View in Vital Signs- Healthy Water Quality
- Toxics in Aquatic Life
- Indicator
- Contaminants in juvenile salmon
- Vital Sign Indicator
- Chemical Concentration Lipid Weight (ng/g lipid 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.
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Andrea Carey
- Contributing Partners
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- Last Updated
- 5/23/2022 12:14:28 PM
Pacific salmon play an integral part in the ecosystem and culture of Puget Sound, the Salish Sea and across the Pacific Northwest. However, Puget Sound Chinook salmon have been listed as a threatened species under the Endangered Species Act (ESA) since 1999 because of habitat loss and degradation, climate change, and overfishing. More recently, contaminants have been recognized as a threat to ESA-listed Chinook salmon (NMFS 2016), especially for juveniles that may be exposed to multitudes of toxic chemical contaminants as they migrate through rivers, estuaries and nearshore habitats on their way to feed in the Pacific Ocean. The physiological challenge of moving from fresh to saltwater makes juvenile salmon susceptible to stressors, including contaminants. Compared to other salmon species, juvenile Chinook salmon are especially vulnerable to a wide variety of contaminants because they rear and feed longer in estuaries, which are receiving waters for many toxic contaminants. Exposure to contaminants above fish health threshold levels can cause adverse health effects such as altered hormone production, reduced growth and increased disease susceptibility, all of which can reduce survival and prevent recovery of this ESA-listed species.
- The contaminants in juvenile Chinook salmon indicator failed to meet the recovery target (see target description) because both PCB and PBDE levels in juvenile Chinook salmon exceeded the fish health thresholds from at least one location. For detailed results, see the Interpretation of Results section.
- PCB levels exceeded the fish health threshold in juvenile Chinook salmon from four of the 11 river estuaries (Snohomish, Duwamish/Green, Puyallup and Nisqually), and Lake Washington, all sites surrounded by moderately or highly developed land (with more than 25% impervious surface). Juvenile Chinook salmon from all remaining river estuaries had PCBs below the fish health threshold.
- PBDE levels exceeded the fish health threshold in juvenile Chinook salmon from the Snohomish and Puyallup Rivers, two rivers where PCBs were also elevated. In the remaining nine river estuaries and Lake Washington, PBDE levels were below the fish health threshold.
- Both hatchery- and natural-origin Chinook salmon were exposed to contaminants. In some instances, natural-origin salmon had higher contaminant levels (O’Neill et al. 2020), likely due to their extended use of estuarine habitats compared to hatchery-origin salmon.
- Contaminant-related health risks for ESA-threatened Chinook salmon were widespread in developed watersheds in central and south Puget Sound where contaminant levels were high enough to potentially adversely affect salmon health and reduce their survival.
- Contaminants in juvenile Chinook salmon above fish health thresholds may reduce the abundance of returning 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.
- Evaluation of the progress towards the recovery target relies on a comparison of current and previous contaminant levels to identify trends over time for this indicator. Currently, trend data is pending for a select number of sites and will be updated in the near future.
- Monitoring Program
Washington State Department of Fish and Wildlife, Toxics Biological Observation System (TBiOS)
- Data Source
Washington State Department of Fish and Wildlife, Toxics Biological Observation System (unpublished data)
In 2016, juvenile Chinook salmon were collected from the estuaries of 11 Puget Sound rivers and Lake Washington. These sampling locations represent the major pathways through which ESA-listed Chinook salmon migrate to Puget Sound. Juvenile salmon were collected using beach seines operated by state, county, tribal and federal biologists, working collaboratively with WDFW. These 12 sampling locations also represent a wide range of watershed development in Puget Sound, noted by percent impervious surface (% IS) on the map. The % IS in watersheds was determined by overlaying % IS land cover data from the 2016 National Land Cover Dataset (NLCD) onto predefined, watershed catchment areas adjacent to the Puget Sound shoreline. The NLCD Percent Developed Imperviousness dataset uses Landsat satellite data with a spatial resolution of 30 meters (Homer et al. 2020). The watershed catchment areas were originally developed by Washington Department of Ecology for another purpose (Stanley et al. 2016) but were determined to be of a size appropriate for use in this study (median area of 8.8 km2 or 3.4 mile2).
