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Peter S. Ross, Institute
of Ocean Sciences Killer whales as sentinels of marine ecosystem contamination The southern resident killer whale population depends on a viable coastal ecosystem in Washington state and the province of British Columbia. Recent concerns about declining population numbers (down 25% since 1996) have cited diminishing prey (salmon) abundance, heavy vessel traffic and high contaminant levels. Contaminants including PCBs and the pesticide DDT have been associated with numerous adverse health effects in both humans and wildlife, including endocrine disruption, immunotoxicity and reproductive impairment. Our recent report citing northeast Pacific killer whales as among the most contaminated in the world underscores the need to better understand the source of toxic chemicals and their fate in killer whales at the top of the coastal food chain. We propose to evaluate the levels and patterns of Persistent Organic Pollutants (POPs; approximately 250 chemicals, including the PCBs, dioxins and pesticides) in the primary dietary component of southern resident killer whales, Chinook salmon. We will compare contaminant levels and patterns in samples of Chinook as outmigrating smolts and returning adults in an effort to document the source of these contaminants (local vs offshore sources). Data from these analyses will be linked to data generated from two concurrent studies of Strait of Georgia fish (Fraser salmon stocks, English sole and Pacific herring) and southern resident killer whales, thereby strengthening their interpretation in an ecosystem perspective. Results will be interpreted in the context of food chain structure using several tools (e.g. stable isotope analysis, fatty acid signature analysis, multivariate statistical evaluation of contaminant patterns and food chain bioaccumulation model). Results will also be related to our ongoing research into the effects of POPs on the health of killer whales. This project will help to "bridge" Canadian and US approaches to assessing contaminant levels in shared waters. Results from this research will be provided to stakeholders by way of a dedicated website and a published "fact sheet". In this manner, we plan to better understand the state of contamination of the marine ecosystem in Puget Sound, the Strait of Georgia and Juan de Fuca Strait, and the risk that this contamination presents to killer whales and other high trophic level consumers. |