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Monitoring pregnancy impacts on Southern Resident Killer Whales

Southern Resident Killer Whales (SRKWs) frequent the Salish Sea, and their population was heavily harvested by the aquarium industry during much of the 1960’s. The harvest significantly impacted the reproductive/age structure of the population along with the ability to reproductively recover from population declines following harsh years. The population then experienced an unexplained 20% decline in the late 1990s, suggesting that this ecosystem may be unable to sustain these apex predators. The SRKW population was listed in 2001 as endangered under Canada’s Species at Risk Act and in 2005 under the U.S. Endangered Species Act. This team of researchers has a long-standing study to evaluate three major proposed threats to the SRKW population: reduced prey availability due to precipitous salmon declines, excessive exposure to environmental contaminants due to biomagnification of toxicants up the food chain, and disturbance from private and commercial whale watch boats. Recent work has focused on how the above pressures impact pregnancy success in SRKW, owing to the overwhelming impact that pregnancy success has on population growth. Funding for this project supported a summer season of fieldwork to maintain continuity in sampling for this research.

The method for measuring the effects of these threats on killer whales is collection of fecal material located by detection dogs, and subsequent laboratory analysis to genetically identify individuals and measure pregnancy status (reproductive hormones), nutritional status (thyroid hormones) hormones, stress (glucocorticoid hormones) and environmental contaminants. During the 2014 season, sampling was conducted from June through October in the Salish Sea, concentrating on the Haro Strait, the Strait of Georgia and the western portion of the Strait of Juan de Fuca. A total of 60 southern resident fecal samples were collected during approximately 100 hours of active sampling in the presence of the whales. Our goal was to acquire samples from all whales (current population is 78 animals). However, special emphasis was placed on sampling reproductive age females during the 2014 field season. Laboratory analysis of the samples is currently underway. ($9,930)