Before the EPA
Trans-Tasman Resources Ltd Iron sands Extraction Project
In the matter of the Exclusive Economic Zone and Continental Shelf (Environmental
Effects) Act 2012
And
In the matter of a board appointed to consider a marine consent application made by
Trans-Tasman Resources Ltd to undertake iron ore extraction and processing
operations offshore in the South Taranaki Bight
Summary Statement of Evidence of Dr Simon John Childerhouse on
behalf of Trans-Tasman Resources Ltd
31 March 2014
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Executive Summary
1.
While the exact nature of the underwater noise from the Trans-Tasman Resources
Ltd (TTR) dredging and associated operations is unknown, the noise level has been
estimated by Mr Hegley in his evidence at 172 dB re 1μPa at 1m. Based on a review
of the literature from other dredging operations I have used a conservative (higher)
estimated noise level of 188 dB re 1μPa at 1m. Assuming the noise levels from this
operation are broadly comparable to other similar dredges, some generalisations can
be made. This assumption is critical to the accuracy of these findings and should be
verified. Given that the TTR suction dredge does not use a cutter head and will be
primarily extracting sand rather than gravel, it is probable that the TTR operation will
generate less noise than the other dredges I have reviewed.
2.
Dredges produce noise across a broad range of frequencies that overlap with the
hearing range of some marine mammal groups. In general, the dominant frequency
ranges from dredges is lower than the sensitivity range for most marine mammal
groups, with the exception of some baleen whales. Therefore noise from the dredge
is likely to have a lower level of impact for cetaceans with hearing sensitivities in the
high and mid-frequency bands.
3.
Given that the estimated source levels of the dredges published in the literature are
considerably lower than those of a seismic survey, the acoustic footprint of a
dredging operation would be much smaller than that of any seismic survey conducted
in the same area. However, it is important to note that a seismic survey is generally
short term in nature (e.g. weeks to months) and spans a large operational area
whereas the dredging operations proposed by TTR occur in a relatively small area
but over a 20-year period.
4.
If noise levels of the dredge are comparable to those of shipping as the literature
suggests, then behavioural, rather than physiological effects (e.g. Temporary
Threshold Shift (TTS) or Permanent Threshold Shift (PTS)) are likely to be of highest
concern with respect to noise generated from the proposed activity. There exists the
potential for behavioural modification (e.g. exclusion from the area) from the activity
but given that the esonified area is likely to be relatively small (e.g. an area
potentially several km around the source) the effect on individuals, let alone species
in the greater South Taranaki Bight (STB), is likely to be limited.
5.
While the specific source level of the TTR dredge operation is not known, none of the
levels recorded from other dredges reported in the literature approach recognised
international underwater noise standards such as the Sound Exposure Level (SEL)
for Permanent Threshold Shift (hearing loss) in cetaceans from continuous noise (i.e.
Southall et al. 2007). Given that the TTR suction dredge does not use a cutter head
and will be primarily extracting sand rather than gravel, it is probable that the TTR
operation will generate less noise than the other dredges reviewed here. Mr Hegley,
in his evidence, has estimated that the noise from the dredging operation and
associated activities is significantly lower than the conservative values used in my
evidence. In my opinion, this provides reasonable evidence that physical damage
(e.g. TTS or PTS) from dredge noise is unlikely for marine mammals.
6.
While permanent or temporary hearing loss arising from increased noise from the
proposed activity seem unlikely, the slow movement of the dredge and the long
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duration of the operation (i.e. 20 years) warrant careful consideration of behavioural
effects, especially for any threatened species.
7.
I have not seen any evidence that would lead me to believe that the TTR operational
area is of particular biological importance to any marine mammal species although
they are likely to be present in the broader area at certain times of year. Humpback
and southern right whales are known to migrate through Cook Strait in winter and
blue whales feed at upwellings in the STB area (Torres 2013). While Maui‟s dolphins
and/or Hector‟s dolphins are found in very low numbers in the STB region, the
operational area is at the margins of the southern-most recognised range for Maui‟s
dolphins. It appears very unlikely that Maui‟s dolphins are present in the TTR
operational area given that the majority of their distribution is considerably further
north of this site.
