Download Worldwide Guidelines to Mitigate the Effect of Seismic on Marine

P1-2-6
A Review: Worldwide Guidelines to Mitigate the Effect of Seismic on Marine Mammals
Maria Andersson
Hydenlyne Limited, Dorset, UK
Introduction
It is still unknown as to whether seismic surveys have detrimental effects on marine mammals.
However, work has arisen for Marine Mammal Observers (MMOs) and Passive Acoustic
Monitoring operators (PAM) as a result of concerns that marine mammals may suffer physical
(including physiological), perceptual, behavioural, and indirect effects (Marine Mammal
Commission, 2007) if exposed to airgun sources in close proximity.
There is some evidence that anthropogenic noise in the ocean can affect the ability of marine
mammals to communicate with each other. This excess noise in the environment can have a
perceptual effect on the animal by masking biologically significate sounds, which in turn may
reduce the range of their echolocation (Nakahara, 1999). If calls used to communicate with
conspecifics during feeding bouts are masked, feeding rates for that population may be reduced
(Nakahara, 1999). Indirectly this excess noise in the environment could have an effect on their
prey species which may also lead to reduced feeding rates (Gordon et al., 2004).
Vocalisations are often used for animals to determine kinship (Similä, 1997) providing information
on suitable mates. If these vocalisations are masked, it may disrupt reproductive behaviour. This
is seen in humpback whales (Megaptera novaeangliae), where males have been seen to modify
their sexual display by increasing their song length in response to sonar (Miller et al. 2000).
The most likely physical effect of noise to marine mammals would be shifts in their threshold of
hearing. Hearing damage may be in the form of temporary threshold shifts (TTS) or permanent
threshold shifts (PTS). The severity of TTS depends on the length of time that the animal is
exposed to the noise but recovery occurs within minutes to hours (Nachtigall et al. 2003).
Whereas PTS occurs as a result of chronic exposure from very high sound levels (Nachtigall et al.
2004). Richardson et al. (1995) considers that TTS and PTS is only really a problem if animals are
within a few hundred metres of a sound pressure level of high intensity, such as that of a large
seismic airgun array.
Therefore, the main principle involved in minimising the effect of offshore industry operations on
marine mammals is to ensure, where possible, that the animals are not exposed to high enough
levels of sound to cause a detrimental effect. For cetaceans the onset of PTS may occur around
230dB and for pinnipeds around 232dB (NOAA Technical Memorandum, 2016). During seismic
operations this can be achieved by delaying or stopping the sound source if marine mammals get
too close during operations. It can also be achieved by avoiding sensitive times/areas for marine
mammals keeping in mind migration routes and feeding and breeding hotspots.
Worldwide mitigation guidelines:
When consent is grated for a seismic survey to be conducted many countries make it a condition
of consent that certain guidelines are followed to protect marine mammals that may be subjected
to noise from a survey. However, guidelines differ a considerable amount between countries. The
guidelines outlined here are examples and changes may occur depending on the outcome of the
environmental impact assessment for a specific survey.
Pre-watch
All guidelines consist of a pre-watch period during which MMO or PAM operators must keep watch
to ensure a certain length of time has passed since the last sighting of a marine mammal within
the exclusion zone (UK) also known as the mitigation zone (USA) or precaution zone (Australia).
Across all guidelines this is generally a period of 30 minutes. Exceptions are seen in the UK,
Greenland and Ireland where when waters are deeper than 200m the period is increased to 60
minutes to allow for deep diving species to surface (JNCC, 2010; Kyhn et al., 2011; Department of
the arts, Heritage and the Gaeltacht, 2014). In areas where ACCOBAM guidelines apply if a
beaked whale is seen then the period increases to 120 minutes (www1).
Exclusion Zone (Also known as Mitigation Zone/Precaution Zone)
The exclusion zone in general is 500m. Exceptions to this occur in the USA, in Alaska and
California, where the zone is defined by a radius of how far a certain level of noise can travel
rather than a set distance. Therefore, the zone changes size depending on the environmental
factors of the survey area (The High Energy Seismic Survey Team, 1999; Statoil, 2010). Although
Australia and Brazil still use a 500m zone to indicate when shutdown procedures will be used, they
also use a variety of wider set zones for which different rules apply.
New Zealand takes a different approach from all the rest and has exclusion zones depending on
species and whether or not the animal has a calf with it or not (DoC, 2013). Here the guidelines
also change depending on the type of survey. A level 1 survey being any seismic survey using an
acoustic source with a total combined operational capacity exceeding 7 litres/427 cubic inches.