Whole bodies of juvenile Chinook salmon were analyzed for PCBs and PBDEs using analytical methods described in O’Neill et al. (2020). Levels measured in the whole bodies are an indication of the amounts of contaminants the salmon are exposed to during their migration from freshwater to Puget Sound. These levels were then compared to adverse fish health effects thresholds determined in laboratory exposure studies of PCBs (2,400 ng/g lipid) reported by Meador et al. (2002) and PBDEs (470 ng/g lipid, calculated as the sum of PBDE-47 and PBDE-99) based on interpretations of studies by Arkoosh et al. (2010, 2013 and 2018) described in O’Neill et al. (2015). These two individual PBDE congeners account for the majority of PBDEs detected in juvenile Chinook salmon from Puget Sound. Laboratory studies have used these two congeners when determining how PBDEs affect the health of juvenile Chinook salmon. In particular, these adverse effect concentrations have been shown to negatively affect the health of salmon by altering hormone function, reducing growth and increasing susceptibility to disease. Concentrations measured above these fish health thresholds may reduce salmon’s survival.
PCBs and PBDEs are lipophilic, or fat-loving contaminants, meaning they tend to accumulate in the lipids of plants and animals. Further, the toxicity of these contaminants, or the amount of harm they cause, is related to the salmon’s tissue lipid levels, where toxicity increases with declining lipids. Lipid levels in juvenile Chinook salmon vary widely, but they all typically decline to approximately 1% or less during their migration through estuaries. Because individual salmon were collected at different phases of their migration, and had varying lipid levels, we calculated lipid weight PCB and PBDE concentrations for all salmon at 1% lipids, providing an estimate of potential toxicity at a consistent, low lipid level that all juvenile Chinook salmon typically experience during their seaward migration.
- 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.
The current results for the toxic contaminants in juvenile Chinook salmon indicator did not meet the recovery target because most samples (calculated as the 95th percentile) did not have concentrations of both PCBs and PBDEs that were below the fish health thresholds for these contaminants. PCB concentrations in juvenile Chinook salmon exceeded the fish health threshold (2,400 ng/g lipid) in four of the 11 Puget Sound river estuaries assessed (Snohomish, Duwamish, Puyallup, and Nisqually rivers), as well as in Lake Washington, through which several Chinook salmon populations migrate to reach Puget Sound. PBDEs in juvenile Chinook salmon also exceeded the fish health threshold (470 ng/g lipid) in two of these sampling locations, the Puyallup and the Snohomish river estuaries. In all other sampling locations, contaminants in juvenile Chinook salmon were below the PBDE fish health thresholds.
Exposure to PCBs and PBDEs above fish health threshold concentrations may affect juvenile salmonid behavior, alter hormone function, reduce growth and immuno-competence, increase susceptibility to disease (see Methods), and ultimately reduce their survival. Both hatchery- and natural-origin salmon were exposed to contaminants during their seaward migration to Puget Sound. However, in some instances natural-origin salmon had higher contaminant levels than hatchery-origin salmon (O’Neill et al. 2020), likely due to extended use of estuarine habitats for feeding and growing by natural-origin salmon. Regardless of their origin, contaminant exposure above fish health threshold concentrations put salmon at increased risk. A previous study documented that juvenile hatchery Chinook salmon transiting contaminated Puget Sound estuaries between 1972 and 2008, where they would have been exposed to PCBs, PBDEs and other contaminants, exhibited an overall rate of survival that was 45% lower than that for Chinook salmon moving through uncontaminated estuaries (Meador 2014).
Contaminant-related health risks for ESA-threatened Chinook salmon populations were widespread in developed watersheds, all of which were located in central and south Puget Sound, where most of the anthropogenic development has taken place. These results are consistent with a previous WDFW study evaluating contaminants in juvenile Chinook salmon from a smaller number of rivers (O’Neill et al. 2015). Moreover, accumulation of PCBs, and to a lesser extent PBDEs, in seaward migrating juvenile Chinook salmon appears to be related to the type of land cover in their natal rivers. Juvenile Chinook salmon migrating through these developed watersheds, typically with greater than 25% impervious surface, accumulated more PCBs than those moving through less developed watersheds.
