contaminants people may be exposed to when they eat resident Chinook salmon from Puget Sound. The concentration of contaminants in resident Chinook salmon were compared to DOH’s most current human health screening levels, which are used by DOH as a first step in evaluating whether fish are safe to eat. These screening values also serve as human health threshold concentrations. Concentrations above these screening values or thresholds would trigger concern for high-level consumers (i.e., more than two servings per week).

Critical Definitions
  • Polychlorinated biphenyls (PCBs) are a group of synthetic (man-made) chemicals consisting of 209 compounds, or congeners, each containing a unique number and position of chlorine atoms attached to two phenyl (aromatic) rings. These typically oily compounds were designed for various industrial and residential products and uses (transformers, cable insulation, caulking and plastics) and consist of complex mixtures of congeners. PCBs were largely banned in the US by 1979, but they are still found in materials produced before the ban, as unintentional byproducts of manufacturing, and small amounts (<50 parts per million) are still allowed in products. PCBs are classified as a Persistent Organic Pollutant (POP), because they are resistant to most forms of degradation, and once released to the environment, they can bioaccumulate in organisms and cause adverse health impacts in wildlife and humans.
  • Polybrominated diphenyl ethers (PBDEs) are a group of synthetic (man-made) chemicals consisting of 209 compounds, or congeners (similar to PCBs), although each contain a unique number and position of bromine atoms surrounding two phenyl-ether rings. PBDEs were designed primarily as flame-retardants to prevent or slow the spread of fire in products ranging from electronics and furniture to clothing. In 2008, Washington state banned the sale of select PBDE mixtures, however they can still be found in materials produced before the ban. PBDEs are classified as a POP, because once released to the environment they are resistant to degradation, bioaccumulate in organisms and have adverse health impacts in wildlife and humans.
Interpretation of Results

The current results for toxic chemical contaminants in adult resident Chinook salmon from Puget Sound reveal that the recovery target was not met. PCBs in virtually all salmon from all oceanographic basins exceeded the human health threshold (i.e., 8 ng/g wet weight) based on DOH screening levels considered protective of human health. In contrast, PBDEs measured in salmon from all oceanographic basins of Puget Sound fell below the human health threshold (i.e., 40 ng/g wet weight).

Contaminants in resident Chinook salmon collected from eight marine areas (MAs) in 2016 and 2017. Median concentrations for each MA is noted by a solid horizontal line in the box plot. Box ends represent the 25th and 75th percentile concentrations and diamonds represent the 5th (lower) and 95th (upper) percentile concentrations. The color of the box for each MA is determined by whether the upper diamond is below (green) or above (red) the human health threshold concentration protective of human health (8 ng/g for PCBs and 40 ng/g for PBDEs).

Spatial variation in contaminant concentrations and patterns in resident Chinook salmon also suggest higher inputs of contaminants to inner Puget Sound (MAs 10, 8-2, 8-1 and 13), and limited movement of resident salmon between inner and outer Puget Sound. Although PCB concentrations were higher than PBDE levels in each oceanographic basin, both contaminants tended to increase with distance from cleaner oceanic waters. Concentrations of PCBs and PBDEs were lowest in salmon from the San Juan Islands (MA 7) and the Eastern Strait of Juan de Fuca (MA 6), slightly higher in fish caught further into Puget Sound, including Admiralty Inlet (MA 9), and northern parts of Hood Canal (MA 12), intermediate in the Central (MA 10) and Whidbey Basins (MA 8-1 and 8-2) and highest in fish caught furthest from the ocean in South Basin (MA 13). Increasing contaminant concentrations in salmon in MAs further inward into Puget Sound is consistent with higher contaminant inputs from multiple pathways in those MAs adjacent to more developed landscapes. Indeed, estimated loading (kg/ year) of PCBs and PBDEs to Puget Sound from stormwater surface runoff, wastewater treatment facilities and atmospheric depositions were estimated to be 11 times higher in inner Puget Sound than less developed basins like Hood Canal and Admiralty Inlet (calculated based on Table 3 in Osterberg and Pelletier 2015). Additionally, contaminant patterns in salmon (i.e., relative abundance of contaminant classes) varied spatially between salmon caught in in the San Juan Islands (MA 7) and the Eastern Strait of Juan de Fuca (MA 6) with those in the rest of Puget Sound, indicating limited overlap in their marine distribution (data not shown), consistent with previous salmon tagging studies that documented limited movements between resident Chinook salmon caught in the Strait of Juan de Fuca and the San Juan Islands with those residing in the Central Basin (Arostegui et al. 2017; Kagley et al. 2017). Movement of salmon were evaluated by capturing and tagging resident Chinook salmon with sonic transmitters and then monitoring their movements via detections on various receivers placed throughout Puget Sound. These tracking studies documented a high degree of basin fidelity, with limited movements between resident Chinook caught and tagged in the San Juan Islands and those caught and tagged in the Central Basin (Arostegui et al. 2017; Kagley et al. 2017).