8.
The extent to which all of these species depend upon the proposed dredging area is
believed to be low given that no species other than common dolphins have been
recorded during aerial and boat based surveys of the area undertaken by Cawthorn
(2013) and the Department of Conservation (DOC). Therefore I consider the
likelihood of noise impacts on these species within the operational area to be low and
outside the operational area to be unlikely. Furthermore, if any marine mammals are
found in the vicinity of the dredge operation and are disturbed by noise, they have the
ability to move away at a rate much faster than that of the factory and crawler (i.e. 70
metres per hour).
9.
There is little information about the impacts of noise from dredging on fish. While
most research has focused on the impacts of seismic surveys, with some impacts
recorded, it is difficult extrapolate from these studies to dredging operations with
lower noise levels. As for marine mammals, given the relatively small area over
which noise is likely to be heard, any impacts are likely to be localised to the
immediate area around the dredge location and have little or no impact on fish or
fisheries in other areas. Given that the moderate levels of noise likely generated from
the proposed operation fall below proposed international standards for marine
mammals with respect to continuous operations, little impact from noise is
anticipated. Less is known about impacts on fish, but again given the moderate levels
of noise from the operation, any impacts are likely to be highly localised to the
immediate vicinity of the operational area and have little effect, if any, on fisheries
outside of this area.
Resolved issues
10.
I believe that the Joint Statement of Experts in the field of effects on marine
mammals including noise represents a good summary of these issues. The
paragraph numbers in this section correspond to paragraph numbers in the Joint
Statement of Experts in the field of effects on marine mammals including noise.
Some of the key areas of agreement include:
a. That all the marine mammal species listed in the South Taranaki Bight
Factual Baseline Environmental report (MacDiarmid et al. 2011) could occur
within the TTR mining area (paragraph 13);
b. That the south Taranaki Coast is considered to be part of the historic natural
range for Maui‟s dolphins, and is on the margins of their current range. While
most records and sightings of Maui‟s dolphins are between the Kaipara
Harbour and Raglan, Maui‟s dolphins have been recorded as far south as
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Whanganui with their relative density decreasing southward of Cape Egmont
(paragraph 17);
c. Blue whales (reported from elsewhere in the world) usually feed in waters
deeper than 100m but can also feed in shallow waters depending on the
abundance of food supply. Krill patches could move into the TTR mining area
and therefore blue whales could follow and feed there. However, the TTR
mining area may represent the edge of the blue whale feeding area but
feeding may still extend into the mining area on occasion (paragraph 28);
d. Beaked whales are unlikely to be found in the TTR mining area or in waters
less than 200 m deep (paragraph 30);
e. Insufficient data are available for most marine mammal species that use the
South Taranaki Bight to determine their status (e.g. abundance) or the
significance of the location for them (paragraph 43);
f.
That it is important to correctly characterise the noise levels and frequencies
from the proposed operations. This is necessary in order to gauge any
potential impacts on marine mammals (paragraph 54);
g. It was agreed that it would not be appropriate to rely solely on a condition that
required management action in response to observed changes in marine
mammal behaviour (paragraph 60);
h. The experts agreed that it is important to consider not only the sound level but
also the frequency spectra of any noise (paragraph 65); and
i.
That any consent conditions need to address the influence of the noise on the
ability of the marine mammals to communicate as well as other potential
impacts of noise (paragraph 71).
Unresolved issues
11.
I believe that the Joint Statement of Experts in the field of effects on marine
mammals including noise represents a good summary of these issues. The
paragraph numbers in this section correspond to paragraph numbers in the Joint
Statement of Experts in the field of effects on marine mammals including noise.
Some of the key unresolved issues include:
a. That there was no agreement among the experts on the noise levels and
frequencies produced by the proposed operation or the sound propagation
models (paragraph 57);
b. That setting a noise limit at a distance from the operation is an appropriate
management approach. Further discussion would be needed to specify this
limit and distance and the expert conferencing group agreed to further
discussing this issue. The group was unable to reach agreement on a sound
level or distance to use as a condition (paragraph 66) but subsequent to this a
draft condition was proposed that met with the approval of most of the group
(see paragraph 34 of my Summary Evidence);
c. There was no agreement on a compliance monitoring regime (paragraph 67);
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d. There was no agreement on consent conditions or mitigation options
(paragraph 73);
e. That cumulative impacts are an important consideration. The experts also
agreed that while individual impacts can be difficult to assess accurately, it is
still important to try and assess potential cumulative impacts (paragraph 75);
and
f.
