John P. Ryan –
Monterey Bay Aquarium Research Institute
7700 Sandholdt Road
Moss Landing, CA 95039

John E. Joseph –
Tetyana Margolina –
Department of Oceanography
Naval Postgraduate School
Monterey, CA 93943

Leila T. Hatch –
Stellwagen Bank National Marine Sanctuary, NOS-NOAA
175 Edward Foster Road
Scituate, MA 02066

Andrew DeVogelaere –
Monterey Bay National Marine Sanctuary, NOS-NOAA
99 Pacific Street, Bldg. 455A
Monterey, CA  93940

Lindsey E. Peavey Reeves –
NOAA Office of National Marine Sanctuaries
National Marine Sanctuary Foundation
Silver Spring, MD 20910
Channel Islands National Marine Sanctuary
University of California, Santa Barbara
Santa Barbara, CA  93106

Brandon L. Southall –
Southall Environmental Associates, Inc.
9099 Soquel Drive, Suite 8
Aptos, CA 95003

Simone Baumann-Pickering –
Scripps Institution of Oceanography, UC San Diego
Ritter Hall 200F
La Jolla, CA 92093

Alison K. Stimpert –
Moss Landing Marine Laboratories
Moss Landing, CA, 95039

Popular version of paper 4pAO1
Presented Thursday afternoon, December 10, 2020
179th ASA Meeting, Acoustics Virtually Everywhere

Imagine speaking with only your voice – no technology – and being heard by someone over a hundred kilometers away.  Because sound travels much more powerfully in water than it does in air, great whales can communicate over such vast distances in the ocean.

Whales and other oceanic animals produce and perceive sound for essential life activities – communicating, finding food, navigating, reproducing, and surviving.  This means that we can learn a lot about their underwater lives by recording and analyzing the sounds they produce and hear.  It also means that the noise we introduce into the ocean can cause harm.  Protecting oceanic species and their habitats requires an understanding of the detrimental impacts of our noise and strategies to mitigate these impacts.

There are many sources of anthropogenic noise in the ocean, but the most pervasive and persistent source is that of vessels, notably large commercial ships engaged in global trade.  This worldwide bustling is among the many human activities influenced by the COVID-19 pandemic.  Using sound recordings from the deep sea and information about vessel traffic, we examined oceanic quieting caused by reduced shipping traffic within Monterey Bay National Marine Sanctuary (Figure 1) during this ongoing pandemic.

Oceanic Quieting

Figure 1.  Study context.  Shaded regions represent Monterey Bay National Marine Sanctuary.  The black circle shows the location of a deep-sea (890 m) observatory connected to shore by a cable, through which we recorded sound.  Red and blue lines define nearby shipping lanes.

Our first question was whether the quieting we measured during 2020 could be explained by reduced traffic of large vessels.  We quantified vessel traffic using two independent data sources: (1) economic data representing vessel activity across all California ports, and (2) location data sent from vessels to shore continuously as they transit between ports.  Both of these data sources yielded the same answer: quieting within the sanctuary during January–June 2020 was caused by reduced shipping traffic.  Further, a rebound in noise levels during July 2020 was associated with an increase in vessel traffic.

Our second question was how much quieter 2020 was compared to previous years.  Using the previous two years as a baseline, we found that 2020 was quieter than both previous years during the months of February through June.  Low-frequency noise levels during June 2020, the quietest month having the least shipping activity, were reduced by nearly half compared to June of the previous two years.  For baleen whales that use low-frequency sound to communicate, potential consequences of this quieting include less time exposed to noise-induced interference and stress, and greater distance over which communication can occur.

The effects of this pandemic on oceanic noise will differ from place to place, depending on proximity to hubs of maritime activity, the nature of noise produced by each activity, and the degree and timing of pandemic influence.  These changes are being examined across U.S. National Marine Sanctuaries and all around the world.  The COVID-19 pandemic resulted in an unexpected global experiment in oceanic noise, one that could reveal better ways to care for ocean health and its powerful support of humanity.

Study overview

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