Elevated PCB concentrations in resident Chinook salmon (and Pacific herring) above adverse health thresholds, shows us that the Puget Sound pelagic food web is a hot spot for PCBs, potentially affecting the health of people, Southern Resident killer whales and other wildlife that eat Chinook salmon from Puget Sound. Persistent organic pollutants (POPs) like PCBs enter Puget Sound from multiple pathways (e.g., stormwater, wastewater, air deposition, biological transport and direct spills). Marine organisms accumulate these contaminants, which causes them to increase (or biomagnify) up the food web from zooplankton and forage fish, like Pacific herring, to adult resident salmon, and to people and other top predators like Southern Resident killer whales, that feed primarily on Chinook salmon in the summer months. Based on PCB concentrations in resident Chinook salmon, DOH advises people to limit their consumption of these salmon to no more than two servings per month. PCBs measured in Southern Resident killer whales, especially the subset of whales known to spend more time feeding in Puget Sound (i.e., J-Pod), are also high enough to reduce whale health (Mongillo et al. 2016). Indeed, exposure to contaminants is considered a major threat to recovery of Southern Resident killer whales, along with lack of food, and noise-related disturbances that disrupt feeding success.

Furthermore, resident sub-adult Chinook salmon’s exposure to contaminants may directly hinder the recovery of this ESA-listed species, and indirectly the recovery of Southern Resident killer whales by reducing the supply of food to these whales. PCBs are high enough in some locations to reduce the salmon health, potentially reducing their overall survival or the abundance of adult salmon. Overall, PCB concentrations were high enough to potentially impair their reproduction or growth in 15% of the salmon and cause mortality in 1% salmon sampled in 2016 and 2017, especially those in populations residing in inner Puget Sound (MA 8-1 and 8-2, 10 and 13). Decreases in Chinook salmon abundance caused by contaminant exposure would reduce the food supply of Southern Resident killer whales, as well as decrease recreational, commercial, tribal ceremonial and subsistence fishing opportunities.

Data not available, however time trends should mimic those observed for Toxics in Pacific herring indicator.

A wide range of activities and actions have taken place, are underway, or are planned to address these chemicals, including usage bans, Superfund Site cleanups, sediment remediation, and source monitoring and control. A current evaluation of human activities that contribute to these chemicals in Puget Sound (Results Chains) has been completed by the ongoing Stormwater Strategic Initiative, as well as a prioritization of actions to be funded in the near term to reach the recovery goals defined above. In addition, recommendations to reduce chemical contamination in the prey base supporting Southern Resident killer whales, including Chinook salmon, have been compiled by the Governor’s Orca Task Force.

Please see Implementation Strategies outlined in Toxics in Fish Implementation Strategies to learn more about the development process.

Arostegui, Martin C., Joseph M. Smith, Anna N. Kagley, Dawn Spilsbury-Pucci, Kurt L. Fresh and Thomas P. Quinn. 2017. Spatially clustered movement patterns and segregation of subadult Chinook salmon within the Salish Sea. Marine and Coastal Fisheries 9(1): 1-12. https://doi.org/10.1080/19425120.2016.1249580

Chamberlin, Joshua W., Timothy E. Essington, John W. Ferguson and Thomas P. Quinn. 2011. The influence of hatchery rearing practices on salmon migratory behavior: Is the tendency of Chinook salmon to remain within Puget Sound affected by size and date of release? Transactions of the American Fisheries Society 140(5): 1398-1408. https://doi.org/10.1080/00028487.2011.623993

Cullon, Donna L., Mark B. Yunker, Carl Alleyne, Neil J. Dangerfield, Sandra M. O’Neill, Michael J. Whiticar and Peter S. Ross. 2009. Persistent organic pollutants in Chinook salmon (Oncorhynchus tshawytscha): Implications for resident killer whales of British Columbia and adjacent waters. Environmental Toxicology and Chemistry 28(1): 148-161. https://doi.org/10.1897/08-125.1

Kagley, Anna N., Joseph M. Smith, Kurt L. Fresh, Kinsey E. Frick and Thomas P. Quinn. 2017. Residency, partial migration, and late egress of subadult Chinook salmon (Oncorhynchus tshawytscha) and coho salmon (O. kisutch) in Puget Sound, Washington. NOAA National Marine Fisheries Service Fishery Bulletin 115(4): 544-555.

O'Neill, Sandra M. and James E. West. 2009. Marine distribution, life history traits, and the accumulation of polychlorinated biphenyls in Chinook salmon from Puget Sound, Washington. Transactions of the American Fisheries Society 138(3): 616-632. https://doi.org/10.1577/T08-003.1

Osterberg, David J. and Greg Pelletier. 2015. Puget Sound Regional Toxics Model: Evaluation of PCBs, PBDEs, PAHs, Copper, Lead, and Zinc. Environmental Assessment Program, Washington State Department of Ecology, Olympia, WA. Publication No. 15-03-025 pp. 125 (plus appendices).

Mongillo, Teresa M., Gina M. Ylitalo, Linda D. Rhodes, Sandra M. O'Neill, Dawn P. Noren, and M. Bradley Hanson. 2016. Exposure to a mixture of toxic chemicals: Implications for the health of endangered Southern Resident killer whales. U.S. Dept. Commer., NOAA Tech. Memo. NMFSNWFSC-135, pp. 107. http://doi.org/10.7289/V5/TM-NWFSC-135

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