For many animals that live beneath the waves the
ability to create and hear natural sounds is vital to
their existence. Numerous species, from whales to
dolphins to shrimps, use sound to communicate,
navigate, and feed. Indeed, because the underwater
world can be severely limiting to other senses such
as vision, for many marine species sound is the
primary means to communicate and learn about
their environment.1 Humans don’t hear well beneath
the waves because our ear canals fill with water,
preventing our eardrums from vibrating,2 but marine
species sense sound in different ways; in many
cases, they literally hear sound in their bones.3
The sounds they make, the reasons they make them,
and the manner in which they do so, are as various
as ocean life itself. Pistol shrimps snap their giant
claws with such force that the action produces an
air bubble of sound powerful enough to stun the
shrimps’ prey.4 During courtship, at times of stress,
or as a territorial display, fish may generate noises
—described variously as grunts, groans, thuds, and
barks—by grinding their teeth or tightening and
loosening muscles to vibrate their swim bladders.5
Leopard seals in the waters surrounding the Antarctic
have been reported to emit ultrasonic sounds when
chasing prey, while the haunting sounds made
by Weddell seals evoke the sound effects of old
science-fiction movies and have been likened to
techno music and a Pink Floyd concert.6 At the
other end of the global ocean, walruses produce a
repertoire of vocalizations that have been described
as sounding like “a circus, a construction site,
a Road Runner cartoon…They whistle, beep, rasp,
strum, bark, and knock. They make bell tones,
jackhammer drills, train track clatters, and the
rubber-band boing of Wile E. Coyote being bonked
on the head.”7
To listen through a hydrophone, or underwater
microphone, to a pod of orcas on a hunt is to marvel
at the social interplay and cooperation conveyed
through their squeaks and clicks. Orca researcher
Paul Spong has noted that, “Living in the ocean,
these social mammals use sound to navigate,
find their food, and stay in touch with each other.
It’s a very complex and varied world of sound.”8
But the deepest, loudest, and farthest-carrying
noises in the underwater animal kingdom are the
ones that are made by the great whales.
The Songs of the Whales
The most famous ocean sounds of all are the
‘songs’ of humpback whales, long known to
mariners but first truly examined by Roger and
Katherine Payne and Scott McVay in 1967.
9 It
was the Paynes and McVay who discovered that
the strange, haunting moans of humpbacks could
truly be called songs, in that they involve repeated
sequences called “themes,” each generally between
15 and 30 minutes long, that are, in Roger Payne’s
words, “strung together without pauses so that a
long singing session is an exuberant, uninterrupted
river of sound that can flow for twenty-four hours or
longer.” Katherine Payne made a further discovery:
that the songs change over time; at any given
moment, all the singing humpback whales in a
particular region sing the same song, but they tinker
with and alter that song, a piece at a time, until,
over the course of several years, the song they all
sing has evolved considerably. Only males sing; the
songs are delivered with such power that, in Roger
Payne’s telling, “When you swim up next to a singing
whale through the cool, blue water, the song is so
loud, so thundering in your chest and head, you feel
as if someone is pressing you to a wall with their
open palms, shaking you until your teeth rattle.”10
Although humpback vocalizations are the most
celebrated and melodious of those made by whales,
they are not the only ones.
Right whales produce a fantastic variety of calls for
different social situations, from low rumblings like
those from a speaker with the bass turned up, to
sounds like a gunshot or a firework disappearing
into the sky, and ‘screams’ that could be mistaken,
out of context, for the cries of an elephant.
Different vocalizations perform different functions.
Short “upcalls” for example, which are made most
frequently, seem to be greetings, a way for each
whale to announce its presence to others in
the area; gunshot sounds, produced by males,
are most likely reproductive in nature, and the
elephant-like screams are made when right whales
gather in groups at the surface.11
The long, rumbling moans emitted by blue whales
propagate immense distances across the ocean and
have been picked up by hydrophones from distances
of 700 miles. It had long been thought that blues
and fins were largely solitary animals; now biologists
believe they organize themselves in long-distance
“herds,” not in each other’s sight but in constant
contact across ocean basins because of their
powerful vocalizations.12
There are many other natural noises beneath the
waves. The crashing of waves on the shore, a
familiar sound to beachcombers, also reverberates
beneath the surface. Increased wind strength can
affect wave action at the sea’s surface, raising
background levels of sound. In Polar regions, sea ice
dynamics
—including ice formation and deformation,
pressure ridging, and cracking
—increase ambient
noise levels over a broad range of frequencies.
In the Antarctic, acoustic signals from icebergs
include harmonically rich tremors that can last
from hours to days.13
Such background sounds, no matter how loud or how
well propagated, have been present in the global
ocean for millions of years and have always been a
part of whales’ existence. Over the past century or so
however, new sounds have entered the ocean realm.
Anthropogenic Noise Interferes and Overwhelms
As the ocean has become industrialized, new noises
have entered the undersea world, in many cases
drowning out not only these background sounds
but also causing physical harm to whales and other
marine life. Explosives, pile-drivers, seismic airguns,
and sonar produce acute noise that can induce
stress, disrupt vital behavior, and even cause
physical injury in species as diverse as fish, squid
and cuttlefish, and marine mammals.
For example, studies have found damage to the
swim bladders or inner ear sensory hair cells
of some fish as a result of being exposed to
explosions, pile driving, and seismic blasts.
Catches of fish such as cod, haddock, and rockfish
have declined significantly within large areas around
seismic air gun surveys; cod and herring have been
observed swimming away from ships, a behavior
attributed to vessel noise, while cod and sole
have shown changes in swimming behavior when
exposed to recordings of pile driving, even at low
levels. Mass strandings of giant squid on the coast
of Spain in 2001 and 2003 correlated with seismic
testing using powerful air guns, and the animals
themselves exhibited lesions on tissues and
organs indicative of damage from blast pressure.14
In short, various studies have documented
increased stress, loss of anti-predator response,
habitat displacement, severe injury, and other
impacts in fish and invertebrates exposed to certain
sources of manmade noise.
However, the greatest amount of research on the
impact of noise on marine life involves marine
mammals, particularly whales. For example, the
powerful blasts used by industry to prospect for
offshore oil and gas have been shown to silence
endangered great whales and displace them over
vast areas of ocean, in some cases over hundreds
of thousands of square miles, undermining their
ability to feed or mate.15 Certain high-intensity
naval sonars are known to cause whales to strand,
sometimes in mass numbers; and to drive some
deep-diving species to dangerously alter their
diving behavior, leading to pathologies analogous
to severe decompression sickness in humans,
including bleeding around the brain and the
development of lesions in organ tissue.16
Of great long-term concern is the ongoing rise in
ambient noise, primarily from shipping, and its
impacts on marine life, including the low-frequency
great whales. According to Christopher Clark of
Cornell University, a blue whale that was born in
1940 would have seen its “acoustic bubble”—
the distance over which its vocalizations can travel
and be heard
—shrink from 1,000 to 100 miles
within its lifetime.17 It has also been found that
endangered right whales experience greater stress
amid the higher background noise produced by
commercial ships, and have been driven to increase
the volume of their calls in an attempt to surmount
it.18 Other endangered whales have been found to
increase their calling rates as background noise
rises, expending needed energy to unknown benefit,
and then to simply give up when the noise exceeds
even moderate levels.19 All of this matters because
of the whales’ fundamental dependence on sound:
to feed, to find mates, to detect predators, to keep
in contact with their calves, to maintain their social
bonds, to navigate and orient themselves in the
ocean: to do, in effect, everything they must do
to survive.
