Investigators: Dr. Leigh Torres, Leila Lemos, Dr. Joe Haxel, Sharon Nieukirk, Todd Chandler
Cetaceans are acoustically active, dependent on, and sensitive to the surrounding soundscape. Therefore, understanding the scales, intensities and types of impacts from ocean noise on their ecology and populations is a critical step toward improved management and protection. Studies have shown behavioral impacts on various cetacean species from acute ocean noise events, such as seismic air guns, mid-frequency sonar and elevated vessel traffic. Yet, it is unclear how chronic, elevated ambient noise levels may affect the physiology, behavior and ecology of individuals, or how these impacts may translate into biologically significant events with long-term consequences for individuals or populations (e.g., the Population Consequences of Acoustic Disturbance (PCAD) model).
In 2015, the GEMM Lab initiated a multifaceted and non-invasive research project to evaluate the hormonal variability and health of gray whales that forage along the Oregon coast between May and October each year. These whales are part of the Pacific Coast Feeding Group (PDFG) and forage in the coastal habitat off Oregon, where they are exposed to variable ambient ocean noise conditions (e.g., storms, vessel traffic).
Our objectives are to (1) measure and characterize the coastal soundscape of Oregon, (2) describe the variation in reproductive and stress hormones in gray whale fecal samples, (3) evaluate the trends in gray whale body condition by demographic unit and temporal period, (4) assess the annual variation in prey availability and quality for gray whales, and (5) link these previously described data sets and results to evaluate the relationships between ambient ocean noise levels and gray whale health.
In this study we use a combination of methods to link whale stress with varying ambient sound level conditions. We monitor coastal ambient ocean noise using hydrophones, assess stress levels in gray whales through fecal sample collection and analysis, use drones to document whale behavior and body condition, and deploy GoPro camera drops and collect zooplankton samples to describe prey availability.
Findings from our project will be used to inform management decisions regarding allowable noise thresholds in the vicinity of baleen whale habitats, aiding species conservation.
Cetaceans are acoustically active, dependent on, and sensitive to the surrounding soundscape. Therefore, understanding the scales, intensities and types of impacts from ocean noise on their ecology and populations is a critical step toward improved management and protection.