title: Persistent organic pollutants in chinook salmon (Oncorhynchus tshawytscha): implications for resident killer whales of British Columbia and adjacent waters.
abstract: We measured persistent organic pollutant (POP) concentrations in chinook salmon (Oncorhynchus tshawytscha) in order to characterize dietary exposure in the highly contaminated, salmon-eating northeastern Pacific resident killer whales. We estimate that 97 to 99% of polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), dichlorodiphenyltrichloroethane (DDT), and hexachlorocyclohexane (HCH) in returning adult chinook were acquired during their time at sea. Highest POP concentrations (including PCBs, PCDDs, PCDFs, and DDT) and lowest lipids were observed in the more southerly chinook sampled. While feeding by salmon as they enter some more POP-contaminated near-shore environments inevitably contribute to their contamination, relationships observed between POP patterns and both lipid content and delta13C also suggest a migration-related metabolism and loss of the less-chlorinated PCB congeners. This has implications for killer whales, with the more PCB-contaminated salmon stocks in the south partly explaining the 4.0 to 6.6 times higher estimated daily intake for sigmaPCBs in southern resident killer whales compared to northern residents. We hypothesize that the lower lipid content of southerly chinook stocks may cause southern resident killer whales to increase their salmon consumption by as much as 50%, which would further increase their exposure to POPs.
authors.affiliation: Institute of Ocean Sciences, Fisheries and Oceans Canada, P.O. Box 6000, 9860 West Saanich Road, Sidney, British Columbia, V8L 4B2.
authors.forename: Donna L
authors.initials: DL
authors.lastname: Cullon
authors.forename: Mark B
authors.initials: MB
authors.lastname: Yunker
authors.forename: Carl
authors.initials: C
authors.lastname: Alleyne
authors.forename: Neil J
authors.initials: NJ
authors.lastname: Dangerfield
authors.forename: Sandra
authors.initials: S
authors.lastname: O'Neill
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Whiticar
authors.forename: Peter S
authors.initials: PS
authors.lastname: Ross
mesh_terms: D000818:Animals; D001822:Body Burden; D001955:British Columbia; D005247:Feeding Behavior; D012474:Salmon / Q000378:metabolism*; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000378:metabolism* / Q000633:toxicity; D050685:Whale, Killer
chemical_list: D014874:Water Pollutants, Chemical