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WA5 Wildlife Toxicology: Forensic Approaches
() Endangered NE Pacific southern resident killer whales are at risk for contaminant-related health impacts.
Ross, P.1, Ford, J.1, Jeffries, S.2, Calambokidis, J.3, 1 Fisheries and Oceans Canada, Sidney, BC, Canada2 Washington Department of Fish and Wildlife, Tacoma, WA, USA3 Cascadia Research, Olympia, WA, USA
ABSTRACT- The southern resident killer whales (Orcinus orca) frequent the coastal waters of British Columbia (BC)- Washington State and represent a small (n=84), reproductively isolated population. Listed as endangered by Canada and the State of Washington, they face three major threats: historical declines in the abundance of prey (salmon), heavy boat traffic (noise and disturbance) and very high levels of toxic chemicals such as polychlorinated biphenyls (PCBs). A 20% population decline between 1996 and 2001 underscored conservation concerns about these killer whales and galvanized a number of mitigative strategies. We have been conducting research on the effects of persistent organic pollutants (POPs) on the health of free-ranging marine mammals in BC and Washington. Our transboundary research suggests that POPs are affecting the immune and endocrine systems of another marine mammal species: the harbour seal (Phoca vitulina). Conducting toxicological research on free-ranging killer whales is more problematic. We are using small skin-blubber biopsy samples to assess the health of endocrine and immune systems of killer whales; preliminary results indicate that several health-related endpoints are quantifiable in these biopsies. Given the highly conserved nature of many of the physiological endpoints that are disrupted by POPs in vertebrates, we argue that a combined weight of evidence provides the best direction for managers tasked with conservation of southern resident killer whales. We suggest that current levels of PCBs in these killer whales represent a tangible threat to their health, and may lead to diminished reproductive performance, neurological deficits and increased susceptibility to disease. While the legacy of PCBs continues to present health risks to these killer whales, concentrations have declined since the advent of regulations in the mid-1970s. Aspects of industrial, consumer and agricultural chemical design, use and disposal must therefore be included in the implementation of an effective recovery plan for this population.
Key words: persistent organic pollutants, killer whale, toxicology, endangered
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