While a level 2 survey is any seismic survey using an acoustic source with a total combined
operational capacity of between 2.50–6.99 litres/151–426 cubic inches capacity (DoC, 2013).
[Table 1. Review of guidelines to minimise acoustic disturbance to marine mammals around the
world.]
Area
ACCOBAM
Marine
mammals
covered
All
Can PAM be
used to start
at night?
Monitoring
Zone
Sighting
free
period
Soft
Start
Shut
down
Yes
Beaked
whales
unlimited,
500m for all
other marine
mammals
120 min
for
beaked
whales,
30 min for
others
At least
30
minutes
For
all
marine
mammals
USA
Alaska
All
Yes
≥180 dB for
cetaceans and
≥190 dB for
pinnipeds
30 min
No
more
than 6
dB per
5min
For
all
marine
mammals
For
all
marine
mammals
USA
California
All
No
180dB radius
30 min
At
a
rate of
6dB per
min
USA GoM
All
Yes
500m
30 min
20-40
min
For
whale
species
Australia
baleen whales
+
larger
toothed
whales
Yes
3km
observation, 12km
low
power 500m
shut down
30 min
30 min
Power
down
and shut
down for
species
covered
Brazil
All
No
1km warning
area,
500m
safety area
30 min
20-40
min
For
all
marine
mammals
Canada
All
marine
mammals
threatened or
endangered
on Species at
Risk
Act
+cetaceans
and turtles
Yes
500m
30 min
20 min
For
species
covered
Greenland
Ireland
New
Zealand
UK
All
marine
mammals,
seabirds
recorded but
not mitigated
for.
All
All
All
500m safety
zone,
200m
injury zone
30
min
<200m,
60 min >
200m
20
minutes
If
any
marine
mammal
enter
injury
zone
then
reduce
output to
just
mitigation
gun
No
1000m
30
min
<200m,
60 min >
200m
40 min
No
Yes
1.5km – 200m
depending on
species/survey
*
10 min fur
seals, 30
min
for
cetaceans
20-40
min
For
species
of
concern
500m
30
min
<200m,
60 min >
200m
20-40
min
No
Yes
Yes
IAGC
All
Yes
500m
30 min
20 min
No
*Level 1 (L1) survey: 1.5km for species of concern with calves, 1km for species of concern without
calves, 200m for other marine mammals, Level 2 (L2) survey: 1km for species of concern with
calves, 600m for species of concern without calves, 200m for other marine mammals.
Table complied from manuscripts on guidelines around the world: www1; Statoil, 2010; HESS,
1999; BOEM, 2012; Department of Environment, Water, Heritage and the Arts, 2008; IBAMA,
2005; Department of Fisheries and Oceans Canada, 2007; Kyhn et al., 2011; Department of the
arts, Heritage and the Gaeltacht (2014); DoC, 2013; Danish Centre for Environment and Energy
(2015) JNCC, 2010; IAGC, 2015.
Soft start
A soft start procedure is implemented before airguns can be used at full power. This procedure
entails ramping up the airguns gradually, slowly increasing the noise output from a low level up to
operational level. The reasoning behind this is to give sufficient warning to marine mammals in the
vicinity to move away from the area before noise reaches a damaging level (JNCC, 2010). All
guidelines outlined in this paper have adopted the soft start procedure for which the airgun noise
output is gradually increased over a period of time, generally 20 – 40 minutes, or ramped up by
small increases in decibel output (The High Energy Seismic Survey Team, 1999).
Shut downs
Once in full production, guidelines for use in UK (JNCC, 2010) and Irish waters (Department of the
arts, Heritage and the Gaeltacht (2014) state that there is no more that can be done to prevent the
marine mammals getting close to the source. If marine mammals come within the exclusion zone
once the airguns are in full production they have come in of their own accord.
This is not the case for the rest of the guidelines outlined. Some guidelines include a power down
procedure in the case of Australian, Greenland and Alaskan guidelines (Department of
Environment, Water, Heritage and the Arts, 2008; Kyhn et al., 2011, Statoil, 2010). This results in
an immediate reduction in the number of operating energy sources should a marine mammal get
within a certain distance of the airguns. Others include a shutdown procedure where airguns are
shut down completely should a marine mammal come within a certain distance. Brazil even has a
warning zone allowing MMOs to warn the seismic team that there is a chance marine mammals
will be within the shutdown zone soon (IBAMA, 2005).
