Quiet time for orcas: noise reduction strategies that can assist killer whales in their foraging and communication

Val Veirs, Orcasound Hydrophone Network

Scott Veirs, Beam Reach

Lauren McWhinnie, Patrick O’Hara, & Gregory O’Hagan, NEMES (Noise Exposure to the Marine Environment from Ships)

Salish Sea Ecosytem Conference, April 6, 2018

Orcasound.net

15 years of listening for whales in the (U.S.) Salish Sea

Orcasound hydrophone network organizational members (2018):

    Beam Reach
    Colorado College, Physics & Environmental Science
    Orca Network
    Port Townsend Marine Science Center
    Orca Behavior Institute
    Cetacean Research Technology
    Whale Scout
    Deep Green Wilderness
    Oceans Initiative
    Friends of Lime Kiln Society (FOLKS)
    The Whale Trail
    The Center for Whale Research

Orcasound app and Orcasound Lab

Our study site:

  • in SRKW critical habitat within Haro Strait
  • cabled, calibrated nearshore hydrophones
  • bottom-mounted at depth of ~10 meters
  • 1-2 km from shipping lanes
  • just south of Roche and Snug Harbors
Thank you to everyone who backed our Kickstarter!

Potential impacts of noise on SRKWs

  • PTS/TTS
    1. What explosives were used during the capture era, and previously?
    2. Pile driving:
    3. MFA sonar: (HMS Ottawa, 2012)
    4. Naval detonations: (HMS Ottawa, 2012)
    5. Unidentified urban sounds:
    6. Last Saturday's sperm whale passby:
  • Masking (mostly by vessels, and what we ususally focus upon)
  • Stress (e.g. from lack of food & chronic noise, affecting pregnancies?)
  • Acoustic ecology (e.g. faint sounds of prey, or predators?)
  • Right whale stress fell after 9/11 decreased ship noise in 2001 (Rolland et al., 2012)
  • Anthropogenic noise has reduced right whales’ habitat in Cape Cod Bay by as much as 80 percent -- C.Clark

    • We know: SRKWs respond to noise

    2003: U.S. Navy uses sonar in Haro Strait with SRKW behavior change observed by Center for Whale Research
    2009: SRKWs "speak up" in noise from nearby boats (Holt, Noren, Veirs, Emmons & Veirs)

    Vessel noise can mask both calls & clicks

    Frequencies of vessel noise overlap with SRKW hearing and signals

    Veirs, Veirs, & Wood (2016, PeerJ)

    It's already too loud!

    1. Communication space reduced: 75% for NRKWs (Miller+2006); 94-98% for SRKW by Haro ships (Veirs+2011)
    2. Foraging space reduced 58-89% by Haro ships (Veirs+2011)
    3. See also Holt, 2008 and Lacy+2017.

    We also know:

    1. Ships dominate the Haro Strait soundscape
    2. Ships transit Haro ~20 times/day
    3. Boats elevate mean ambient noise levels ~2dB during summer

    We have many options to "more than mitigate" vessel noise.

    13% of ships radiate 1/2 the fleet's power

    Veirs, Veirs, Williams, Jasny, & Wood (Authorea pre-print, March, 2017)

    Quieting strategies can be combined...

    Veirs, Veirs, Williams, Jasny, & Wood (in rev., 2018; PeerJ pre-print)

    2017 SRKW behavorial study during slow-down trial

    Collaboration with Oceans Initiative

    Theodolite data table

    2017 vessel behavior and noise study

    Collaboration with NEMES

    Continuous hydrophone and AIS data; intermittent images during daytime.

    Receive levels are similar, but boat noise is brief compared to ships

    NEMES camera: source levels of boats

    Video: NEMES images of 20-kt boat with computed range determining source level

    12 hours of ships and boats

    10 Weeks of Haro Strait Noise Statistics

  • Curves are the percentage of time noise levels are less than the x-axis values.
  • Calculated from 10 weeks of data (8/16/2017 - 11/1/2017).

    • A 3dB Volume Demonstration

    A Noisy Ship 3dB Quieter Alternating

    Modeling the passby of a container ship

    Slow the modeled ship from 20 to 11 kts

    Decrease the source level by 3 dB

    Reduce source level by total of 9 dB

    >

    Statistical model of ships and boats

    Comparison between model and the real world

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    Simple model of SRKW active space

    Rcomm is the maximum distance two orca can likely communicate with specified noise

    Slowdown model of communication space

    Convoy model of communication space

    Whale watcher model of communication space

    These actions to help orcas survive can be taken NOW, this spring!

  • Shipping: Schedule large ships into convoys, one inbound & one outbound each day
  • Boats: Set minimum boat-SRKW range to 400 meters & adopt PWWA speed limit of 7 knots within 1 km; or ban boats within 1 km of SRKWs
  • Food supply: Boost number of large chinook salmon (wild and hatchery) for SRKWs in Haro Strait from Salmon Bank to Turn Point by prohibiting all Chinook fishing

    • Future work & acknowledgements

    Thank you!

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