Quiet Sound’s Voluntary Ship Slowdown Reduces Underwater Noise Reaching Killer Whales

The arrival of endangered Southern Resident killer whales in Admiralty Inlet and Puget Sound in September will trigger a voluntary slowdown for large commercial vessels.ast year, the slowdown reduced by half the underwater noise reaching the whales.

The Voluntary Large Commercial Vessel Slowdown is an initiative of Quiet Sound, a program of Washington Maritime Blue. It's driven by a leadership committee composed of ports, agencies, tribes, and other groups collaborating to reduce threats from large commercial vessels to killer whales and other marine mammals. You can help by reporting whale sightings. The Whale Report Alert System will relay the sightings to mariners so they know when and where to watch for the marine mammals.

NOAA Fisheries named Quiet Sound a Partner in the Spotlight in 2023 after they successfully launched the first trial slowdown period in the fall of 2022. "The collaboration with our partners and industry is what makes this work," said Gretchen Hanshew, acting branch chief for the Protected Resources Division in NOAA Fisheries' Seattle office. "Quiet Sound saw measurable improvements last year, so I am optimistic that we may see even larger noise reductions this year. We know that makes a meaningful difference for the whales by reducing how much energy they have to spend each day to survive."

Quiet Sound will initiate the voluntary slowdown just after midnight on the day after SRKW have entered the area, no earlier than September 3. They typically arrive each fall as they follow the return of salmon and steelhead to area rivers. The slowdown will continue through January 12. Commercial vessels transiting the area are encouraged to reduce their speed when it is safe and operationally feasible to do so. Large cruise ships and container ships are asked to reduce their speeds to 14.5 knots, for instance.

Fishing and recreational vessels are not asked to slow down.

"A voluntary slowdown achieves great results in quieting the waters for whales thanks to strong cooperation from the maritime sector," says Rachel Aronson, Director of Quiet Sound. "We thank the Puget Sound pilots, professional sailors, maritime shippers, the cruise industry and the tug sector for all they do on the water to help Washington's blue economy and whales thrive together."

Research has shown that the noise from ship traffic increases at higher speeds, so slowing down reduces the amount of noise produced. More than 70 percent of the roughly 800 ships that transited the area during last year's slowdown reduced their speed. That reduced sound levels reaching whales by about half, including at the frequencies the whales use to communicate and track prey.

"The results from last year demonstrate that mariners took the slowdown seriously and most slowed down substantially, and that had just the benefit we were hoping to see-less noise underwater," Hanshew said. "It's great to see this kind of collaboration make such an important contribution to our recovery goals for Southern Resident killer whales."

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