Changes in the acoustic behavior of gray whales Eschrichtius robustus in response to noise

Dahlheim, Marilyn E.; Castellote, Manuel

doi:10.3354/esr00759

Cited by 22 publications

(10 citation statements)

References 45 publications

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“…The trend for traveling, or switching to travel, more frequently in the presence of motorized boats may be because traveling behavior in Port Orford usually occurs farther offshore relative to Boiler Bay, in deeper waters than where most kayaks, that generally stay closer to shore, occur. Gray whales are acoustically sensitive (Moore and Clarke , Dahlheim and Castellote ); thus, the sound of vessel motors may forewarn individuals of a vessel's arrival and allow for risk assessment and a decision to continue its current behavior or not. Because kayaks are acoustically cryptic, whales may be surprised by an encounter, perceive a risk, and abandon a forage patch (Frid and Dill ).…”

Section: Discussionmentioning

confidence: 99%

Assessment of vessel disturbance to gray whales to inform sustainable ecotourism

Sullivan

Torres

2018

J Wildl Manag

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Ecotourism is a movement that seeks to sustain local communities by uniting conservation, travel, and education. To minimize effects on animal behavior, ecotourism operations must be carefully managed. Local management efforts that can be tailored to the specific area and animals may be more successful than broad‐scale efforts that may be unknown to users of the environment, or inappropriate for the species. A profitable and growing whale‐watch industry exists in Oregon, USA, but prior to this project, no state guidelines existed to protect animals and maintain sustainability of the industry. This project integrated research and outreach regarding gray whale (Eschrichtius robustus) behavioral response to vessels, and translated results into community‐developed vessel operation guidelines. We tracked whales and vessels in summer 2015 using non‐invasive, shore‐based theodolite and photo identification techniques. We monitored 2 sites along the Oregon coast with differing levels of vessel traffic for 4 weeks each. We analyzed tracks of whales using Markov chains to assess behavior state changes relative to location, individual, vessel presence, vessel type, and distance between whale and vessel. We documented significant differences in gray whale activity budgets between control and impact conditions, and between study sites. We did not observe significant differences in individual responses to vessel disturbance. Researchers and stakeholders collaboratively applied these results to create scientifically informed vessel operation guidelines that aim to balance the economic and educational gains of a whale‐watch industry with adequate protection of the exploited whale population to enhance sustainability. © 2018 The Wildlife Society.

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Section: Discussionmentioning

confidence: 99%

Assessment of vessel disturbance to gray whales to inform sustainable ecotourism

Sullivan

Torres

2018

J Wildl Manag

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“…Blue whales have been found to change the interval, types and amplitudes of their calls (McKenna, 2011;Melcón et al, 2012) while male fin whales seem to change their song characteristics . Other baleen whale species such as gray whales (Eschrichtius robustus) also modify calling rates, received levels and percentage of calls (Dahlheim and Castellote, 2016), humpback whales sing shorter versions of their songs (Sousa-Lima et al, 2002) and North Atlantic right whales show short-and long-term changes in their calling behavior in response to increased low-frequency noise (Parks et al, 2007(Parks et al, , 2009(Parks et al, , 2010. However, other studies show that humpback whales respond to increases of noise levels produced by wind but do not compensate for higher levels of noise from vessels (Dunlop, 2016).…”

Section: Discussionmentioning

confidence: 99%

Underwater Ambient Noise in a Baleen Whale Migratory Habitat Off the Azores

et al. 2017

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Assessment of underwater noise is of particular interest given the increase in noise-generating human activities and the potential negative effects on marine mammals which depend on sound for many vital processes. The Azores archipelago is an important migratory and feeding habitat for blue (Balaenoptera musculus), fin (Balaenoptera physalus) and sei whales (Balaenoptera borealis) en route to summering grounds in northern Atlantic waters. High levels of low frequency noise in this area could displace whales or interfere with foraging behavior, impacting energy intake during a critical stage of their annual cycle. In this study, bottom-mounted Ecological Acoustic Recorders were deployed at three Azorean seamounts (Condor, Açores, and Gigante) to measure temporal variations in background noise levels and ship noise in the 18-1,000 Hz frequency band, used by baleen whales to emit and receive sounds. Monthly average noise levels ranged from 90.3 dB re 1 µPa (Açores seamount) to 103.1 dB re 1 µPa (Condor seamount) and local ship noise was present up to 13% of the recording time in Condor. At this location, average contribution of local boat noise to background noise levels is almost 10 dB higher than wind contribution, which might temporally affect detection ranges for baleen whale calls and difficult communication at long ranges. Given the low time percentatge with noise levels above 120 dB re 1 µPa found here (3.3% at Condor), we woud expect limited behavioral responses to ships from baleen whales. Sound pressure levels measured in the Azores are lower than those reported for the Mediterranean basin and the Strait of Gibraltar. However, the currently unknown effects of baleen whale vocalization masking and the increasing presence of boats at the monitored sites underline the need for continuous monitoring to understand any long-term impacts on whales.