We humans place great importance on our ability
to hear clearly, and expend much effort to combat
noise pollution from industry, vehicles, and
airplanes—and understandably so. Yet we are
showing far less concern for the amount of noise we
are generating beneath the waves, causing stress
and damage in a world that is enveloped in sound in
a way we can barely imagine. Consider navigating
a world
—day after day, year after year
—where
your vision is severely impaired, blinded by fog or
mist; this is the world we are creating for marine
animals that depend on sound like we depend on
sight. And we are doing so at a time when marine
species must be resilient in order to adapt to the
rapidly changing conditions that ocean warming
and acidification and other stressors are producing.
We are only beginning to understand the significance
of sound in the marine environment, let alone the
damage we are causing by overpowering natural
sounds with our own deafening noises. The good
news is, having identified the existence of the
problem, we also have solutions at our fingertips.
SHIPPING NOISE
The human activity most responsible for spreading noise
beneath the waves is the traffic that transports people,
their possessions and their products.
More than 60,000 medium to very large commercial
vessels
—cargo ships, bulk carriers, container vessels,
tankers, cruise ships, and ferries
—are on the sea each
year.20 Ninety percent of global trade is seaborne;
the amount of trade carried by sea has quadrupled
since 1970 and doubled over the last two decades.21
The combination of increasing amounts of commercial
maritime trade, and increasing speed of the vessels
in that trade, has increased the amount of noise that
shipping traffic is spreading throughout the ocean.
Indeed, the sound of commercial shipping is virtually
ubiquitous throughout the global sea.
Underwater noise from large ships overlaps the
same low-frequency sounds that many whale
species use to communicate for feeding
and mating. In Cape Cod Bay, noise
pollution created primarily by shipping
traffic has shrunk the acoustic space
of right whales
—the distance over
which their vocalizations and the vocal
-
izations of other right whales can be heard
—by
80 percent, compromising the ability of this critically
endangered species to feed.22 Other endangered baleen
whales, like the great blue and fin whales that appear
to communicate across ocean basins, are similarly
compromised.23 But shipping noise affects even
species that use higher frequencies to survive. Studies
of Blainville’s and Cuvier’s beaked whales have shown
that vessels can affect diving and acoustic behavior,
interfering with foraging
—even when those vessels
are as far as 16 miles away.24 25 And shipping noise
has increasingly been shown to have a wide range of
impacts on fish and invertebrates, diminishing their
ability to feed, breed, and respond to predators.26
The extent to which shipping traffic can affect whales
was demonstrated through an accidental discovery in
the wake of the terrorist attacks of September 11, 2001.
Two teams of scientists were studying whale singing
and health in the Bay of Fundy when commercial
transportation around the world was brought to a
standstill to assess security measures following the
attacks. The slowdown resulted in a significant decrease
in underwater noise from large ships
—and the decrease
in noise coincided with a dramatic decrease in stressrelated hormones in the feces of North Atlantic right
whales. The study’s authors observed that the results
have “implications for all baleen whales in heavy ship
traffic areas and for recovery of this endangered right
whale population.”27
The reason large vessels are such a major factor in
underwater noise is that they produce sounds that
are both loud and predominantly low-frequency and,
as a consequence, can travel over large distances
underwater. While engine noise vibrating through
the hull contributes to the overall noise that ships
produce ship, the greatest contribution to vessel noise
is propeller cavitation, when large numbers of vacuum
bubbles created by the motion of propellers collapse.28
The fact that propeller cavitation is such a significant
factor in the noise generated by shipping may prove to
be a boon in addressing that noise. Heavily-cavitating
propellers are inefficient, because cavitation is a form
of turbulence that creates extra drag on the propeller
blades, so that greater energy is required to drive the
ships; meanwhile the constant implosion of air bubbles
eats away at the propellers themselves.29 Reducing
cavitation is therefore in the best interests of both marine
life and the shipping industry.
Simple calculations suggest that the overall contribution
to ambient noise from shipping is dominated by the
noisiest 10 percent of vessels.30 These are also the
vessels for which it is likely that noise-reduction
measures will be the most effective. In April 2014,
the International Maritime Organization adopted a
set of guidelines for reducing shipping noise, noting
that, for example: “Propellers should be designed
and selected in order to reduce cavitation,” such as
by “optimizing propeller load, ensuring as uniform
water flow as possible into propellers (which can be
influenced by hull design), and careful selection of
the propeller characteristics.”31 Designing ships with
more efficient propellers can not only lead to cost
reductions, in terms of fuel use and maintenance
costs for the shipping companies themselves, it
can also result in significant reductions in shipping
noise, theoretically making this an issue with a
solution that is eminently desirable to all parties.
In addition to design of propellers and hull
structures, vessel speed also plays a role in
overall noise output. By slowing down, vessels
can significantly reduce the noise they produce.32
With the slim profit margins and higher fuel costs
in recent years, many shipping companies are
already seeking ways in which to improve their
energy and cost-efficiency. Through slow steaming
and construction of larger ships that are more
cost-effective they are able to transport more
goods at a lower cost. This is a win-win for the
industry and marine life, improving companies’
bottom lines while reducing their contribution to
ocean noise. Now is the time to take advantage
of this desire to develop more energy-efficient
vessels by gaining commitments from major
shipping companies to slow steaming, costeffective retrofit and maintenance of older
vessels, and more efficient and quieter vessel
design during construction of new fleets.
SEISMIC TESTING
Talk of the impacts of offshore oil development on
marine life almost invariably conjures up images of
seabirds and sea otters covered in tar-like goo, and
rocky beaches painted black. But even without such
disasters as the Exxon Valdez or Deepwater Horizon,
long before platforms are constructed or drills driven
deep into the seabed, oil and gas exploration has
significant impacts on the marine environment.
Seismic exploration is driven by a global fleet of
approximately 100 specialized vessels, roughly
20 percent of which are conducting field operations
at any one time.33 Behind them, they tow arrays
of as many as 48 guns of differently-sized
chambers: guns that fire not munitions, but air.
That air, released under extremely high pressure,
creates a powerful sound wave that penetrates
miles beneath the seafloor and ricochets upward
and outward; examination of the reflected sound
waves allows industry to map ocean geology
and determine the likeliest locations of oil and
gas deposits.
To yield high acoustic intensities, multiple air guns
are fired with precise timing to produce a coherent
pulse of sound. During a survey, guns are fired at
regular intervals
—every 10 to 15 seconds, up to
24 hours per day, for weeks or months at a
time
—as the towing source vessel moves slowly
ahead.34 To be on a ship in the vicinity of a seismic
vessel is to be subjected to a repetitious “thunk
thunk thunk” as the reverberating blasts, expanding
outward, make contact with the hull. Underwater,
the seismic blasts have an astonishing range.
