(Color online) (a) The Salish Sea with the study area highlighted. (b) Admiralty Inlet bathymetry and deployment site (closed circle) with extent of ship tracking (white outline). (c). Ship tracks from January 1 to January 15, 2011. Gray lines are local ferry traffic and black lines are all other vessel traffic.
(Color online) Ship traffic density map plotted on a 100 m × 100 m horizontal grid. Each subplot represents an area with the dimensions of 28 km by 40 km. In the passenger vessel density subplot, grid points located under the ferry traffic route are saturated to avoid obscuring the traffic patterns of other passenger vessels such as high-speed ferries.
Sample acoustic data from February 12, 2011. The time series are constructed from 10 s recordings every minute. (a) Spectrogram showing regular increases in energy content over all frequencies due to vessel traffic. (b) Time series of one-third octave band SPLs with center frequencies from 16 Hz to 25 kHz. (c) Time series of broadband SPLs (0.02–30 kHz).
(Color online) Cumulative probability distribution function of unweighted broadband SPLs (0.02–30 kHz) and M-weighted cumulative probability distribution functions for pinnipeds in water (Mpw) and low- (Mlf), mid- (Mmf), and high-frequency (Mhf) cetacean marine mammal functional hearing groups.
(Color online) Hourly (a), daily (b), and monthly (c) average broadband (0.02–30 kHz) and M-weighted SPLs. The box plots show the range for the 25%–75% thresholds and the whiskers show the range for the 5%–95% thresholds for broadband SPLs. The mean, minimum, and maximum sample sizes () are included for the statistics in each subplot. February and August sample sizes were significantly below the mean due to extended AIS receiver outages and data gaps from bottom-package recovery/redeployment.
(Color online) (a) Percentile calculations of pressure spectral density for unweighted received levels. (b) Percentiles for unweighted received levels in one-third octave band SPLs. The received broadband SPLs associated with the percentage thresholds are 107.3 dB (5%), 113.4 dB (25%), 119.2 dB (50%), 124.5 dB (75%), and 132.3 dB (95%).
(Color online) (a) Acoustic spectra for a cargo ship at 1.5 km, the local ferry at 1.0 km, and a tug at 1.2 km, and the fifth percentile spectrum. (b) One-third octave band SPLs for the respective spectra in (a).
Cumulative probability distributions of ambient noise (0.02–30 kHz) in the study area for measurements (all ambient noise sources) and the model for vessel noise. The gray envelope of modeled noise represents predicted received levels using transmission loss coefficients from 15 to 16.
(Color online) (a) Site map and profile locations used for the range dependent PE model. A typical ship track for southbound traffic is included (white line). (b)–(f). Transmission losses modeled at 50, 100, and 250 Hz and a comparison with the simplified model. For P1, the missing points are associated parts of the profile where the receiver depth of 57 m was below the water–sediment interface. The transmission loss is plotted every 100 m to reduce the clutter associated with the modal interference patterns. Each transmission loss plot ends at the location of the hydrophone deployment.
Received levels (0.02–30 kHz) from local ferry traffic versus the distance between the ferry and the hydrophone.
Merged frequency bands.
Ship traffic summary, including the total number of vessels, the total number of vessel hours spent in the study area, average speed over ground, and average length overall by vessel class and type. SOG and LOA values include the standard deviations.
Vessel name, type, LOA, SOG, and CPA for events highlighted in Fig. 3.
Estimated source levels (0.02–30 kHz) based on received levels (0.02–30 kHz) for selected ships.
Vessel noise budget calculated by Eq. (3).
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