Salish Sea vessel research

Latest news:

Ships emit noise at frequencies used by endangered southern resident killer whale.

Introduction

If we think of vessels plying the Salish sea as ships (>~20 meter length) and smaller boats, then many questions can focus in upon each category: 

  • How much noise pollution does each type of ship and boat emit underwater, and does this pollution matter to Salish Sea species?
  • How many ships and boats utilize the critical habitat of the endangered southern resident killer whales (SRKWs), and what are the temporal and spatial distribution of these vessels?
  • How can we use data from the Automatic Identification System and how accurate are theses VHF transmissions of ship identity, speed, etc.?

To address these questions Orcasound member Beam Reach teamed up with the NEMES project at the University of Victoria, which stands for Noise Exposure to the Marine Environment from Ships and is led by Dr. Rosaline Conessa of CORAL (Coastal and Oceans Resources Analysis Laboratory). NEMES researchers Dr. Lauren McWhinnie and Patrick O’Hara developed an automated DSL camera system to assess the distribution and behavior of non-AIS boats and to verify the AIS data that is commonly used to track ships.

The NEMES camera deployed on a tree at Orcasound Lab.

Methods

One of the NEMES camera systems was deployed in August, 2017, at the Orcasound Lab hydrophone node where both calibrated underwater sound pressure levels and AIS data are logged continuously within the summertime habitat of the SRKWs (along the west side of San Juan Island, WA, USA). Strapped to a tree with a view of Haro Strait, the camera captures both the commercial ship traffic going to and from the Port of Vancouver and other ports of the northern Salish Sea, a wide variety of other ships, and boat traffic associated with the nearby ports of Roche and Snug Harbors. Photos are taken during the daytime on a duty cycle designed to allow the speed of boats to be computed (by taking a few images separated by a second or two, and then waiting for ~10 seconds before repeating the cycle).

Visual data analysis has been focused on deriving algorithms for automatic detection and tracking of vessels in the camera images. Val Veirs of Beam Reach has also written and tested software that allows a vessel in the image to be located geographically on the sea surface (e.g. relative to our hydrophone location) by making measurements within the image. Here’s an example of how the acoustic and visual data can be combined:

Results

More than 2.5 million images have been acquired with the NEMES camera at Orcasound (as of fall, 2018). This time lapse video presents an example of NEMES images, in this case from all daytime hours on 9/27/17 — a day when the southern resident killer whales traveled through our study area, along with a wide variety of boats and ships.

A day in killer whale habitat on the west side of San Juan Island (9/27/17).

Invited presentation at the 2018 Acoustical Society of America meeting

Orcasound lab: A soundscape analysis case study in killer whale habitat with implications for coastal ocean observatories

Cumulative distributions of annual broadband noise level within critical habitat of southern resident killer whales (Orcasound Lab in Haro Strait). The black curve is received level (10-22,050 Hz); blue has ships removed; red has both ships and boats removed. Existing and proposed noise thresholds are indicated by black lines, dots, and arrows… and we define the “urban ambient” level at which local anthropogenic noise begins to influence natural ambient conditions. At Orcasound Lab noise levels remain below this threshold (of 99 dB) about 20% of the time.
The peak broadband noise level received from passing boats (in red) and ships (in black) versus the time period during which they exceeded an “urban ambient” threshold (99 dB re 1 microPa, 10-22,050 Hz). The green zone represents the range of broadband noise levels (105-110 dB re 1 microPa, 1-40 kHz) received on DTAGS deployed on southern resident killer whales in the presence of the whale watching fleet.

More project photos:

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