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“…In these studies, experimental approaches of bowhead whales by small vessels at high speed showed that whales generally moved away, thereby interrupting foraging, socializing, and playing behavior, while spending less time at the surface. The early 1980s also saw the first and only playback experiment on the response to vessel noise by gray whales (Eschrichtius robustus) in their breeding and nursery habitat off Mexico (Dahlheim, 1987;Dahlheim and Castellote, 2016). Gray whales have a limited repertoire of low-frequency (40-4000 Hz) vocalizations, overlapping with watercraft noise (Dahlheim et al, 1984;Moore and Ljungblad, 1984;Dahlheim and Castellote, 2016;Burnham et al, 2018).…”

Section: Mysticetesmentioning

confidence: 99%

“…The early 1980s also saw the first and only playback experiment on the response to vessel noise by gray whales (Eschrichtius robustus) in their breeding and nursery habitat off Mexico (Dahlheim, 1987;Dahlheim and Castellote, 2016). Gray whales have a limited repertoire of low-frequency (40-4000 Hz) vocalizations, overlapping with watercraft noise (Dahlheim et al, 1984;Moore and Ljungblad, 1984;Dahlheim and Castellote, 2016;Burnham et al, 2018). In the presence of ships and boats, gray whales increased their vocalization rate, and at times of increased outboard engine noise, received levels from gray whales were higher (interpreted as an increase in source levels; Dahlheim, 1987;Dahlheim and Castellote, 2016).…”

Section: Mysticetesmentioning

confidence: 99%

The Effects of Ship Noise on Marine Mammals—A Review

et al. 2019

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The number of marine watercraft is on the rise-from private boats in coastal areas to commercial ships crossing oceans. A concomitant increase in underwater noise has been reported in several regions around the globe. Given the important role sound plays in the life functions of marine mammals, research on the potential effects of vessel noise has grown-in particular since the year 2000. We provide an overview of this literature, showing that studies have been patchy in terms of their coverage of species, habitats, vessel types, and types of impact investigated. The documented effects include behavioral and acoustic responses, auditory masking, and stress. We identify knowledge gaps: There appears a bias to more easily accessible species (i.e., bottlenose dolphins and humpback whales), whereas there is a paucity of literature addressing vessel noise impacts on river dolphins, even though some of these species experience chronic noise from boats. Similarly, little is known about the potential effects of ship noise on pelagic and deep-diving marine mammals, even though ship noise is focused in a downward direction, reaching great depth at little acoustic loss and potentially coupling into sound propagation channels in which sound may transmit over long ranges. We explain the fundamental concepts involved in the generation and propagation of vessel noise and point out common problems with both physics and biology: Recordings of ship noise might be affected by unidentified artifacts, and noise exposure can be both under-and over-estimated by tens of decibel if the local sound propagation conditions are not considered. The lack of anthropogenic (e.g., different vessel types), environmental (e.g., different sea states or presence/absence of prey), and biological (e.g., different demographics) controls is a common problem, as is a lack of understanding what constitutes the 'normal' range of behaviors. Last but not least, the biological significance of observed responses is mostly unknown. Moving forward, standards on study design, data analysis, and reporting are badly needed so that results are comparable (across space and time) and so that data can be synthesized to address the grand unknowns: the role of context and the consequences of chronic exposures.

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Changes in the acoustic behavior of gray whales Eschrichtius robustus in response to noise

Cited by 22 publications

References 45 publications

Assessment of vessel disturbance to gray whales to inform sustainable ecotourism

Assessment of vessel disturbance to gray whales to inform sustainable ecotourism

Underwater Ambient Noise in a Baleen Whale Migratory Habitat Off the Azores

The Effects of Ship Noise on Marine Mammals—A Review

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