Some of these procedures are specific to certain marine mammals and not others (MMS, 2004;
Barkaszi et al. 2012; DoC, 2013; Department of Fisheries and Oceans Canada, 2007). In general,
the shutdown procedures sometimes do not apply to smaller dolphins and porpoise, this is
because they have peak hearing sensitivities in higher frequency ranges and therefore are less
likely to be disturbed by the lower frequency sound from seismic airguns. As a result, they are
less vulnerable to acoustic trauma (Department of Environment, Water, Heritage and the Arts,
2008).
In the absence of any regulations the IAGC will implement general guidelines including a 500m
exclusion zone, 30-minute pre-watch, and a soft start of at least 20 minutes (IAGC, 2015).
Conclusion
Mitigation guidelines have been put in place to minimise the possible detrimental effects seismic
surveys may have on marine mammals. Research shows that minimal disruption is caused if the
mammals are not exposed to noise over a certain level. Therefore, many countries are
implementing guidelines that attempt to reduce or delay noise output until the marine mammals
are clear of the area. It is understood that many countries are yet to make guidelines but may
well do in the future. By using mitigation guidelines, the offshore survey community can thrive in an
environmentally friend and sustainable manor.
References:
BOEM (2012) United States Department of the Interior Bureau of Ocean Energy Management
(BOEM) Bureau of Safety and Environmental Enforcement (BSEE) Gulf of Mexico Outer
Continental Shelf (OCS) Region.
Danish Centre for Environment and Energy (2015) Offshore seismic surveys in Greenland—
Guidelines to best environmental practices, environmental impact assessments and
environmental mitigation assessments.
Department of Art, Heritage and the Gaeltacht (2014) Guidance to Manage the Risk to Marine
Mammals from Man-made Sound Sources in Irish Water.
Department of Conservation (2013) 2013 Code of Conduct for minimising acoustic disturbance to
marine mammals from seismic survey operations. Department of Conservation, Wellington,
New Zealand.
Department of Environment, Water, Heritage and the Arts (2008) EPBC Act Policy Statement 2.1 –
Interaction between offshore seismic exploration and whales. Australian Government,
Australia.
Department of Fisheries and Ocean Canada (2007) Statement of Canadian Practice with respect
to the Mitigation of Seismic Sound in the Marine Environment. Department of Fisheries and
Ocean Canada, Canada.
IAGC (2015) Recommended Mitigation Measures for Cetaceans during Geophysical Operations.
IBAMA (2005) Guide for monitoring marine biota during seismic data acquisition activities. IBAMA,
Brazil.
JNCC (2010) Guidelines for minimising acoustic disturbance to marine mammals from seismic
surveys.
LGL Ltd and JASCO Research Ltd (2008) Marine mammal monitoring and mitigation during open
water seismic exploration by Shell Offshore INC in the Chukchi and Beaufort Seas July –
October 2008: 90-Day report. Anchorage, AK.
Marine Mammal Commission (2007) Marine mammals and noise: a sound approach to research
and management.
MMS (2004) Geological and geophysical exploration for mineral resources on the Gulf of Mexico
outer continental shelf: final programmatic environmental assessment. New Orleans: US
Department of the Interior Minerals Management Service Gulf of Mexico OCS Region
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Acoustical Society of America, 113(6), 3425-3429.
Nachtigall, P.E., Supin, A.Y., Pawloski, J. and Au, W.W.L. (2004) Temporary threshold shifts after
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Effects of Anthropogenic Sound on Marine Mammal Hearing—Underwater Acoustic
Thresholds for Onset of Permanent and Temporary Threshold Shifts. Office of Protected
Resources National Marine Fisheries Services, Silver Spring, MD, 20910
Richardson, W.J., Greene, C.R., Malme, C.I. and Thomson, D.H. (1995). Marine Mammals and
Noise. Academic Press, Inc, San Diego, CA.
Nakahara, F. (1999) Influences of the underwater man-made noise on acoustic behaviour of
dolphins. Otschui Marine Science, 24, 18-23.
Similä, T. (1997) Sonar observations of killer whales (Orcinus orca) feeding on herring schools.
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Southall, B.L., Bowels, A.E., Ellison, W.T., Finneran, J.J., Gentry, R.L., Greene Jr, C.R., Kastak,
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P.L. (2007) Marine mammal noise exposure criteria: Initial scientific recommendations.
Aquatic Mammals, 33(4), 122pp.
Statoil (2010) Marine Mammal Monitoring and Mitigation Plan for Marine Seismic Surveys of
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incidental harassment authorization for the non-lethal taking of marine mammals in
conjunction with a proposed marine 2D seismic program. Chukchi Sea, Alaska.
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www1: http://www.accobams.org