The experts agreed that they had insufficient time to fully consider the issue
of cumulative impact for any marine mammal and, while recognising its
importance, are unable to present advice on cumulative impacts (paragraph
78).
Responses to those unresolved issues
12.
My opinion about the unresolved issues are:
a. While Mr Hegley has provided an estimate of the noise levels and frequencies
produced by the proposed operation, it will require empirical measurement of
the actual noise of the TTR operation once it is operating to confirm the noise
and frequency outputs (re. Joint Statement of experts on marine mammals
and noise paragraph 57);
b. The expert group is continuing to discuss the setting of a noise limit at a
distance from the operation as an appropriate management approach. I am
hopeful that by the time of the presentation of the expert evidence, an
agreement may be reached (re. Joint Statement of experts on marine
mammals and noise paragraph 66);
c. I believe that the recommendations in the Joint Conferencing Statement
prepared by Planning Experts makes some useful suggestions and that the
elements of the proposed EMMP in the set of conditions provided with the
above Joint Conferencing Statement provide a useful starting point for a
compliance monitoring regime and conditions (re. Joint Statement of experts
on marine mammals and noise paragraphs 67 and 73);
d. Some additional specific comments on conditions are provided in paragraph
31-38 of this Executive Summary (re. Joint Statement of experts on marine
mammals and noise paragraphs 67 and 73);
e. I do not believe that it is possible to quantitatively evaluate cumulative
impacts and that the advice in the Joint Statement of experts on marine
mammals represents the best available. (re. Joint Statement of experts on
marine mammals and noise paragraph 75 and 78).
Evidence Associate Professor Elizabeth Slooten for KASM
13.
Assoc. Prof. Slooten notes in her evidence (paragraph 74) that “simple threshold
criteria based on exposure levels are not useful” in assessing potential impacts on
marine mammals and that experiments using a BACI design spanning 3 years before
and after an activity would be required. I agree that such experiments could be useful
in assessing impacts but given the apparent low density of marine mammals in the
survey area and the potentially low effect and size of the activity, any such
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experiment would likely suffer from low statistical power reducing the utility of any
results (as Assoc. Prof. Slooten herself notes in her paragraph 60). I also agree that
simple threshold criteria are not that useful but the use and application of threshold
levels derived from M-weighted Sound Exposure Level models (Southall et al. 2007)
developed specifically for marine mammals represents international best practice as
noted by both Prof. Würsig and the authors of the URS review (2013) on noise
provided to the EPA. This is the approach that I have taken in assessing impacts on
marine mammals.
14.
Assoc. Prof.‟s Slooten‟s evidence (paragraph 20) suggests that beaked whales and
sperm whales may use the area and therefore could potentially be impacted from
operational noise. I believe it is highly unlikely that these species will be present in
the operational area as both species are deep water species and the dredging area
is only approximately 20-40 m in depth. Beaked and sperm whales typically inhabit
offshore waters that are at least 400 meters deep and therefore may be present in
the outer reaches of the South Taranaki Bight region. I do note that several beaked
whales have stranded along the Taranaki coast over the last few decades but it is
generally accepted that the distribution of strandings is not a reliable representation
of the normal distribution of a deep water species.
15.
The distribution of southern right whales is discussed by Assoc. Prof. Slooten
(paragraph 30). While I agree that the data used in the habitat suitability models has
not been collected systematically, it does represent the best data set available. While
there is little doubt that southern right whales are found in the South Taranaki Bight
region, they are very rare visitors. A recent paper by Carroll et al. (2013) reported
only 125 sightings of southern right whales around all of New Zealand between 2003
and 2010 and this was while the Department of Conservation had an active and high
profile reporting programme in place. Of these 125 only 3 were from the South
Taranaki Bight area suggesting that while southern right whales are found in the
South Taranaki Bight region, they are very rare visitors and while there may be
behavioural effects (e.g. avoidance of the dredge site) for an individual, any potential
impacts from noise at the population level would be negligible.