A number of studies have reported airgun surveys
raising background levels of noise in the ocean
from several thousand miles away; the noise is
so significant, even from such a great distance,
that it drowns out recordings of whales and other
naturally ambient sounds.35
Unsurprisingly, the scientific record shows that
industrial airgun surveys have a large environmental
footprint. In the areas of oil and gas development
off Russia’s Sakhalin Island, whales were recorded
leaving their feeding areas during surveys only to
return days after the surveys stopped
—a clear
indicator of habitat displacement. Many types of
marine mammals have reacted strongly to the
intense sound of seismic surveys, including harbor
porpoises, sperm whales, and foraging, breeding,
and migrating baleen whales, with silencing and
habitat abandonment seen over enormous areas
of ocean.36 Effects can be severe. Researchers
have expressed concern that, in Arctic Canada, the
noise from seismic testing has prompted narwhals
to remain in coastal summering waters until well
into fall and early winter, leaving them vulnerable
to entrapment by encroaching ice. More than 1000
narwhals are believed to have died in three such
incidents around Baffin Bay, Canada, from 2008
through 2010.37
Nor are marine mammals the only concern.
Airguns have been shown to dramatically depress
catch rates of various commercial species (by 40
to 80 percent) over thousands of square miles
around a single array, leading fishermen in some
parts of the world to seek industry compensation
for their losses.38 Other impacts on commercially
harvested fish include habitat abandonment—a
likely explanation for the fallen catch rates—reduced
reproductive performance, and hearing loss.39
In an attempt to reduce the impact of seismic blasts
on cetaceans and other marine life, U.S. regula
-
tions require visual observers to examine the area
for marine mammals for a period of at least 30
minutes before a seismic survey can begin. Then it
must ramp up slowly by firing first one seismic gun
and then others over a period of 20 to 40 minutes,
slowly increasing the volume level in the hope that
marine animals will leave. However, should a whale
or other marine mammal appear within an exclusion
zone of about 500 meters from the center of the
seismic array, the operation must shut down, and
visual examination must resume for 30 minutes.37
Yet as numerous biologists have recognized, this ap
-
proach is inadequate at preventing severe acute effects. Seismic surveys take place around the clock,
in all weather conditions, and marine mammals are
difficult to spot under the best of circumstances.
No matter how professional the monitoring, a large
number of protected species will simply escape
detection, leaving them unprotected from the acute
impacts of airgun blasting. In addition, shutting
down a source in response to animals often means
a line is repeated resulting in more overall noise and
higher risk. And maintaining a small safety zone is
completely ineffective at tempering impacts from a
sound that reverberates over distances of hundreds
or even thousands of miles.41
A more effective approach is to address the
location, duration and intensity of seismic surveys.
As the U.S. Marine Mammal Commission has
explained, avoiding “repetitious seismic surveys
of the same area when a single survey would
suffice”—by, for example, having one entity conduct
a thorough survey and then other companies use that
survey’s data
—could drastically reduce the impact
while providing the same results. Surveys should be
conducted only in areas and at times when whale
density is known to be low; some habitat is simply
too important to be subjected to the transformative
impacts of seismic. More fundamentally, various
technological alternatives are being developed that
may be at least as effective as airguns in oil and gas
exploration, without as significantly deleterious
effects on marine life. Most notable of these is
vibroseis, which generates sounds through vibrations
rather than airgun explosions; the technique is more
commonly used on land, but commercial marine
vibroseis techniques exist only in prototype. Marine
vibroseis and other “quieting” technologies lack the
funding, support and, perhaps most importantly,
the regulatory mandate needed to expedite their
development and commercial adoption, despite the
fact that oil companies clearly have the resources
to devote to such research.42 “Shoot first and ask
questions later” is not a sustainable approach.
NOTES 1 Convention on Biological Diversity. 2012. Scientific synthesis
on the impacts of underwater noise on marine and coastal
biodiversity and habitats. UN Doc. UNEP/ CBD/ SBSTTA/ 16/
INF/ 12.
2 Shupak, A., Sharoni, Z., Yanir, Y., Keynan, Y., Alfie, Y., and
Halpern, P. 2005. Underwater hearing and sound localization
with and without an air interface. Otology and Neurotology 26:
127-130.
3 Cranford, T.W., and Krysl, P. 2015. Fin whale sound recep
-
tion mechanisms: Skull vibration enables low-frequency
hearing. PLoS ONE 10(1):e0116222. doi:10.1371/journal.
pone.0116222.
4 Versluis, M., Schmitz, B., von der Heydt, A., and Lohse, D.
2000. How snapping shrimp snap: Through cavitating bubbles.
Science 289: 2114-2117.
5 Zelick, R., Mann, D.A., and Popper, A.N. 1999. Acoustic
communication in fishes and frogs. In: Fay, R.R, and Popper,
A.N. Comparative Hearing: Fish and Amphibians. New York:
Springer-Verlag.
6 Lamar, C. 2012. ‘this incredible Antarctic seal’s calls sound
like Pink Floyd and beatboxing.’ Io9.com, January 31. http://
io9.com/5880846/this-incredible-antarctic-seals-call-soundslike-pink-floyd-and-beatboxing
7 Angier, N. 2008. ‘Who is the walrus?’ New York Times, May 20.
http://www.nytimes.com/2008/05/20/science/20walrus.
html?pagewanted=all
8 Hoyt, E. 1990. Orca: the Whale Called Killer. London: Robert
Hale (revised edition), p. 43
9 Payne, R.S., and McVay, S. 1971. Songs of humpback whales.
Science 173: 585-597.
10 Payne, R. 1995. Among Whales. New York: Scribner, p. 145
11 http://www.listenforwhales.org/page.aspx?pid=442
12 Bortolotti, D. 2008. Wild Blue: A Natural History of the World’s
Largest Animal. New York: St. Martin’s Press, p.170
13 National Research Council. 2003. Ocean noise and marine
mammals. Washington, D.C.: National Academics Press.
14 Convention on Biological Diversity. 2012. ‘Scientific synthesis
on the impacts of underwater noise on coastal and marine
biodiversity and habitats.’ March 12.
15 E.g., Blackwell, S.B., Nations, C.S., McDonald, T.L., Greene,
Jr., C.R., Thode, A.M., Guerra, M., and Macrander, M., 2013.
Effects of airgun sounds on bowhead whale calling rates in
the Alaskan Beaufort Sea, Marine Mammal Science 29(4):
E342-E365 (2013). Castellote, M., Clark, C.W., and Lammers,
M.O. 2012. Acoustic and behavioural changes by fin whales
(Balaenoptera physalus) in response to shipping and airgun
noise. Biological Conservation 147: 115-122. Cerchio, S.,
Strindberg, S., Collins, T., Bennett, C., and Rosenbaum, H.
2014. Seismic surveys negatively affect humpback whale
singing activity off Northern Angola. PLoS ONE 9(3): e86464.
doi:10.1371/journal.pone.0086464.
16 E.g., Fernández, A., Edwards, J.F., Rodriguez, F., Espinosa de
los Monteros, A., Herraez, P., Castro, P., Jaber, J.R., Martin,
V., and Arbelo, M. 2015. ‘Gas and fat embolic syndrome’
involving a mass stranding of beaked whales (Family Ziphiidae)
exposed to anthropogenic sonar signals. Veterinary Pathology
42: 446-457.
