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.
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
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).
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).
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.
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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