Do whales hear what we see at the surface? Juliana Houghton*1,2, Marla Holt3, Deborah Giles4, Candice Emmons3,

Brad Hanson3, Jeff Hogan2,5

Key finding: DTAGs on whales show what

they actually hear. When more vessels are around, it is noisier. However speed and size are also important factors, even when vessels are farther away.

* stephj5@uw.edu, julianahoughton.wordpress.com

(1) School of Aquatic & Fishery Sciences, University of Washington, Seattle, WA

(2) Cascadia Research Collective, Olympia, WA (3) NOAA/NMFS/Northwest Fisheries

Science Center, Seattle, WA (4) Geography Graduate Group and

Department of Wildlife, Fish, and Conservation Biology, University of

California, Davis, CA (5) Killer Whale Tales, Seattle, WA

Context: • Marine environment: impacted

by anthropogenic noise (e.g. ship traffic, ecotourism)

• Cetaceans (rely on acoustic environment for life history strategies) are particularly susceptible

• Southern Resident killer whales (SRKW) – ESA listed • Subject to high level of

whale-watching activity • Critical habitat:

San Juan Islands, WA • Vessel interactions &

associated noise are potential stressors

• Missing link: Relationship between vessel traffic and noise levels received by the whale

Methods: • Received noise level (NL in dB re 1 mPa) data

recorded by digital acoustic recording tags (DTAGs) • 1 sec NL segments integrated 1-40 kHz

• Vessel data collected using mobile remote sensing survey equipment package • Precise vessel and whale locations • Vessel attribute data (e.g., ID, size, speed)

• Analytical methods: modeling and statistics to compare vessel data to NL data in 5 min intervals

Vessel Count

Rec

eive

d N

ois

e L

evel

s (d

B)

As the number of vessels increases, received noise levels increase

Noise Level = 100.2 + 5.0*log10Vessel Count

Rec

eive

d N

ois

e L

evel

s (d

B)

Average Vessel Distance

Vessels that are farther away are louder, because they are bigger or faster?

Noise Level = 100.1 + 0.0059*Avg. Vessel Distance

Implications: • Better understand how vessels

contribute to received noise levels • Results can be used to refine existing

vessel regulations (e.g., speed restrictions)

Aid managers in SRKW recovery efforts

Future Work: • Spatial analysis; incorporate bathymetry • Multivariate statistics; include additional

attributes (e.g., orientation, motor type)

Acknowledgments: Glenn VanBlaricom, Robin Baird, Trevor Branch; All pictures were taken under federal research permit, NOAA/NWFSC