17 See Clark, C.W., Ellison, W.T., Southall, B.L., Hatch, L., Van
Parijs, S.M., Frankel, A., and Ponirakis, D. 2009. Acoustic
masking in marine ecosystems: Intuitions, analysis, and impli
-
cation, Marine Ecology Progress Series 395: 201-222.
18 Rolland, R.M., Parks, S.E., Hunt, K.E., Castellote, M., Corkeron,
P.J., Nowacek, D.P., Wasser, S.K., and Kraus, S.D., 2012.
Evidence that ship noise increases stress in right whales,
Proceedings of the Royal Society B: Biological Sciences
doi:10.1098/rspb.2011.2429. Parks, S.E., Johnson, M.,
Nowacek, D., and Tyack, P.L. 2011. Individual right whales
call louder in increased environmental noise. Biology Letters
7:33-35. See also Hatch, L.T., Clark, C.W., van Parijs, S.M.,
Frankel, A.S., and Ponirakis, D.W. 2012. Quantifying loss of
acoustic communication space for right whales in and around
a U.S. National Marine Sanctuary. Conservation Biology 26:
983-994.
19 Blackwell, S.B., Nations, C.S., McDonald, T.L., Thode, A.M.,
Mathias, D., Kim, K.H., Greene, Jr., C.R., and Macrander, M.
2015. Effects of airgun sounds on bowhead whale calling
rates: Evidence for two behavioral thresholds. PLoS ONE
10(6): e0125720. doi:10.1371/journal.pone. 0125720.
20 Equasis. 2015. The world merchant fleet in 2014. Available
from the European Maritime Safety Agency, Lisbon, Portugal.
21 Tournadre, J. 2014. ‘Anthropogenic pressure on the open
ocean: The growth of ship traffic revealed by altimeter data
analysis.’ Geophysical Research Letters, 41 (22): 7924-7932
22 Hatch, L.T., Clark, C.W., van Parijs, S.M., Frankel, A.S., and Pon
-
irakis, D.W. 2012. Quantifying loss of acoustic communication
space for right whales in and around a U.S. National Marine
Sanctuary. Conservation Biology 26: 983-994.
23 Clark, C.W., Ellison, W.T., Southall, B.L., Hatch, L., Van Parijs,
S.M., Frankel, A., and Ponirakis, D. 2009. Acoustic masking
in marine ecosystems: intuitions, analysis, and implication.
Marine Ecology Progress Series 395: 201-222.
24 Aguilar Soto, N., et al. 2006. ‘Does intense ship noise disrupt
foraging in deep-diving Cuvier’s beaked whales (Ziphius caviros
-
tris)?’ Marine Mammal Science 22(3): 690-699
25 Pirotta, E., et al. 2012. ‘Vessel noise affects beaked whale
behavior: Results of a dedicated acoustic response study.’
PLoS One 7(8): e42535. doi:10.1371/journal.pone.0042535
26 E.g., Nedelec, S.L., Radford, A.N., Simpson, S.D., Nedelec,
B., Lecchini, D., and Mills, S.C. 2014. Anthropogenic noise
playback impairs embryonic development and increases
mortality in a marine invertebrate. Scientific Reports 4: 5891
(doi:10.1038/srep05891). Simpson, S.D., Purser, J., and
Radford, A.N. 2015. Anthropogenic noise compromises anti
-
predator behavior in European eels. Global Change Biology 21:
586-593.
27 Rolland, R.M., et al. 2012. ‘Evidence that ship noise increas
-
es stress in right whales.’ Proceedings of the Royal Society B
doi: 10.1098/rspb.2011.2429
28 International Maritime Organization. 2010. Noise from
commercial shipping and its adverse impacts on marine life.
Report of the Correspondence Group presented to IMO Marine
Environment Protection Committee (MEPC 61/19).
29 ‘Cavitation for beginners: Building the fastest ship in the
world
—video’ The Guardian, 17 August 2012. http://www.
theguardian.com/science/video/2012/aug/17/cavitation-be
-
ginners-building-fastest-ship-world-video
30 Leaper, R.,and Renilson, M. 2012. A review of practical
methods for reducing underwater noise pollution from large
commercial vessels. International Journal of Maritime Engineering 154: A79-A88.
31 http://ocr.org/pdfs/policy/2014_Shipping_Noise_Guidelines_
IMO.pdf
32 Leaper, R., Renilson, M., and Ryan, C. 2014. Reducing underwater noise from large commercial ships: Current status and
future directions. Journal of Ocean Technology 9(1): 51-69.
33 Hildebrand, J.A. 2009. Marine Ecology Progress Series 395:
5-20.
34 Id. For examples of seismic surveys, see, e.g.: NMFS. 2012.
Issuance of incidental take authorization. Federal Register 77:
27720-27736 (typical 3D survey). Spectrum Geo. 2015. NMFS
Incidental harassment authorization application.
Available at nmfs.gov (typical 2D survey).
35 E.g., Nieukirk, S.L., et al. 2012. ‘Sounds from airguns and fin
whales recorded in the mid-Atlantic Ocean, 1999–2009.’ Journal of the Acoustical Society of America 131 (2): 1102-1112.
36 Bain, D.E., and R. Williams. 2006. ‘Long-range effects of air
gun noise on marine mammals: Responses as a function of
received sound level and distance.’ IWC-SC/58E35.
37 Heide-Jorgensen, M.P. et al. 2013. ‘Narwhals and seismic
exploration: Is seismic noise increasing the risk of ice entrap
-
ment?’ Biological Conservation 158: 50-54
38 E.g., Engås, A., Løkkeborg, S., Ona, E., and Soldal, A.V. 1996.
Effects of seismic shooting on local abundance and catch
rates of cod (Gadus morhua) and haddock (Melanogrammus
aeglefinus), Canadian Journal of Fisheries and Aquatic Sciences
53: 2238-2249.
39 E.g., Slotte, A., Hansen, K., Dalen, J., and Ona, E. 2004.
Acoustic mapping of pelagic fish distribution and abundance
in relation to a seismic shooting area off the Norwegian west
coast, Fisheries Research 67:143-150. McCauley, R., Fewtrell,
J., and Popper, A.N. 2003. High intensity anthropogenic sound
damages fish ears, Journal of the Acoustical Society of America
113: 638-642.
40 See, e.g., NMFS. 2012. Issuance of incidental take authoriza
-
tion. Federal Register 77: 27720-27736.
41 E.g., Parsons, E.C.M., Dolman, S.J., Jasny, M., Rose, N.A., Sim
-
monds, M.P., and Wright, A.J. 2009. A critique of the UK’s JNCC
seismic survey guidelines for minimising acoustic disturbance
to marine mammals: Best practise? Marine Pollution Bulletin
58: 643-651.
