Whale-watch vessel noise levels with applications to whale-watching guidelines and conservation

Disturbance from whale-watching can cause significant behavioural changes with fitness consequences for targeted whale populations. However, the sensory stimuli triggering these responses are unknown, preventing effective mitigation. Here, we test the hypothesis that vessel noise level is a driver of disturbance, using humpback whales (Megaptera novaeangliae) as a model species. We conducted controlled exposure experiments (n = 42) on resting mother-calf pairs on a resting ground off Australia, by simulating whale-watch scenarios with a research vessel (range 100 m, speed 1.5 knts) playing back vessel noise at control/low (124/148 dB), medium (160 dB) or high (172 dB) low frequency-weighted source levels (re 1 μPa RMS@1 m). Compared to control/low treatments, during high noise playbacks the mother’s proportion of time resting decreased by 30%, respiration rate doubled and swim speed increased by 37%. We therefore conclude that vessel noise is an adequate driver of behavioural disturbance in whales and that regulations to mitigate the impact of whale-watching should include noise emission standards.

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NOISE LEVELS AND MASKING POTENTIAL OF SMALL WHALE-WATCHING AND RESEARCH VESSELS AROUND TWO DELPHINID SPECIES

Bioacoustics ◽

10.1080/09524622.2008.9753803 ◽

2008 ◽

Vol 17 (1-3) ◽

pp. 166-168 ◽

Cited By ~ 4

Author(s):

FRANTS H. JENSEN ◽

MAGNUS WAHLBERG ◽

LARS BEJDER ◽

PETER T. MADSEN

Keyword(s):

Noise Levels ◽

Whale Watching

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Variability in Anthropogenic Underwater Noise Due to Bathymetry and Sound Speed Characteristics

Journal of Marine Science and Engineering ◽

10.3390/jmse9101047 ◽

2021 ◽

Vol 9 (10) ◽

pp. 1047

Author(s):

Svein Vagle ◽

Rianna E. Burnham ◽

Caitlin O’Neill ◽

Harald Yurk

Keyword(s):

Water Column ◽

Transmission Loss ◽

Spatiotemporal Variability ◽

Mitigation Measures ◽

Seasonal Temperature ◽

Noise Levels ◽

Noise Mitigation ◽

Cetacean Species ◽

Near Surface ◽

Vessel Noise

Oceanic acoustic environments are dynamic, shaped by the spatiotemporal variability in transmission losses and sound propagation pathways of natural and human-derived noise sources. Here we used recordings of an experimental noise source combined with transmission loss modeling to investigate changes in the received levels of vessel noise over space and time as a result of natural water column variability. Recordings were made in the Juan de Fuca Strait, on the west coast of Vancouver Island, a biologically productive coastal region that hosts several cetacean species. Significant variability in noise levels was observed due to changing water masses, tied to seasonal temperature variation and, on a finer scale, tidal movements. Comparisons of interpreted received noise levels through the water column indicated that vessel noise recorded by bottom-stationed monitoring devices might not accurately represent those received by whales in near-surface waters. Vertical and temporal differences of 3–5 dB were commonly observed in both the recorded and modeled data. This has implications in estimating the success of noise mitigation measures, and our understanding of the change in sound fields experienced by target species for conservation.

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Understanding Effects of Whale-Watching Vessel Noise on Humpback Whale Song in the North Pacific Coast of Colombia With Propagation Models of Masking and Acoustic Data Observations

Frontiers in Marine Science ◽

10.3389/fmars.2021.623724 ◽

2021 ◽

Vol 8 ◽

Author(s):

Maria Paula Rey-Baquero ◽

Laura Valentina Huertas-Amaya ◽

Kerri D. Seger ◽

Natalia Botero-Acosta ◽

Andrea Luna-Acosta ◽

...

Keyword(s):

Marine Mammals ◽

Large Scale ◽

Humpback Whale ◽

Propagation Model ◽

Anthropogenic Noise ◽

Whale Watching ◽

Southern Limit ◽

Acoustic Data ◽

Communication Space ◽

Vessel Noise

Soundscapes with minimal anthropogenic noise sources are key for the survival and effective communication of marine mammals. The Gulf of Tribugá is part of the breeding ground for humpback whale Stock G. Currently, no large-scale infrastructure exists on the Gulf's coastline, making it an area with high biodiversity and little anthropogenic noise. Whale-watching is one of the few human activities that contributes to the soundscape. By Morro Mico, on the southern limit of the Utría Natural National Park, an Ecological Acoustic Recorder (EAR, Oceanwide Science Institute) was deployed in the Gulf to record samples of acoustic activity from October to November 2018. It recorded for 10-min intervals with 20-min lapses for a duty cycle of 33.3%. One of the common peak frequencies of humpback whale song units from these recordings was used as input to an acoustic propagation model using the parabolic equation to simulate the communication space of a humpback whale when zero, one, and two boats are present. GPS positions of theodolite data from various whale watching scenarios in the Gulf were used to inform the models. Model results indicate that humpback whale song communication space could be reduced by as much as 63% in the presence of even one whale-watching boat. The boats traveling through the Gulf are the same as those used in whale-watching, and their engine noise while passing Morro Mico coincided with song structural and temporal changes observed in the acoustic data. Combining in situ data with acoustic models can advance the understanding of the spatio-temporal acoustic reactions of whales when their vocalizations are masked by boat noise. This project serves as an approximation of how humpback whale Stock G may respond to whale-watching vessel noise in the Gulf of Tribugá.

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Damage Risk: An Evaluation of the Effects of Exposure to 85 versus 90 dBA of Noise

Journal of Speech and Hearing Research ◽

10.1044/jshr.1902.216 ◽

1976 ◽

Vol 19 (2) ◽

pp. 216-224 ◽

Cited By ~ 3

Author(s):

James T. Yates ◽

Jerry D. Ramsey ◽

Jay W. Holland

Keyword(s):

White Noise ◽

Statistical Difference ◽

Noise Exposure ◽

Threshold Shift ◽

Temporary Threshold Shift ◽

Noise Levels ◽

Potential Damage ◽

Full Day ◽

Damage Risk

The purpose of this study was to compare the damage risk of 85 and 90 dBA of white noise for equivalent full-day exposures. The damage risk of the two noise levels was determined by comparing the temporary threshold shift (TTS) of 12 subjects exposed to either 85 or 90 dBA of white noise for equivalent half- and full-day exposures. TTS was determined by comparing the pre- and postexposure binaural audiograms of each subject at 1, 2, 3, 4, 6, and 8 kHz. It was concluded that the potential damage risk, that is, hazardous effect, of 90 dBA is greater than 85 dBA of noise for equivalent full-day exposures. The statistical difference between the overall effects of equivalent exposures to 85 dBA as compared to 90 dBA of noise could not be traced to any one frequency. The damage risk of a full-day exposure to 85 dBA is equivalent to that of a half-day exposure to 90 dBA of noise. Within the limits of this study, TTS t was as effective as TTS 2 for estimating the damage risk of noise exposure.

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