Evidence of Professor Bernd Würsig for DOC
16.
In reference to the sound propagation models used by Mr Hegley and myself in our
evidence, Prof. Würsig comments (paragraph 34) that “Such models of acoustic
transmission become very complicated very quickly, and the basic ones presented
are (in my opinion) unlikely to be realistic”. I noted in my original evidence that the
model I used to estimate sound transmission loss was simplistic and recognised at
that time that a more complex model would better characterise received sound levels
away from the source. Mr Hegley, in his evidence for TTR, provided a more
sophisticated sound transmission loss model using his estimate of the source levels
from the dredging operation. The URS (2014) report on the assessment of noise
comments on Mr Hegley‟s propagation model noting that, “The approach taken
appears reasonable on the basis of the source noise levels used by Mr Hegley”.
Recognising the simplicity and limitations of my original propagation model, I have
revised my Sound Exposure Level (SEL) calculations to follow the model of Mr
Hegley but still use my more conservation (higher) source level, which differs from Mr
Hegley‟s estimate. These revisions are discussed further in paragraph 25 of this
Executive Summary.
17.
Prof. Würsig outlines a major recommendation in his paragraph 35 that
“…anthropogenic (non-pulsive) sounds at all frequency levels should not exceed 130
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dB (RMS) at 1 km from the noise source(s)”. I note that this level is less conservative
(lower) than the threshold value that I used in my evidence, which was based on a
Sound Pressure Level (SPL) of 120 dB re 1 μPa for behavioural responses as taken
from Southall et al. (2007) and Finneran & Jenkins (2012). Prof. Würsig and I have
cited different noise levels as being appropriate thresholds for marine mammals from
the same source (i.e. Southall et al. 2007). The differences lie in the interpretation of
these levels. I have used the most conservative, baseline level for any behavioural
response (i.e. Southall et al. 2007 behavioural response levels 1-9) of marine
mammals. Prof. Würsig has used a less conservative level for only behavioural
response levels 5-9 as in his expert opinion, “…brief and mild to moderate
disruptions of behaviours are not likely to be biologically meaningful”.
18.
I accept that Prof. Würsig‟s criterion is a reasonable guideline but do note that is it
very conservative (lower) in comparison to the DOC 2013 Code of Conduct for
Minimising Acoustic Disturbance to Marine Mammals from Seismic Survey
Operations (the Code). The Code states, “If sound levels are predicted to exceed
either 171 dB re 1 µPa2-s at distances corresponding to the relevant mitigation
zones for Species of Concern or 186 dB re 1 µPa2-s at 200 m, consideration will be
given to either extending the radius of the mitigation zone or limiting acoustic source
power accordingly”. Again, noting the differences between seismic surveys (i.e.
continuous non-directional noise) and dredging activities (i.e. pulsed directional
noise).
19.
I agree with the conclusion of Prof. Würsig as stated in paragraph 36 of his evidence
that, “…detrimental hearing loss, such as a permanent threshold shift of hearing, is
not likely to be of concern. Nevertheless, as a major recommendation to come from
my assessment, detailed in situ sound measurements per frequency bands need to
be made at the source(s) and at least 1 km from the source. These kind of
measurements are generally made at variable distances in hundreds of metres
increments, going out to several kilometres (Würsig and Greene 2002 provide an
example). If sound intensities at the source(s) are louder than estimated in the TTR
submission, then potential hearing and physical effects (as also detailed in Southall
et al. 2007) need to be taken into account”.
Evidence of Andrew Baxter for DOC
20.
While I recognise the potential utility of the NZ Code of Conduct for Seismic Surveys
in exploring mitigation options for this operation, I agree with Mr Baxter‟s assessment
in his paragraph 54 that, “The Code is specific to the operational and sound
characteristics of seismic surveys. The Code is not directly transferable to other
activities such as seabed mining which involve different operational needs and
different noise characteristics (e.g. continuous non-directional noise from a stationary
source rather than the pulsed directional noise from a mobile airgun array)”.