42 LGL and MAI. 2011. ‘Environmental Assessment of Marine
Vibroseis.’ LGL Rep. TA4604-1; JIP contract 22 07-12. Rep.
from LGL Ltd., environ. res. assoc., King City, Ont., Canada, and
Marine Acoustics Inc., Arlington, VA, U.S.A., for Joint Industry
Programme, E&P Sound and Marine Life, Intern. Assoc. of Oil &
Gas Producers, London, U.K. 207 p
ability to create and hear natural sounds is vital to
their existence. Numerous species, from whales to
dolphins to shrimps, use sound to communicate,
navigate, and feed. Indeed, because the underwater
world can be severely limiting to other senses such
as vision, for many marine species sound is the
primary means to communicate and learn about
their environment.1 Humans don’t hear well beneath
the waves because our ear canals fill with water,
preventing our eardrums from vibrating,2 but marine
species sense sound in different ways; in many
cases, they literally hear sound in their bones.3
The sounds they make, the reasons they make them,
and the manner in which they do so, are as various
as ocean life itself. Pistol shrimps snap their giant
claws with such force that the action produces an
air bubble of sound powerful enough to stun the
shrimps’ prey.4 During courtship, at times of stress,
or as a territorial display, fish may generate noises
—described variously as grunts, groans, thuds, and
barks—by grinding their teeth or tightening and
loosening muscles to vibrate their swim bladders.5
Leopard seals in the waters surrounding the Antarctic
have been reported to emit ultrasonic sounds when
chasing prey, while the haunting sounds made
by Weddell seals evoke the sound effects of old
science-fiction movies and have been likened to
techno music and a Pink Floyd concert.6 At the
other end of the global ocean, walruses produce a
repertoire of vocalizations that have been described
as sounding like “a circus, a construction site,
a Road Runner cartoon…They whistle, beep, rasp,
strum, bark, and knock. They make bell tones,
jackhammer drills, train track clatters, and the
rubber-band boing of Wile E. Coyote being bonked
on the head.”7
To listen through a hydrophone, or underwater
microphone, to a pod of orcas on a hunt is to marvel
at the social interplay and cooperation conveyed
through their squeaks and clicks. Orca researcher
Paul Spong has noted that, “Living in the ocean,
these social mammals use sound to navigate,
find their food, and stay in touch with each other.
It’s a very complex and varied world of sound.”8
But the deepest, loudest, and farthest-carrying
noises in the underwater animal kingdom are the
ones that are made by the great whales.
The Songs of the Whales
The most famous ocean sounds of all are the
‘songs’ of humpback whales, long known to
mariners but first truly examined by Roger and
Katherine Payne and Scott McVay in 1967.
9 It
was the Paynes and McVay who discovered that
the strange, haunting moans of humpbacks could
truly be called songs, in that they involve repeated
sequences called “themes,” each generally between
15 and 30 minutes long, that are, in Roger Payne’s
words, “strung together without pauses so that a
long singing session is an exuberant, uninterrupted
river of sound that can flow for twenty-four hours or
longer.” Katherine Payne made a further discovery:
that the songs change over time; at any given
moment, all the singing humpback whales in a
particular region sing the same song, but they tinker
with and alter that song, a piece at a time, until,
over the course of several years, the song they all
sing has evolved considerably. Only males sing; the
songs are delivered with such power that, in Roger
Payne’s telling, “When you swim up next to a singing
whale through the cool, blue water, the song is so
loud, so thundering in your chest and head, you feel
as if someone is pressing you to a wall with their
open palms, shaking you until your teeth rattle.”10
Although humpback vocalizations are the most
celebrated and melodious of those made by whales,
they are not the only ones.
Right whales produce a fantastic variety of calls for
different social situations, from low rumblings like
those from a speaker with the bass turned up, to
sounds like a gunshot or a firework disappearing
into the sky, and ‘screams’ that could be mistaken,
out of context, for the cries of an elephant.
Different vocalizations perform different functions.
Short “upcalls” for example, which are made most
frequently, seem to be greetings, a way for each
whale to announce its presence to others in
the area; gunshot sounds, produced by males,
are most likely reproductive in nature, and the
elephant-like screams are made when right whales
gather in groups at the surface.11
The long, rumbling moans emitted by blue whales
propagate immense distances across the ocean and
have been picked up by hydrophones from distances
of 700 miles. It had long been thought that blues
and fins were largely solitary animals; now biologists
believe they organize themselves in long-distance
“herds,” not in each other’s sight but in constant
contact across ocean basins because of their
powerful vocalizations.12
There are many other natural noises beneath the
waves. The crashing of waves on the shore, a
familiar sound to beachcombers, also reverberates
beneath the surface. Increased wind strength can
affect wave action at the sea’s surface, raising
background levels of sound. In Polar regions, sea ice
dynamics
—including ice formation and deformation,
pressure ridging, and cracking
—increase ambient
noise levels over a broad range of frequencies.
In the Antarctic, acoustic signals from icebergs
include harmonically rich tremors that can last
from hours to days.13
Such background sounds, no matter how loud or how
well propagated, have been present in the global
ocean for millions of years and have always been a
part of whales’ existence. Over the past century or so
however, new sounds have entered the ocean realm.
Anthropogenic Noise Interferes and Overwhelms
As the ocean has become industrialized, new noises
have entered the undersea world, in many cases
drowning out not only these background sounds
but also causing physical harm to whales and other
marine life. Explosives, pile-drivers, seismic airguns,
and sonar produce acute noise that can induce
stress, disrupt vital behavior, and even cause
physical injury in species as diverse as fish, squid
and cuttlefish, and marine mammals.
For example, studies have found damage to the
swim bladders or inner ear sensory hair cells
of some fish as a result of being exposed to
explosions, pile driving, and seismic blasts.
Catches of fish such as cod, haddock, and rockfish
have declined significantly within large areas around
seismic air gun surveys; cod and herring have been
observed swimming away from ships, a behavior
attributed to vessel noise, while cod and sole
have shown changes in swimming behavior when
exposed to recordings of pile driving, even at low
levels. Mass strandings of giant squid on the coast
of Spain in 2001 and 2003 correlated with seismic
testing using powerful air guns, and the animals
themselves exhibited lesions on tissues and
organs indicative of damage from blast pressure.14
In short, various studies have documented
increased stress, loss of anti-predator response,
habitat displacement, severe injury, and other
impacts in fish and invertebrates exposed to certain
sources of manmade noise.
However, the greatest amount of research on the
impact of noise on marine life involves marine
mammals, particularly whales. For example, the
powerful blasts used by industry to prospect for
offshore oil and gas have been shown to silence
endangered great whales and displace them over
vast areas of ocean, in some cases over hundreds
of thousands of square miles, undermining their
ability to feed or mate.15 Certain high-intensity
naval sonars are known to cause whales to strand,
sometimes in mass numbers; and to drive some
deep-diving species to dangerously alter their
diving behavior, leading to pathologies analogous
to severe decompression sickness in humans,
including bleeding around the brain and the
development of lesions in organ tissue.16
Of great long-term concern is the ongoing rise in
ambient noise, primarily from shipping, and its
impacts on marine life, including the low-frequency
great whales. According to Christopher Clark of
Cornell University, a blue whale that was born in
1940 would have seen its “acoustic bubble”—
the distance over which its vocalizations can travel
and be heard
—shrink from 1,000 to 100 miles
within its lifetime.17 It has also been found that
endangered right whales experience greater stress
amid the higher background noise produced by
commercial ships, and have been driven to increase
the volume of their calls in an attempt to surmount
it.18 Other endangered whales have been found to
increase their calling rates as background noise
rises, expending needed energy to unknown benefit,
and then to simply give up when the noise exceeds
even moderate levels.19 All of this matters because
of the whales’ fundamental dependence on sound:
to feed, to find mates, to detect predators, to keep
in contact with their calves, to maintain their social
bonds, to navigate and orient themselves in the
ocean: to do, in effect, everything they must do
to survive.
