Dr. Peter S. Ross, Fisheries and Oceans Canada
$ 17,325

Killer whales as sentinels of marine ecosystem contamination

The southern resident killer whale (Orcinus orca) population depends on the availability of prey in the shared coastal waters of Washington state and the province of British Columbia during much of the year. Declining population numbers (down 20% since 1996) have raised concerns in both Canada and the United States, leading to a "threatened" listing in Canada in 1999 and a recent petition to list this population under the terms of U.S. Endangered Species Act (ESA). Reports have cited diminishing prey (salmon) abundance, heavy vessel traffic and high contaminant levels. Contaminants including PCBs have been associated with 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 have initiated a two-year SeaDoc Society project (Year One: 2001; Year Two, this proposal: 2002) 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. In Year One, we initiated a graduate student research project, set up working relationships with several laboratories, conducted preliminary experiments on stable isotopes and fatty acids, collected Chinook smolts and adults from two stocks in Puget Sound, subsampled and prepared tissues for contaminant and other analyses. Contaminant analysis is currently underway. In Year Two, we plan to complete fatty acid and stable isotope analyses, interpret data from these and contaminant analysis in the context of Chinook life history and ecology, killer whale data and food chain structure. This work will help to assess the relative importance of local vs. offshore sources of contaminants. Results will be linked to contaminant data from i) concurrent studies of Strait of Georgia fish; ii) southern resident killer whales; and iii) Puget Sound harbor seals. Results will be further interpreted using multivariate statistical evaluation of contaminant patterns and a 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 U.S. 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.