21.
In his paragraph 59, I believe that Mr Baxter accurately characterises the status of
Maui‟s dolphins in south Taranaki as, “There are comparatively few records along the
south Taranaki coast. The south Taranaki coast is considered to be part of the
historical natural range for Maui’s dolphins, and on the margins of their current
range”. He also notes in paragraph 96 that five aerial and six boat surveys have been
undertaken in South Taranaki searching for dolphins and no Maui‟s or Hector‟s
dolphins have been seen. This is important when considering any potential noise or
other impacts on them.
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22.
Mr Baxter states in his paragraph 86, “I recommend a condition of consent that limits
frequency-dependent sound levels to a biologically meaningful and acceptable level
at a set distance from the operation”. I agree that it is important to understand and
determine a biologically meaningful and acceptable level of noise and therefore I
have followed international best practice (e.g. Southall et al. 2007) in estimating such
levels in my evidence.
23.
I agree with Mr Baxter in his paragraph 87 that baseline aerial surveys should be
undertaken for more than a single year and that an expert marine mammal peer
group should review the design and results. Given the existing survey effort and
assumed encounter rates, it may be possible to estimate the effective survey
coverage that would be required to achieve a certain level of precision in addressing
questions about potential impact. This would ensure that the survey would be able to
robustly answer the question it was set out to achieve. A similar process would also
be advantageous for the proposed acoustic project.
URS Assessment of effects in relation to noise from the Trans-Tasman Resources
marine consent application (February 2014)
24.
The URS Report (paragraph 28) notes that they agree with my conservative estimate
of dredge source level, “In the absence of any source level frequency data, the
adoption of 188 dB re 1μPa at 1m if further considered appropriate as it provides
added conservatism”.
25.
As identified earlier in paragraph 16 of this Executive Summary, I accept that I used a
very simplistic propagation model to estimate received sound levels. The data from
Mr Hegley‟s propagation model was not available to me at the time of writing my
original evidence and therefore a simple model was used instead. In paragraphs 3234 of their report, the authors of the URS Report provide details of a reanalysis of the
data in Table 3 of my original evidence using the updated propagation model defined
by Mr Hegley in his original evidence. Had the authors of the URS Report not
undertaken the reanalysis, then I would have as part of this Executive Summary now
that the Mr Hegley data are available. I appreciate the revision, have checked the
calculations, and accept the new results as a more realistic estimation of the noise
propagation. I also agree that Column 3 from the Table in paragraph 33 of the URS
report should be used for further calculations of SPL and SELs. Furthermore, I agree
that the Table in paragraph 34 of the URS Report represents a useful improvement
over my original work and should be used for the conservative interpretation of
potential impacts of noise on marine mammals.
26.
I note and accept that the assessment in the URS Report (paragraph 35) which
suggests that behavioural responses occur between 500 m to 4,000 m for low and
medium frequency cetaceans assuming a source level of 188 dB re 1μPa at 1m. In
the same paragraph, I note that they agree with my assessment that behavioural
effects rather than TTS or PTS are the main concerns and that it is unlikely that any
physical injuries would occur for marine mammals.
27.
The authors of the URS Report agree (paragraph 37) with my conclusion that if the
sonar unit on the crawler has an operating frequency of 720 kHz then there will be no
effects on marine mammals. However, they conclude that if high power, midfrequency sonar is used, it will overlap with the frequency sensitivities of a range of
marine mammal species. This statement is correct and could potentially result in
behavioural effects for beaked whales for example but, as I noted in para 14 of this
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Executive Summary, I believe the presence of beaked whales in the dredging
operational area is highly unlikely.
28.
The authors of the URS Report (paragraph 38) agree that my observations about the
effect of noise on fish “…appear appropriate and reasonable”
29.
With respect to the project specific controls identified by URS, I support the following
issues identified in their report (paragraph 50):
a. The use of soft starts for all equipment;
b. 30 minute pre-start observations without marine mammals within the
mitigation zone;
c. All records of marine mammal sightings to be kept. Further to this, I
recommend that records of marine mammal sightings are forwarded to DOC;
30.
