Underwater Vessel Noise in the Haro Strait Lindsay H. Robinson University of Puget Sound Intern with Beam Reach Marine Science and Sustainability School Photo: Lindsay Robinson

Orcas’ Acoustic Environment Orcas may be threatened in U.S. and are endangered in Canada ~ 100 whale watching vessels interact with orcas every summer day in the Haro Strait This doesn’t include tankers, cargo ships and other commercial vessels. Vessel sound may disrupt the orcas’ ability to echolocate and communicate. Orcas responded to Navy ship in May 2002 by grouping together and staying at the surface. How loud are these boats? What is the orientation of sound? What implications might these have on policy? Photo:Guen Jones Study site Haro Strait Friday Harbor Vancouver Island

Procedure and Instruments Cat’s Cradle was used as typical privately owned boat. At 3500 rpm’s, vessel ran transect from me on shore, over fixed hydrophones 0, 1 and 2. I used a laser range finder to measure distances. Sound was measured from approaching and departing vessel. Photo: Val Veirs Me H1 H2 H0 H3

Analysis Methods I used computer sonogram program to find received levels from hydrophone 0. Formula for source level: Source Level= Received Level + Transmission Loss Photo: Patrick Duffy

Source Level Results Min (dB) Max (dB) RL SL Average Source level is 152 dB re 1 meter.

Preliminary Asymmetry Average SL for approaching vessel: 154 dB re 1m Average SL for departing vessel: 156 dB re 1m More data must be analyzed to make any conclusions.

In context Source Levels of the Washington State Ferry, a whale herding device and an average orca call Received Level is an important perspective given different distances. Photo: Val Veirs CatPipeWSFOrca SL Dist.100m1km10km10m RL Assuming cylindrical spreading

Implications This study showed a method for measuring source levels that can be used on other vessels. “Be Whale Wise” guidelines may need to be updated. Vessels departing from whale watching may be inadvertently directing the most noise orcas. Photo : Guen Jones

Conclusions Small private vessels probably aren’t the most disturbing sound in the area (Unless they are really close!) Other boats may prove to be asymmetrical or too loud to be in 100 meter range of orcas. Photo: Lindsay Robinson Photo : Guen Jones

Sonogram frequency spectrum