Map of Saguenay Fjord mouth showing (a) the bathymetry of the study area, (b) the locations of beluga groups from daytime reticule binocular observations from Pointe Noire during the study period, (c) theSaguenay ferries main paths as described by Chion et al. (2010) from AIS data analysis, and (d) the distribution of monitored whale-watching boats in summer 2009 from Parks Canada vessel track observations.
(Color online) Percentiles of the cdf of the estimated SSL of the whale-watching fleet (continuous lines) and ship SSL references (from Mitson, 1995; NRC, 2003) (dotted lines). 1: supertanker, 2: large tanker, 3: tanker, 4: merchant ship, 5: fishing vessel, 6: ICES recommendation for fisheries research vessels.
(Color online) (a) Median SSL per vessel category and (b) their corresponding 2-s.d. envelope.
(Color online) ΔSLwb difference as function of speed increment (Δv) between ∼10–15 kn to 26 kn per vessel category, separately for the (a) 0.01–1 kHz bandwidth, (b) the 1–20 kHz bandwidth from hydrophones 3 and 4, and (c) comparison of the 0.01–20 kHz bandwidth from hydrophone no. 4 with Erbe (2002).
(Color online) Percentiles of the cdf of measured noise PSD over the [10 Hz–10 kHz] band during the recording period; the 10th percentile corresponds to the estimated natural ambient levels. The slopes of the median, 99th and 10th percentiles are extended to the [10–100 kHz] band from a linear fit to [5–10 kHz] frequencies. Overimposed are Wenz’s reference curves for heavy traffic < 3 kHz and for 40 kn wind >200 Hz (arrow pointed bold dotted lines), and beluga audible levels (shaded area) from the 1-s.d. lower bound of the composite audiogram envelope of Finneran et al. (2005), extended to 100 Hz with a slope of −30 dB per decade from Erbe (2002).
(Color online) Probability that daytime noise differs from nighttime noise by the number of dB indicated by the ordinate axis, for frequencies from 10 to 10 000 Hz. Median difference with 1-dB resolution (dashed line); mean difference (continuous bold line).
(Color online) Mean broadband SPL over the diel cycle for the low- (dotted line) and high-frequency (triangle line) bands separately and pooled (thin upper line) during the recording period and the daytime traffic statistics from Chion et al. (2010) (middle line).
(Color online) High-resolution SPLwb [1–20 kHz] for 7 June 2010 (dots) with its smoothed low-pass version (Butterworth filter, order 4, cutoff frequency = 1/3600 Hz) (middle bold line), the ±12 dB estimated magnitude of the fast oscillations around the low-pass series due to ferry transits (thin lines) and the monthly average (lower bold line).
(Color online) SPLwb [1–20 kHz] diel series by source: natural floor level (dotted line), SPLwb with the addition ferry hourly mean level (triangle line), and total SPLwb including the whale-watching fleet (upper line).
(Color online) Saguenay Fjord mouth noise excess and RRF relative to natural conditions (a) cdf quartiles of noise level increments relative to natural ambient noise, ΔNL, as a function of acoustic frequency; these ΔNL are exceeded 75% of the time for the first quartile, 50% for the median, and 25% of the time for the third quartile, and (b) the corresponding range reduction factor, i.e., the percentage of time the range is below the given ratios relative to natural conditions.
(Color online) (a) Cdf of measured noise PSD as in Fig. 5 but for twelfth-octave bands, (b) level-frequency areas of masked signals corresponding to the 50th or 99th percentile of the measured noise cdf, based on the Fletcher’s equal-power tonal masking model and beluga CR from Johnson et al. (1989). Signals with twelfth-octave levels smaller than the curves would be masked assuming no behavioral or auditory compensation. Beluga audible area (shaded background) as in Fig. 5.
Saguenay ferry shipping and whale-watching fleet diel schedule. Measured broadband SPL[1–20 kHz] (in dB re 1 μPa) and estimated natural ambient and ferry noise levels averaged over 1 h.
Characteristics of the whale-watching fleet vessel types used for source level assessment at two sailing speeds.
SLwb median and s.d. per vessel class.
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