Cetacean noise criteria revisited in the light of proposed exposure limits for harbour porpoises

Tougaard, Jakob; Wright, Andrew; Madsen, Peter T.

doi:10.1016/j.marpolbul.2014.10.051

Cited by 113 publications

(122 citation statements)

References 76 publications

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“…For each minutelong recording, the following parameters were extracted: broadband equivalent continuous sound pres sure level (L eq , equal to RMS average over 1 min); sound exposure level cumulated over 1 min (SEL cum ); and the 50th and 5th percentiles (L 50 and L 5 ) for broadband L eq-fast (running RMS average over nonoverlapping 125 ms windows; Tougaard et al 2015). Single-strike SEL (SEL SS ) was estimated from SEL cum and the average number of strikes per minute (n -) as:…”

Section: Noise Analysismentioning

confidence: 99%

Bubble curtains attenuate noise from offshore wind farm construction and reduce temporary habitat loss for harbour porpoises

Dähne¹,

Tougaard²,

Carstensen³

et al. 2017

Mar. Ecol. Prog. Ser.

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Effects of constructing the DanTysk offshore wind farm (German Bight, 80 turbines, 6 m diameter foundations) were studied by passive acoustic monitoring of pile-driving noise and harbour porpoise Phocoena phocoena echolocation. An acoustic deterrence device (seal scarer) was used to protect porpoises from hearing loss and bubble curtains were used to attenuate the pile-driving noise. Porpoise occurrence, quantified by echolocation signals, decreased when the seal scarer was engaged, during pile driving and up to 5 h after pile driving stopped. This effect extended out to 12 km, less than the 18−25 km reported from other pile drivings performed without bubble curtains. The bubble curtains thus effectively reduced the temporary habitat loss and risk of hearing loss. The 2 bubble curtains each attenuated the noise by between 7 and 10 dB, when used separately, and 12 dB when used together. Attenuation was most pronounced above 1 kHz, where the pile-driving noise at larger distances was comparable to or lower than ambient noise. This suggests that noise regulation should be based on frequency-weighted sound levels in addition to broadband levels, to assure that mitigation measures are effective in reducing impact on animals and not only in fulfilling legal requirements. The strong reaction to the seal scarer raises concern that it may surpass the reactions to the pile-driving noise itself, when operating with bubble curtains, and calls for a re-evaluation of the specifications of seal scarer sounds.

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Section: Noise Analysismentioning

confidence: 99%

Bubble curtains attenuate noise from offshore wind farm construction and reduce temporary habitat loss for harbour porpoises

Dähne¹,

Tougaard²,

Carstensen³

et al. 2017

Mar. Ecol. Prog. Ser.

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“…The 2007 limit has since been adopted by many noise producers and managers as an absolute level at which injury impacts to cetaceans occur [(for example, a European Union advisory group used these criteria for their advice on harmful sound levels in EU waters (Tasker et al, 2010;Genesis, 2011)]. The approach used by Southall et al (2007) has been criticized on methodological and statistical grounds, such as inconsistency of weighting functions and problems with pseudo replication that downplay the sensitivity of animals to sound (Tougaard et al, 2015;Wright, 2015). For example, the proposed levels were developed using limited available evidence, where levels at which temporary (TTS) and permanent threshold shift (PTS) and other responses occur in a small number of captive cetaceans from a limited number of species [i.e., common bottlenose dolphins (Tursiops truncatus) and beluga whales (Delphinapterus leucas)], particularly animals kept in the US Navy's marine mammal research facilities.…”

Section: The Received Levels Of Sonar and Beaked Whales Impactsmentioning

confidence: 99%

“…Previous predictions had extrapolated their sensitivity to sound based on results from common bottlenose dolphins (Tursiops truncatus), but experimental results show this appears to have underestimated the sound levels at which impacts (behavioral and TTS) to harbor porpoises might occur (Tougaard et al, 2015). For porpoises, Tougaard et al (2015) found that impacts strongly depend on the frequency of the sound, with avoidance reactions occurring just 40-50 dB above the hearing threshold for a particular frequency, with TTS occurring at about 100 dB above the hearing threshold.…”

Section: Other Cetacean Species Affected By Active Sonarmentioning

confidence: 99%

Impacts of Navy Sonar on Whales and Dolphins: Now beyond a Smoking Gun?

Parsons

2017

Front. Mar. Sci.