We humans place great importance on our ability
to hear clearly, and expend much effort to combat
noise pollution from industry, vehicles, and
airplanes—and understandably so. Yet we are
showing far less concern for the amount of noise we
are generating beneath the waves, causing stress
and damage in a world that is enveloped in sound in
a way we can barely imagine. Consider navigating
a world
—day after day, year after year
—where
your vision is severely impaired, blinded by fog or
mist; this is the world we are creating for marine
animals that depend on sound like we depend on
sight. And we are doing so at a time when marine
species must be resilient in order to adapt to the
rapidly changing conditions that ocean warming
and acidification and other stressors are producing.
We are only beginning to understand the significance
of sound in the marine environment, let alone the
damage we are causing by overpowering natural
sounds with our own deafening noises. The good
news is, having identified the existence of the
problem, we also have solutions at our fingertips.
SHIPPING NOISE
The human activity most responsible for spreading noise
beneath the waves is the traffic that transports people,
their possessions and their products.
More than 60,000 medium to very large commercial
vessels
—cargo ships, bulk carriers, container vessels,
tankers, cruise ships, and ferries
—are on the sea each
year.20 Ninety percent of global trade is seaborne;
the amount of trade carried by sea has quadrupled
since 1970 and doubled over the last two decades.21
The combination of increasing amounts of commercial
maritime trade, and increasing speed of the vessels
in that trade, has increased the amount of noise that
shipping traffic is spreading throughout the ocean.
Indeed, the sound of commercial shipping is virtually
ubiquitous throughout the global sea.
Underwater noise from large ships overlaps the
same low-frequency sounds that many whale
species use to communicate for feeding
and mating. In Cape Cod Bay, noise
pollution created primarily by shipping
traffic has shrunk the acoustic space
of right whales
—the distance over
which their vocalizations and the vocal
-
izations of other right whales can be heard
—by
80 percent, compromising the ability of this critically
endangered species to feed.22 Other endangered baleen
whales, like the great blue and fin whales that appear
to communicate across ocean basins, are similarly
compromised.23 But shipping noise affects even
species that use higher frequencies to survive. Studies
of Blainville’s and Cuvier’s beaked whales have shown
that vessels can affect diving and acoustic behavior,
interfering with foraging
—even when those vessels
are as far as 16 miles away.24 25 And shipping noise
has increasingly been shown to have a wide range of
impacts on fish and invertebrates, diminishing their
ability to feed, breed, and respond to predators.26
The extent to which shipping traffic can affect whales
was demonstrated through an accidental discovery in
the wake of the terrorist attacks of September 11, 2001.
Two teams of scientists were studying whale singing
and health in the Bay of Fundy when commercial
transportation around the world was brought to a
standstill to assess security measures following the
attacks. The slowdown resulted in a significant decrease
in underwater noise from large ships
—and the decrease
in noise coincided with a dramatic decrease in stressrelated hormones in the feces of North Atlantic right
whales. The study’s authors observed that the results
have “implications for all baleen whales in heavy ship
traffic areas and for recovery of this endangered right
whale population.”27
The reason large vessels are such a major factor in
underwater noise is that they produce sounds that
are both loud and predominantly low-frequency and,
as a consequence, can travel over large distances
underwater. While engine noise vibrating through
the hull contributes to the overall noise that ships
produce ship, the greatest contribution to vessel noise
is propeller cavitation, when large numbers of vacuum
bubbles created by the motion of propellers collapse.28
The fact that propeller cavitation is such a significant
factor in the noise generated by shipping may prove to
be a boon in addressing that noise. Heavily-cavitating
propellers are inefficient, because cavitation is a form
of turbulence that creates extra drag on the propeller
blades, so that greater energy is required to drive the
ships; meanwhile the constant implosion of air bubbles
eats away at the propellers themselves.29 Reducing
cavitation is therefore in the best interests of both marine
life and the shipping industry.
Simple calculations suggest that the overall contribution
to ambient noise from shipping is dominated by the
noisiest 10 percent of vessels.30 These are also the
vessels for which it is likely that noise-reduction
measures will be the most effective. In April 2014,
the International Maritime Organization adopted a
set of guidelines for reducing shipping noise, noting
that, for example: “Propellers should be designed
and selected in order to reduce cavitation,” such as
by “optimizing propeller load, ensuring as uniform
water flow as possible into propellers (which can be
influenced by hull design), and careful selection of
the propeller characteristics.”31 Designing ships with
more efficient propellers can not only lead to cost
reductions, in terms of fuel use and maintenance
costs for the shipping companies themselves, it
can also result in significant reductions in shipping
noise, theoretically making this an issue with a
solution that is eminently desirable to all parties.
In addition to design of propellers and hull
structures, vessel speed also plays a role in
overall noise output. By slowing down, vessels
can significantly reduce the noise they produce.32
With the slim profit margins and higher fuel costs
in recent years, many shipping companies are
already seeking ways in which to improve their
energy and cost-efficiency. Through slow steaming
and construction of larger ships that are more
cost-effective they are able to transport more
goods at a lower cost. This is a win-win for the
industry and marine life, improving companies’
bottom lines while reducing their contribution to
ocean noise. Now is the time to take advantage
of this desire to develop more energy-efficient
vessels by gaining commitments from major
shipping companies to slow steaming, costeffective retrofit and maintenance of older
vessels, and more efficient and quieter vessel
design during construction of new fleets.
SEISMIC TESTING
Talk of the impacts of offshore oil development on
marine life almost invariably conjures up images of
seabirds and sea otters covered in tar-like goo, and
rocky beaches painted black. But even without such
disasters as the Exxon Valdez or Deepwater Horizon,
long before platforms are constructed or drills driven
deep into the seabed, oil and gas exploration has
significant impacts on the marine environment.
Seismic exploration is driven by a global fleet of
approximately 100 specialized vessels, roughly
20 percent of which are conducting field operations
at any one time.33 Behind them, they tow arrays
of as many as 48 guns of differently-sized
chambers: guns that fire not munitions, but air.
That air, released under extremely high pressure,
creates a powerful sound wave that penetrates
miles beneath the seafloor and ricochets upward
and outward; examination of the reflected sound
waves allows industry to map ocean geology
and determine the likeliest locations of oil and
gas deposits.
To yield high acoustic intensities, multiple air guns
are fired with precise timing to produce a coherent
pulse of sound. During a survey, guns are fired at
regular intervals
—every 10 to 15 seconds, up to
24 hours per day, for weeks or months at a
time
—as the towing source vessel moves slowly
ahead.34 To be on a ship in the vicinity of a seismic
vessel is to be subjected to a repetitious “thunk
thunk thunk” as the reverberating blasts, expanding
outward, make contact with the hull. Underwater,
the seismic blasts have an astonishing range.
