Oceans of noise - Whale and Dolphin Conservation Society

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However, despite the reported low auditory sensitivity of beluga whales to low frequencies(Awbrey et al. 1988; Johnson et al. 1989) they were able to detect, and reacted to, low frequencynoises at distances of up to 85km. The beluga whale reactions occurred at a distance much greaterthan would have been predicted by mathematical sound propagation models, using data onauditory thresholds (the minimum sound level required before an animal can hear a sound of acertain frequency). Acoustic sensitivity data gathered from captive animals predicted that belugawhales would not have been able to hear the approach of shipping vessels any greater than 20kmaway (assuming a threshold of 104 dB re 1µPa at 1 kHz; Johnson et al. 1989). It can not becompletely ruled out, however, that the belugas were reacting to higher harmonics of thegenerally low frequency shipping noise or that modelled propagation conditions did not representactual conditions.Most auditory sensitivity experiments are conducted on cetaceans in captivity. The tanks in whichcaptive cetaceans are kept frequently have a high level of ambient noise from human activitiesnearby, machinery associated with the tanks (filters, pumps and chillers) and the nature of thetanks often causes cetacean vocalisations and echolocation clicks to reflect multiple times, furtherensonifying the tanks. It is highly likely that animals kept in such environments may suffer somehearing impairment through living in a high noise environment. Doubt, therefore, should beplaced on studies of cetacean hearing capabilities produced in captive environments, and freerangingcetaceans are likely to be more sensitive to sounds, at lower levels, than portrayed in thecited studies above.In addition, low frequency sounds may be detected by some mechanism other than conventionalhearing. This has been suggested to be the case for bottlenose dolphins (Turl 1993) when researchshowed that bottlenose dolphins could detect frequencies of only 50-150Hz. The skin of toothedwhales is extremely sensitive (Palmer & Weddell 1964; Yablokov et al. 1974) and sensitive tovibrations (Ridgeway 1986) or small pressure changes in the area surrounding the eyes, blowholeand head region (Kolchin and Bel’Kovich 1973; Bryden and Molyneux 1986). These authorssuggest that dolphin skin receptors can detect changes in hydrodynamic and hydrostatic pressure,including low frequency sound.Most studies investigating the acoustic sensitivities of cetaceans are, as mentioned above,conducted on captive animals. As mysticetes are too large to keep in captivity, experiments havelargely not been conducted to determine to auditory sensitivity of baleen whales. Ridgeway andCarder (2001), however, attempted to determine the auditory sensitivity of a stranded andrehabilitated gray whale calf. This study suggested that the calf was most sensitive to frequenciesof 3 kHz, 6 kHz and 9kHz although the authors had difficulties in obtaining definitive resultsfrom the experiment (Ridgeway and Carder 2001). However, behavioural reactions from graywhales in the wild to differing frequencies, suggest that they are most sensitive to frequencies ofbetween 0.8 and 1.5 kHz (Dalheim and Ljungblad 1990).4.6. Cetacean vocalisationsThe vocalisations of cetaceans also give us an idea of their hearing sensitivities, i.e. we expectthat they will have very sensitive hearing for sound frequencies that are the same as their socialcalls and echolocation clicks. Cetacean vocalisations extend over a wide range of frequenciesfrom the ultrasonic pulses of porpoises (130-150 kHz) (see Table 4.1) to the low frequency moansof blue whales (10-15 Hz) (Table 4.2).49
Table 4.1. Summary of sound frequencies used by selected toothed whales (odontocetes) forcommunication and echolocation.SpeciesDelphinapterus leucasDelphinus delphisGrampus griseusGlobicephala melasWhistlesPulsed tonesMisc.vocalisationsEcholocationclicksWhistlesChirpsBarksClicksWhistlesRaspsEcholocationclicksWhistlesClicksEcholocationclicksFrequencyrange (kHz)0.26-200.4-120.5-1640-60, 100-1202-188-14
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Page 8 and 9: In the US, the deployment of Low Fr
Page 10 and 11: its propagation beyond those declar
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Page 14 and 15: Box 1. Characteristics of sound / l
Page 16 and 17: Sound speed (c)The speed (c) of a w
Page 18 and 19: Box 2. The effects of temperature,
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Page 22 and 23: i.e. Equal pressure measurements di
Page 24 and 25: Spherical or Geometrical spreading
Page 28 and 29: 5.0 145Tug pulling loaded barge 1.0
Page 30 and 31: The source used during 3-D surveys
Page 32 and 33: Machinery noisePropulsion machinery
Page 34 and 35: Man-made islands /caissonsFixed pla
