Space Use Patterns and Population Trends of Southern Resident Killer Whales in Relation to Distribution and Abundance of Pacific Salmon
Killer whales (Orcinus orca) are long-lived top predators occurring in relatively low densities throughout their range (Dahlheim and Matkin 1994). As such, they have been viewed as indicators of ecosystem health and have become the focus of intensive study (Heimlich-Boran 1986). A population of killer whales in the Northeast Pacific, known as the southern resident community (SRC), has drawn considerable interest due to its proximity to urban areas, a long-term survey program on the population, and a recent decline in numbers that has led to the listing of the SRC as an Endangered Species under the US Endangered Species Act of 1973 as amended (ESA), the Canadian Species at Risk Act (SARA), and Washington State law (Baird 2001; Wiles 2004; NMFS 2005). A number of factors have been identified as possible causes in the recent decline of the SRC, including anthropogenic disturbance, high concentrations of contaminants, and a reduction in quality or quantity of preferred prey (Baird 2001; Krahn et al. 2002; Wiles 2004). This study investigates the relationship between the SRC and Pacific salmon (Oncorhynchus spp.) to better understand prey associations and to provide useful information for management actions. Link
