Sandra M. O'Neill

PERSISTENT ORGANIC POLLUTANTS IN CHINOOK SALMON (ONCORHYNCHUS TSHAWYTSCHA): IMPLICATIONS FOR RESIDENT KILLER WHALES OF BRITISH COLUMBIA AND ADJACENT WATERS

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.

Marine Distribution, Life History Traits, and the Accumulation of Polychlorinated Biphenyls in Chinook Salmon from Puget Sound, Washington

Abstract Polychlorinated biphenyl (PCB) levels and the factors affecting PCB accumulation in subadult and maturing Chinook salmon Oncorhynchus tshawytscha from Puget Sound were characterized. Specifically, we (1) determined PCB levels in Chinook salmon from Puget Sound and compared them with levels in Chinook salmon from other West Coast populations, (2) determined whether PCB accumulation mainly occurred in the freshwater or marine habitats, and (3) quantified the relative importance of fish age, fish size (fork length), lipid content, and saltwater age (the number of winters spent in saltwater) on PCB concentration. The average PCB concentration measured in skinless muscle tissue samples of subadult and maturing Chinook salmon collected from Puget Sound was 53 ng/g (wet weight), which was 3-5 times higher than those measured in six other populations of Chinook salmon on the West Coast of North America. Concentrations in the Puget Sound samples varied from 10 to 220 ng/g. A comparison of PCB body burdens...

An evaluation of background levels and sources of polycyclic aromatic hydrocarbons in naturally spawned embryos of Pacific herring (Clupea pallasii) from Puget Sound, Washington, USA

Pacific herring embryos spawned in nearshore habitats may be exposed to toxic contaminants as they develop, from exogenous sources in spawning habitats and from maternal transfer. Determining baseline concentrations of these toxic contaminants is important for evaluating the health of this species, especially during this sensitive life stage. In this study we compared concentrations of polycyclic aromatic hydrocarbons, or PAHs, in naturally spawned herring embryos from five spawning areas across Puget Sound. The summed values of 31 PAH analytes (Σ31PAH) in early- to late-stage development embryos ranged from 1.1 to 140 ng/g, wet weight. Σ31PAH concentrations increased with development time in embryos from one spawning area where the greatest concentrations were observed, and the relative abundance of PAH chemicals in late-stage embryos was similar to those in nearby sediments, suggesting accumulation from local environmental sources. PAHs in both sediments and late-stage embryos appeared to exhibit a pyrogenic pattern. Although maternal transfer of PAHs appeared to be a negligible source to embryos in spawning areas with the greatest embryo PAH concentrations, maternal transfer may have been the dominant source in embryos from spawning areas where the lowest levels of embryo-PAHs occurred. Chronic embryo mortality has been reported in spawning habitats where we observed the greatest concentration of PAHs in embryos, and necrotic tissue in herring embryos from one such location was similar in description to phototoxic PAH necrosis reported elsewhere for embryonic zebrafish.

English Sole Spawning Migration and Evidence for Feeding Site Fidelity in Puget Sound, U.S.A., with Implications for Contaminant Exposure

Abstract English sole is used as a sentinel species for contaminant studies in Puget Sound because it is abundant, easily sampled, and broadly distributed in the northwestern United States. Moreover, this species exhibits a number of well-documented effects of polycyclic aromatic hydrocarbon (PAH) exposure. To assess the potential for contaminant exposure during spawning migrations and to track the localized movements of adult English sole in the vicinity of Eagle Harbor, we used acoustic telemetry. In August 2007, we collected 19 English sole from Eagle Harbor, a small embayment of Puget Sound with a long history of PAH contamination and subsequent remediation actions. Fish were surgically implanted with uniquely-coded acoustic transmitters and their movements were tracked via an array of eight submersible receivers inside Eagle Harbor and near its entrance. In addition, we obtained detection data from over 70 other receivers throughout Puget Sound that were maintained by a consortium of regional researchers. All tagged fish were detected immediately after release, and 18 were detected outside of Eagle Harbor at a variety of locations in Puget Sound. Some of these fish made rapid movements across the sound and traveled minimum distances of 32 to 106 km. Half of the fish detected outside Eagle Harbor returned to their capture site in spring 2008, approximately eight months after tagging. This fidelity to summer feeding habitats has important implications for both contaminant studies and flatfish management. In addition, our results illustrate the power of data sharing and the value of pooling resources to maintain large arrays of acoustic receivers.