Page 36 and 37: 12 3245Drill bit6Figure 3.4. Sound
Page 38 and 39: Transientnoise sourcesAircraftHelic
Page 40 and 41: Results from the aerial surveys con
Page 42 and 43: haemorrhaging in the inner ears and
Page 44 and 45: However they also noted that whales
Page 46 and 47: 4. The Use of Sound by CetaceansChr
Page 48 and 49: seems logical, therefore, that if t
Page 52 and 53: Kamminga and Wiersma 1981;Akamatsu
Page 54 and 55: SongSocial callsShrieksSlaps0.03-80
Page 56 and 57: anthropogenic factors that make the
Page 58 and 59: 5.3 Longer-term impactsNoise is cle
Page 60 and 61: 5.4 Indirect impactsThe above impac
Page 62 and 63: decompression sickness (DCS) as see
Page 64 and 65: 6. Examples of regional and nationa
Page 66 and 67: 6.3 ASCOBANS and ACCOBAMSTwo region
Page 68 and 69: implications and the discussion sho
Page 70 and 71: 7.1. Consideration of Voluntary vs.
Page 72 and 73: acoustic measurements have been mad
Page 74 and 75: 7.6. Methods of protectionComplianc
Page 76 and 77: 7.6.1 Monitoring7.6.1.1 Visual, aco
Page 78 and 79: Delory et al. (2002) use Ambient No
Page 80 and 81: 8. ReferencesAburto, A., Rountry, D
Page 82 and 83: Caldwell, M.C., Caldwell, D.K., and
Page 84 and 85: Engas, A., Lokkeborg, S., Ona, E. a
Page 86 and 87: IWC 2002b. Report of the Scientific
Page 88 and 89: McCauley, R.D. 1994. Seismic Survey
Page 90 and 91: Potter, J. and Delory, E. 2001. Noi
Page 92 and 93: Smolker, R.A., Mann, J. and Smuts,
Page 94 and 95: Watkins, W.A. 1981b. The activities
Page 96 and 97: ANNEX 1The Application of Marine Po
Page 98 and 99: an important factor. 13 The judgeme
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in the preparatory work of the LOSC
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practice by the UNEP Governing Coun
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protection and preservation of the
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than international rules, standards
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Four of the twelve regional seas tr
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seismic operations in the Protocol
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ConclusionAt the global level, only
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Art 209 LOSC focuses on both standa
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No State Party may impose condition
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coastal States”. This formulation
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If the IMO makes this determination
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estrictions to vessels operating in
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In the EEZ, in comparison to the te
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Appendix A - Some international ins
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Convention for the Protection of th
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Available at:http://www.unep.ch/sea
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BucharestConventionArticle XIPollut
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environment1. The Contracting Parti
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- that under Article III.8.c) of AC
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e) no sudden or repeated change in
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Ref: Nowacek et al. 2001.Location:
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Location: Arctic• Vocal behaviour
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• Vaquita surfacing duration and
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• 6% of small delphinids (n=264;
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Species type: Boto, Inia geoffrensi
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• Humpback whales appeared tolera
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• Behaviour interpreted as aggres
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• There was no evidence of minke
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• Northern right whales may be ap
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• Migrating gray whales disturbed
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to Ensenada De La Paz, Mexico. Aqua
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distribution of humpback whales, Me
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Richardson, C.R. Greene, C.I. Malme
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Zhou, K., Pilleri, G. and Li, Y. 19
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6. surveys for Cuvier’s beaked wh
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Oceans of noise - Whale and Dolphin Conservation Society

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