A number of studies have reported airgun surveys
raising background levels of noise in the ocean
from several thousand miles away; the noise is
so significant, even from such a great distance,
that it drowns out recordings of whales and other
naturally ambient sounds.35
Unsurprisingly, the scientific record shows that
industrial airgun surveys have a large environmental
footprint. In the areas of oil and gas development
off Russia’s Sakhalin Island, whales were recorded
leaving their feeding areas during surveys only to
return days after the surveys stopped
—a clear
indicator of habitat displacement. Many types of
marine mammals have reacted strongly to the
intense sound of seismic surveys, including harbor
porpoises, sperm whales, and foraging, breeding,
and migrating baleen whales, with silencing and
habitat abandonment seen over enormous areas
of ocean.36 Effects can be severe. Researchers
have expressed concern that, in Arctic Canada, the
noise from seismic testing has prompted narwhals
to remain in coastal summering waters until well
into fall and early winter, leaving them vulnerable
to entrapment by encroaching ice. More than 1000
narwhals are believed to have died in three such
incidents around Baffin Bay, Canada, from 2008
through 2010.37
Nor are marine mammals the only concern.
Airguns have been shown to dramatically depress
catch rates of various commercial species (by 40
to 80 percent) over thousands of square miles
around a single array, leading fishermen in some
parts of the world to seek industry compensation
for their losses.38 Other impacts on commercially
harvested fish include habitat abandonment—a
likely explanation for the fallen catch rates—reduced
reproductive performance, and hearing loss.39
In an attempt to reduce the impact of seismic blasts
on cetaceans and other marine life, U.S. regula
-
tions require visual observers to examine the area
for marine mammals for a period of at least 30
minutes before a seismic survey can begin. Then it
must ramp up slowly by firing first one seismic gun
and then others over a period of 20 to 40 minutes,
slowly increasing the volume level in the hope that
marine animals will leave. However, should a whale
or other marine mammal appear within an exclusion
zone of about 500 meters from the center of the
seismic array, the operation must shut down, and
visual examination must resume for 30 minutes.37
Yet as numerous biologists have recognized, this ap
-
proach is inadequate at preventing severe acute effects. Seismic surveys take place around the clock,
in all weather conditions, and marine mammals are
difficult to spot under the best of circumstances.
No matter how professional the monitoring, a large
number of protected species will simply escape
detection, leaving them unprotected from the acute
impacts of airgun blasting. In addition, shutting
down a source in response to animals often means
a line is repeated resulting in more overall noise and
higher risk. And maintaining a small safety zone is
completely ineffective at tempering impacts from a
sound that reverberates over distances of hundreds
or even thousands of miles.41
A more effective approach is to address the
location, duration and intensity of seismic surveys.
As the U.S. Marine Mammal Commission has
explained, avoiding “repetitious seismic surveys
of the same area when a single survey would
suffice”—by, for example, having one entity conduct
a thorough survey and then other companies use that
survey’s data
—could drastically reduce the impact
while providing the same results. Surveys should be
conducted only in areas and at times when whale
density is known to be low; some habitat is simply
too important to be subjected to the transformative
impacts of seismic. More fundamentally, various
technological alternatives are being developed that
may be at least as effective as airguns in oil and gas
exploration, without as significantly deleterious
effects on marine life. Most notable of these is
vibroseis, which generates sounds through vibrations
rather than airgun explosions; the technique is more
commonly used on land, but commercial marine
vibroseis techniques exist only in prototype. Marine
vibroseis and other “quieting” technologies lack the
funding, support and, perhaps most importantly,
the regulatory mandate needed to expedite their
development and commercial adoption, despite the
fact that oil companies clearly have the resources
to devote to such research.42 “Shoot first and ask
questions later” is not a sustainable approach.
NOTES 1 Convention on Biological Diversity. 2012. Scientific synthesis
on the impacts of underwater noise on marine and coastal
biodiversity and habitats. UN Doc. UNEP/ CBD/ SBSTTA/ 16/
INF/ 12.
2 Shupak, A., Sharoni, Z., Yanir, Y., Keynan, Y., Alfie, Y., and
Halpern, P. 2005. Underwater hearing and sound localization
with and without an air interface. Otology and Neurotology 26:
127-130.
3 Cranford, T.W., and Krysl, P. 2015. Fin whale sound recep
-
tion mechanisms: Skull vibration enables low-frequency
hearing. PLoS ONE 10(1):e0116222. doi:10.1371/journal.
pone.0116222.
4 Versluis, M., Schmitz, B., von der Heydt, A., and Lohse, D.
2000. How snapping shrimp snap: Through cavitating bubbles.
Science 289: 2114-2117.
5 Zelick, R., Mann, D.A., and Popper, A.N. 1999. Acoustic
communication in fishes and frogs. In: Fay, R.R, and Popper,
A.N. Comparative Hearing: Fish and Amphibians. New York:
Springer-Verlag.
6 Lamar, C. 2012. ‘this incredible Antarctic seal’s calls sound
like Pink Floyd and beatboxing.’ Io9.com, January 31. http://
io9.com/5880846/this-incredible-antarctic-seals-call-soundslike-pink-floyd-and-beatboxing
7 Angier, N. 2008. ‘Who is the walrus?’ New York Times, May 20.
http://www.nytimes.com/2008/05/20/science/20walrus.
html?pagewanted=all
8 Hoyt, E. 1990. Orca: the Whale Called Killer. London: Robert
Hale (revised edition), p. 43
9 Payne, R.S., and McVay, S. 1971. Songs of humpback whales.
Science 173: 585-597.
10 Payne, R. 1995. Among Whales. New York: Scribner, p. 145
11 http://www.listenforwhales.org/page.aspx?pid=442
12 Bortolotti, D. 2008. Wild Blue: A Natural History of the World’s
Largest Animal. New York: St. Martin’s Press, p.170
13 National Research Council. 2003. Ocean noise and marine
mammals. Washington, D.C.: National Academics Press.
14 Convention on Biological Diversity. 2012. ‘Scientific synthesis
on the impacts of underwater noise on coastal and marine
biodiversity and habitats.’ March 12.
15 E.g., Blackwell, S.B., Nations, C.S., McDonald, T.L., Greene,
Jr., C.R., Thode, A.M., Guerra, M., and Macrander, M., 2013.
Effects of airgun sounds on bowhead whale calling rates in
the Alaskan Beaufort Sea, Marine Mammal Science 29(4):
E342-E365 (2013). Castellote, M., Clark, C.W., and Lammers,
M.O. 2012. Acoustic and behavioural changes by fin whales
(Balaenoptera physalus) in response to shipping and airgun
noise. Biological Conservation 147: 115-122. Cerchio, S.,
Strindberg, S., Collins, T., Bennett, C., and Rosenbaum, H.
2014. Seismic surveys negatively affect humpback whale
singing activity off Northern Angola. PLoS ONE 9(3): e86464.
doi:10.1371/journal.pone.0086464.
16 E.g., Fernández, A., Edwards, J.F., Rodriguez, F., Espinosa de
los Monteros, A., Herraez, P., Castro, P., Jaber, J.R., Martin,
V., and Arbelo, M. 2015. ‘Gas and fat embolic syndrome’
involving a mass stranding of beaked whales (Family Ziphiidae)
exposed to anthropogenic sonar signals. Veterinary Pathology
42: 446-457.