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The risks military sonar poses to cetaceans received international attention with a highly-publicized mass stranding of Cuvier's beaked whales (Ziphius cavirostris), Blainville's beaked whales (Mesoplodon densirostris), and northern minke whales (Balaenoptera acutorostrata) in the Bahamas in 2000. This was the first time that the US Government determined a stranding to be the result of mid-frequency active sonar use. Subsequently attention has been drawn to other mass strandings coincident with naval exercises, including events preceding the 2000 mass stranding. The list of species for which mass strandings have been linked to naval exercises has also increased to include other beaked whales, dwarf and pygmy sperm whales (Kogia spp.), pilot whales (Globicephala spp.), several dolphin species (Stenella sp. and Delphinus delphis), and harbor porpoises (Phocoena phocoena). In particular, there have been several mass strandings in the northern Indian Ocean coincident with naval exercises-including one of the largest (200-250 dolphins)-which have received little attention. Changes in beaked whale behavior, including evasive maneuvering, have been recorded at received levels below <100 dB re 1 µPa (rms) and mass stranding may occur at received levels potentially as low as 150-170 dB re 1 µPa. There is strong scientific evidence to suggest that a wide range of whale, dolphin and porpoise species can also be impacted by sound produced during military activities, with significant effects occurring at received levels lower than previously predicted. Although there are many stranding events that have occurred coincident with the presence of naval vessels or exercises, it is important to emphasize that even the absence of strandings in a region does not equate to an absence of deaths, i.e., absence of evidence does not mean evidence of absence. Strandings may be undetected, or be unlikely to be observed because of a lack of search effort or due to coastal topography or characteristics. There may also be "hidden" impacts of sonar and exercises not readily observable (e.g., stress responses). Due to the level of uncertainty related to this issue, ongoing baseline monitoring for cetaceans in exercise areas is important and managers should take a precautionary approach to mitigating impacts and protecting species.

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“…Aerial surveys, GPS tracking of individual animals or passive acoustic monitoring prior to and after plan ned detonations of explosives could be used to test this (for a suggested experimental set-up, see e.g. Dähne et al 2013or Tougaard et al 2015.…”

Section: Avoid and Redistribute Once Exposed?mentioning

confidence: 99%

“…Next, experimentally derived dose-response relationships define the received level at which hearing impairment or behavioural responses are expected to occur (e.g. Southall et al 2007, Lucke et al 2009, Kastelein et al 2012, Tougaard et al 2015. The estimated SEL or SPL maps can then be overlaid with marine mammal distribution estimates, to estimate the number of individuals exposed to sound levels above the behavioural or auditory effect thresholds.…”

Section: Introductionmentioning

confidence: 99%

Harbour porpoise movement strategy affects cumulative number of animals acoustically exposed to underwater explosions

Aarts¹,

Benda‐Beckmann²,

Lücke³

et al. 2016

Mar. Ecol. Prog. Ser.

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Anthropogenic sound in the marine environment can have negative consequences for marine fauna. Since most sound sources are intermittent or continuous, estimating how many individuals are exposed over time remains challenging, as this depends on the animals' mobility. Here we explored how animal movement influences how many, and how often, animals are impacted by sound. In a dedicated study, we estimated how different movement strategies affect the number of individual harbour porpoises Phocoena phocoena receiving temporary or permanent hearing loss due to underwater detonations of recovered explosives (mostly WWII aerial bombs). Geo-statistical distribution models were fitted to data from 4 marine mammal aerial surveys and used to simulate the distribution and movement of porpoises. Based on derived doseresponse thresholds for temporary (TTS) or permanent threshold shifts (PTS), we estimated the number of animals affected in a single year. When individuals were free-roaming, an estimated 1200 and 24 000 unique individuals would suffer PTS and TTS, respectively. This equates to respectively 0.50 and 10% of the estimated North Sea population. In contrast, when porpoises remained in a local area, fewer animals would receive PTS and TTS (1100 [0.47%] and 15 000 [6.5%], respectively), but more individuals would be subjected to repeated exposures. Because most anthropogenic sound-producing activities operate continuously or intermittently, snapshot distribution estimates alone tend to underestimate the number of individuals exposed, particularly for mobile species. Hence, an understanding of animal movement is needed to estimate the impact of underwater sound or other human disturbance.

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Cetacean noise criteria revisited in the light of proposed exposure limits for harbour porpoises

Cited by 113 publications

References 76 publications

Bubble curtains attenuate noise from offshore wind farm construction and reduce temporary habitat loss for harbour porpoises

Bubble curtains attenuate noise from offshore wind farm construction and reduce temporary habitat loss for harbour porpoises

Impacts of Navy Sonar on Whales and Dolphins: Now beyond a Smoking Gun?

Harbour porpoise movement strategy affects cumulative number of animals acoustically exposed to underwater explosions

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