Southern Resident Killer Whale Noise and Disturbance Research
Assessing the impacts of noise and vessel disturbance on endangered Southern Resident killer whales.
Disturbance from vessels and underwater noise is a significant risk factor of Southern Residents. We assess the impacts of vessel presence and noise using various approaches in the whale's summer range, Washington’s inland waters.
Understanding the Noisy Underwater Environment
Our initial work focused on determining ambient noise conditions and developing sound propagation models for the whales’ summer range. We investigated changes in individual behavior (Noren et al. 2009, Williams et al. 2009), group activity state (Lusseau et al. 2009), and changes in acoustic behavior (Holt et al. 2009) in the presence of boats and increased underwater noise levels. We also measured the metabolic cost (how much energy the whales used) of specific behavioral and acoustic responses to vessel disturbance. We used the results to assess the cumulative energetic costs of Southern Residents to vessel disturbance.
Results from these behavioral and energetic studies informed protective regulations. We will model the effects of vessel disturbance on the Southern Residents’ body condition in the future.
Studying Impacts on Southern Residents' Behavior
Our current work looks at vessel and noise effects on the Southern Residents’ foraging behavior. We use suction-cup mounted acoustic recording tags combined with geo-referenced locations of vessels nearby to note any changes in feeding behavior and success.
We also are characterizing the soundscapes in Southern Residents’ habitat. This work includes evaluating trends in anthropogenic noise inputs (e.g., commercial fishing, ferries) in the Southern Residents' critical habitat.
These ongoing studies contribute to evaluating vessel and noise impacts on Southern Residents, which Federal and state agencies use to inform the evaluation of existing protective measures and potential amendment of the vessel regulations to protect killer whales.
Marla Holt, Marine Mammal Ecology Team