A study to evaluate contaminant sources and pathways in juvenile Chinook salmon from the Snohomish River used contaminant fingerprints and stable isotopes measured in whole body salmon samples to attribute elevated PCBs to stormwater, whereas elevated PBDE concentrations were attributed to discharges of wastewater treatment plants, with concentrations high enough to pose a conservation threat (O’Neill et al. 2020). More broadly, stormwater surface runoff was identified as the primary pathway for PCBs to enter Puget Sound (Osterberg and Pelletier 2015) and were greater in developed watersheds with higher percentages of impervious surfaces. In contrast to PCBs, the loadings of PBDEs to Puget Sound are primarily associated with atmospheric deposition and discharges from wastewater treatment plants, but stormwater was identified as a secondary source (Osterberg and Pelletier 2015), with higher loadings in developed watershed where more people live.
As salmon migrate downriver through developed watersheds towards marine waters, they consume contaminated prey or absorb contaminants across skin and gill tissues. Movement through contaminated estuaries is of particular concern for the health of juvenile Chinook salmon because they are undergoing the energy-demanding process of transitioning from fresh to saltwater, and their fat, or lipids, are changing rapidly. The toxicity of some contaminants (e.g., PCBs and PBDEs) is directly related to their levels of body fat because these chemicals tend to accumulate in lipids, where they cause less harm. However, as juveniles burn fat, these chemicals are re-released into the blood stream where they can cause more harm.
Collectively, the Chinook salmon from these more developed watersheds contribute to the productivity of two major population groups of Puget Sound Chinook salmon (Central Eastern and South). Contamination of juvenile Chinook in these river systems may contribute to population declines and prevent recovery of this threatened species. This has broad implications for management and conservation efforts, as well as contaminant remediation and reduction. In particular, contaminant remediation in watersheds in central and southern Puget Sound may be necessary for successful recovery of Central Eastern and South major population groups of Chinook salmon in Puget Sound. Habitat restoration efforts to enhance salmon populations should assess potential contaminant inputs and possible remediation, if needed, to maximize restoration and ensure safe salmon habitats. Additional in-depth studies to determine the location and source of contaminant exposure for natural- and hatchery-origin Chinook salmon migrating seaward through developed watersheds are underway for Chinook salmon originating from the Duwamish River and planned for the Puyallup River. Results from these studies will help to prioritize management actions to reduce contaminant threats and ultimately, improve the health of these salmon.
Recovery of Southern Resident killer whales and Chinook salmon, two icons of the Pacific Northwest, may be hindered by juvenile Chinook salmon’s exposure to contaminants. Contaminants in juvenile Chinook salmon above fish health thresholds potentially reduce their survival and ultimately may lower the abundance of returning adult Chinook salmon to Puget Sound. Southern Resident killer whales (SRKWs), an ESA-listed endangered species, primarily feed on adult Chinook salmon. Decreases in Chinook salmon abundance caused by contaminant exposure would reduce the SRKW’s food supply, potentially affecting their health and survival. In recent years, reduced numbers of returning Chinook salmon to the Salish Sea and other locations along the west coast of North America has been identified as one of the factors contributing to the SRKWs population decline. Lastly, low abundance of returning Chinook salmon to Puget Sound also decreases recreational, commercial, tribal ceremonial and subsistence fishing opportunities, a vital part of Washington’s culture and economy.
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There are no changes to this indicator. Trends data is pending for selected sites and will be updated in the near future.
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 have been compiled by the Governor’s Orca Task Force.
Please see Implementation Strategies outlined in the Toxics in Fish Implementation Strategy for additional details.