17 See Clark, C.W., Ellison, W.T., Southall, B.L., Hatch, L., Van
Parijs, S.M., Frankel, A., and Ponirakis, D. 2009. Acoustic
masking in marine ecosystems: Intuitions, analysis, and impli
-
cation, Marine Ecology Progress Series 395: 201-222.
18 Rolland, R.M., Parks, S.E., Hunt, K.E., Castellote, M., Corkeron,
P.J., Nowacek, D.P., Wasser, S.K., and Kraus, S.D., 2012.
Evidence that ship noise increases stress in right whales,
Proceedings of the Royal Society B: Biological Sciences
doi:10.1098/rspb.2011.2429. Parks, S.E., Johnson, M.,
Nowacek, D., and Tyack, P.L. 2011. Individual right whales
call louder in increased environmental noise. Biology Letters
7:33-35. See also Hatch, L.T., Clark, C.W., van Parijs, S.M.,
Frankel, A.S., and Ponirakis, D.W. 2012. Quantifying loss of
acoustic communication space for right whales in and around
a U.S. National Marine Sanctuary. Conservation Biology 26:
983-994.
19 Blackwell, S.B., Nations, C.S., McDonald, T.L., Thode, A.M.,
Mathias, D., Kim, K.H., Greene, Jr., C.R., and Macrander, M.
2015. Effects of airgun sounds on bowhead whale calling
rates: Evidence for two behavioral thresholds. PLoS ONE
10(6): e0125720. doi:10.1371/journal.pone. 0125720.
20 Equasis. 2015. The world merchant fleet in 2014. Available
from the European Maritime Safety Agency, Lisbon, Portugal.
21 Tournadre, J. 2014. ‘Anthropogenic pressure on the open
ocean: The growth of ship traffic revealed by altimeter data
analysis.’ Geophysical Research Letters, 41 (22): 7924-7932
22 Hatch, L.T., Clark, C.W., van Parijs, S.M., Frankel, A.S., and Pon
-
irakis, D.W. 2012. Quantifying loss of acoustic communication
space for right whales in and around a U.S. National Marine
Sanctuary. Conservation Biology 26: 983-994.
23 Clark, C.W., Ellison, W.T., Southall, B.L., Hatch, L., Van Parijs,
S.M., Frankel, A., and Ponirakis, D. 2009. Acoustic masking
in marine ecosystems: intuitions, analysis, and implication.
Marine Ecology Progress Series 395: 201-222.
24 Aguilar Soto, N., et al. 2006. ‘Does intense ship noise disrupt
foraging in deep-diving Cuvier’s beaked whales (Ziphius caviros
-
tris)?’ Marine Mammal Science 22(3): 690-699
25 Pirotta, E., et al. 2012. ‘Vessel noise affects beaked whale
behavior: Results of a dedicated acoustic response study.’
PLoS One 7(8): e42535. doi:10.1371/journal.pone.0042535
26 E.g., Nedelec, S.L., Radford, A.N., Simpson, S.D., Nedelec,
B., Lecchini, D., and Mills, S.C. 2014. Anthropogenic noise
playback impairs embryonic development and increases
mortality in a marine invertebrate. Scientific Reports 4: 5891
(doi:10.1038/srep05891). Simpson, S.D., Purser, J., and
Radford, A.N. 2015. Anthropogenic noise compromises anti
-
predator behavior in European eels. Global Change Biology 21:
586-593.
27 Rolland, R.M., et al. 2012. ‘Evidence that ship noise increas
-
es stress in right whales.’ Proceedings of the Royal Society B
doi: 10.1098/rspb.2011.2429
28 International Maritime Organization. 2010. Noise from
commercial shipping and its adverse impacts on marine life.
Report of the Correspondence Group presented to IMO Marine
Environment Protection Committee (MEPC 61/19).
29 ‘Cavitation for beginners: Building the fastest ship in the
world
—video’ The Guardian, 17 August 2012. http://www.
theguardian.com/science/video/2012/aug/17/cavitation-be
-
ginners-building-fastest-ship-world-video
30 Leaper, R.,and Renilson, M. 2012. A review of practical
methods for reducing underwater noise pollution from large
commercial vessels. International Journal of Maritime Engineering 154: A79-A88.
31 http://ocr.org/pdfs/policy/2014_Shipping_Noise_Guidelines_
IMO.pdf
32 Leaper, R., Renilson, M., and Ryan, C. 2014. Reducing underwater noise from large commercial ships: Current status and
future directions. Journal of Ocean Technology 9(1): 51-69.
33 Hildebrand, J.A. 2009. Marine Ecology Progress Series 395:
5-20.
34 Id. For examples of seismic surveys, see, e.g.: NMFS. 2012.
Issuance of incidental take authorization. Federal Register 77:
27720-27736 (typical 3D survey). Spectrum Geo. 2015. NMFS
Incidental harassment authorization application.
Available at nmfs.gov (typical 2D survey).
35 E.g., Nieukirk, S.L., et al. 2012. ‘Sounds from airguns and fin
whales recorded in the mid-Atlantic Ocean, 1999–2009.’ Journal of the Acoustical Society of America 131 (2): 1102-1112.
36 Bain, D.E., and R. Williams. 2006. ‘Long-range effects of air
gun noise on marine mammals: Responses as a function of
received sound level and distance.’ IWC-SC/58E35.
37 Heide-Jorgensen, M.P. et al. 2013. ‘Narwhals and seismic
exploration: Is seismic noise increasing the risk of ice entrap
-
ment?’ Biological Conservation 158: 50-54
38 E.g., Engås, A., Løkkeborg, S., Ona, E., and Soldal, A.V. 1996.
Effects of seismic shooting on local abundance and catch
rates of cod (Gadus morhua) and haddock (Melanogrammus
aeglefinus), Canadian Journal of Fisheries and Aquatic Sciences
53: 2238-2249.
39 E.g., Slotte, A., Hansen, K., Dalen, J., and Ona, E. 2004.
Acoustic mapping of pelagic fish distribution and abundance
in relation to a seismic shooting area off the Norwegian west
coast, Fisheries Research 67:143-150. McCauley, R., Fewtrell,
J., and Popper, A.N. 2003. High intensity anthropogenic sound
damages fish ears, Journal of the Acoustical Society of America
113: 638-642.
40 See, e.g., NMFS. 2012. Issuance of incidental take authoriza
-
tion. Federal Register 77: 27720-27736.
41 E.g., Parsons, E.C.M., Dolman, S.J., Jasny, M., Rose, N.A., Sim
-
monds, M.P., and Wright, A.J. 2009. A critique of the UK’s JNCC
seismic survey guidelines for minimising acoustic disturbance
to marine mammals: Best practise? Marine Pollution Bulletin
58: 643-651.
42 LGL and MAI. 2011. ‘Environmental Assessment of Marine
Vibroseis.’ LGL Rep. TA4604-1; JIP contract 22 07-12. Rep.
from LGL Ltd., environ. res. assoc., King City, Ont., Canada, and
Marine Acoustics Inc., Arlington, VA, U.S.A., for Joint Industry
Programme, E&P Sound and Marine Life, Intern. Assoc. of Oil &
Gas Producers, London, U.K. 207 p
No comments:
Post a Comment