PROJECTS
Introduction & Objectives
Harbor porpoises (Phocoena phocoena) are the most abundant cetaceans in Hood Canal waters, yet they remain a data-deficient species that can be challenging to detect and monitor. Harbor porpoises are a species of interest for the U.S. Navy because they are sensitive to very high frequency underwater sounds and could be impacted by naval activities occurring within the Northwest Training and Testing (NWTT) Dabob Bay Range Complex (DBRC) in Hood Canal, WA. This project is aimed at building the framework for a long-term monitoring program to improve our understanding of harbor porpoise presence and distribution patterns on Navy ranges, and to serve as baseline data for future behavioral response studies (BRS).
Technical Approach
Four locations in the DBRC were selected as long-term PAM survey sites. Full-bandwidth, autonomous recorders were deployed at the survey sites four times during 2025 (February, May, August, and October) for approximately 4 – 6 weeks per deployment. The acoustic data were processed using a custom-built harbor porpoise click detector to identify echolocation clicks contained within each recording. Data processing and preliminary analysis for the 2025 dataset is currently ongoing. In 2026 we will use this dataset to describe harbor porpoise seasonal occurrence in Hood Canal. We also plan to explore the relationships between harbor porpoise click activity and other variables (e.g. temporal, spatial, and environmental) as potential indicators/predictors of presence.
Progress & Results
Analysis of the 2025 SoundTrap data is currently ongoing. Descriptive statistics will be performed to identify patterns of harbor porpoise occurrence and how it varies across seasons. Diel patterns of click activity at each site will be examined to understand when harbor porpoises are most active throughout the day. Spatial differences in porpoise activity levels across the monitoring sites will be used to identify hotspots. These areas of high activity will be important for continued monitoring and could serve as valuable indicators for future BRS studies in Hood Canal. Additionally, we plan to investigate the potential relationships between porpoise activity and environmental variables using a generalized additive mixed-model (GAMM) which could include tidal and bathymetry data (NOAA), diel phase data (ONR), and other environmental variables. Data aggregation for this model is currently ongoing.
Project Information
Timeline
2025-ongoing
Location
Hood Canal, Puget Sound, WA
Species
Methods
Passive acoustics
Conceptual Framework
Performing Organizations
Principal Investigators
Dawn Grebner & Asila Bergman, NUWC Division, Keyport
Point of Contacts
Bridget Watts, NAVSEA HQ 04E
Data, Reports, & Publications
Technical Reports
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Associated Projects & Blog Posts
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