Arkoosh, Mary R., Deborah Boylen, Joseph Dietrich, Bernadita F. Anulacion, Gina M. Ylitalo, Claudia F. Bravo, Lyndal L. Johnson, Frank J. Loge and Tracey K. Collier. 2010. Disease susceptibility of salmon exposed to polybrominated diphenyl ethers (PBDEs). Aquatic Toxicology 98(1): 51-9. https://doi.org/10.1016/j.aquatox.2010.01.013
Arkoosh, Mary R., Joseph Dietrich, Gina M. Ylitalo, Lyndal L. Johnson, and Sandra M. O’Neill. 2013. Polybrominated diphenyl ethers (PBDEs) and Chinook salmon health. U.S. Department of Commerce. National Oceanic and Atmospheric Association, National Marine Fisheries Service, Northwest Fisheries Science Center, Newport, Oregon. 49 pp. plus Appendices.
Arkoosh, Mary R., Ahna L. Van Gaest, Stacy A. Strickland, Greg P. Hutchinson, Alex B. Krupkin, Mary Beth Rew Hicks and Joseph P. Dietrich. 2018. Dietary exposure to a binary mixture of polybrominated diphenyl ethers alters innate immunity and disease susceptibility in juvenile Chinook salmon (Oncorhynchus tshawytscha). Ecotoxicology and Environmental Safety 163: 96-103. https://doi.org/10.1016/j.ecoenv.2018.07.052
Homer, Collin, Jon Dewitz, Suming Jin, George Xian, Catherine Costello, Patrick Danielson, Leila Gass, Michelle Funk, James Wickham, Stephen Stehman, Roger Auch and Kurt Riitters. 2020. Conterminous United States land cover change patterns 2001–2016 from the 2016 National Land Cover Database. ISPRS Journal of Photogrammetry and Remote Sensing 162: 184–199. https://doi.org/10.1016/j.isprsjprs.2020.02.019
Meador, James P., Tracey K. Collier and John E. Stein. 2002. Use of tissue and sediment-based threshold concentrations of polychlorinated biphenyls (PCBs) to protect juvenile salmonids listed under the U.S. endangered species act. Aquatic Conservation: Marine and Freshwater Ecosystems 12: 493-516. https://doi.org/10.1002/aqc.523
Meador, James P. 2014. Do chemically contaminated estuaries in Puget Sound (Washington, USA) affect the survival rate of hatchery-reared Chinook salmon? Canadian Journal of Fisheries and Aquatic Sciences 71(1): 162-180. https://doi.org/10.1139/cjfas-2013-0130
NMFS (National Marine Fisheries Service). 2016. 2016 5-Year Review: Summary & Evaluation of Puget Sound Chinook Salmon, Hood Canal Summer-run Chum salmon, Puget Sound Steelhead. NMFS West Coast Region, Portland, OR.
O'Neill, Sandra M., Andrea J. Carey, Jennifer A. Lanksbury, Laurie A. Niewolny, Gina Ylitalo, Lyndal Johnson and James E. West. 2015. Toxic contaminants in juvenile chinook salmon (Oncorhynchus tshawytscha) migrating through estuary, nearshore and offshore habitats of Puget Sound. Olympia, WA. Washington Department of Fish and Wildlife. Technical Report FPT 16-02. 132 pp.
O’Neill, Sandra M., Andrea J. Carey, Louisa B. Harding, James E. West, Gina M. Ylitalo and Joshua W. Chamberlin. 2020. Chemical tracers guide identification of the location and source of persistent organic pollutants in juvenile Chinook salmon (Oncorhynchus tshawytscha), migrating seaward through an estuary with multiple contaminant inputs. Science of the Total Environment 712, 135516. https://doi.org/10.1016/j.scitotenv.2019.135516.
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).
Stanley, Stephen, Susan Grigsby, Derek Booth, David Hartley, Richard Horner, Tom Hruby, Jennifer Thomas, Pam Bissonnette, Robert Fuerstenberg, Joan Lee, Patricia Olson and George Wilhere. 2016. Puget Sound Characterization. Volume 1: The Water Resources Assessments (Water Flow and Water Quality). Washington State Department of Ecology. Publication No. 11-06-016. Olympia, WA. pp. 75.
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