With respect to the project-specific controls identified by URS, I believe that the
following issues identified in their report (paragraph 50) require further consideration:
a. As a general principle, the 2013 Code of Conduct for Minimising Acoustic
Disturbance to Marine Mammals from Seismic Survey Operations (the Code)
is an excellent starting point for developing mitigation options. However, it is
important to note that it has been specifically designed to address mitigation
needs for seismic surveys and, while some parallels with this operation are
apparent, it is not appropriate to adopt the whole Code for this operation.
Therefore, the application of the Code would require careful review for
suitability and appropriateness for this dredging operation. This issue was
also highlighted by Mr Baxter and is referred to in paragraph 18 of my
Executive Summary. One of the fundamental differences between these
operations is that seismic surveys generally move quickly through the water
and will move towards marine mammals emitting high level pulsed sounds,
whereas the TTR dredge operation is so slow, it is effectively stationary in
comparison to any marine mammals nearby (and is easily avoided by them)
and emits continuous but lower level noise.
b. „Behavioural response mitigation zone‟ – I do not understand what this means
in this context. Under the Code, this has various definitions specific to
different species and noise sources. Further discussion would be useful.
c. Using suitably qualified or experienced marine mammal observers (MMOs)
and presumably Passive Acoustic Monitoring (PAM) operators – again these
have specific definitions under the Code that are not necessarily directly
applicable to the operation of a dredge. I would recommend further discussion
on this point. An option may be for marine bridge crew to be trained as MMOs
as is used in some dredging operations in Australia but this would require
careful consideration as bridge crew already have large, existing workloads.
This will, of course, depend on the exact requirements for monitoring and
perhaps a revised set of criteria for dredge-specific MMOs.
d. Use of a PAM system – While I believe that this a useful area to explore, I am
not convinced that this would be feasible or necessarily useful unless done
properly. Having previously investigated the deployment of PAM systems
from drill ships and rigs, I think that it would be logistically challenging for this
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operation. However, the main issue will be potential background noise from
the ship‟s engines and generators and the ability to get the hydrophone
elements sufficiently removed from any noise source. Normally on a seismic
survey, the hydrophones are towed several hundred metres away from the
vessel and seismic source but this could be difficult to achieve on a FPSO but
perhaps could be deployed from a support vessel (i.e. anchor handler).
Therefore, I do not believe that a real time PAM system is required. Perhaps
a more useful option would be the deployment of moored PAM systems
around the operation that could be recovered regularly and the data retrieved
and then the units redeployed. It would be useful to understand the effective
detection distance by PAM systems of vocalising cetaceans while the dredge
and associated operations are running to understand how effective this
mitigation may be. Admittedly, without some form of real-time acoustic
monitoring, night time observations will be not be possible but other mitigation
could be used (i.e. thermal imaging systems).
e. Shut downs – While this is a useful issue to consider, it requires further
careful consideration of exact shut down distances, species to which it applies
(i.e. The Code doesn‟t apply the same rules to all species), how it would be
applied if species were attracted to the FPSO (e.g. some dolphins can be
boat-positive) and should it only be individuals with a calf? Overall, I believe
that shutting down the operation if a marine mammal comes within a
mitigation zone is unnecessary as long as an appropriate noise level
threshold is set and the noise levels of the TTR operation are within this.
Again, it is important to bear in mind that shut downs of seismic surveys are
required as the noise source level is considerably higher than mining noise
and that the seismic survey also moves quickly through an area whereas the
TTR operation will be moving slow enough for any marine mammals to leave
the area if they are disturbed.
Comment on TTR’s proposed conditions
31.
I provide the following comments on the Joint Statement of Experts in the field of
mitigation in relation to marine mammals. The paragraph numbers in this section
correspond to paragraph numbers in Appendix A of the Joint Statement of Experts in
the field of mitigation.
32.
I agree that it is useful for the Technical Peer Review Group to invite marine mammal
experts to join the group from time to time (paragraph 14 (3)).
33.
I support the conditions proposed for marine mammals in paragraphs 49-56. In
addition, I make the following specific comments:
a. Paragraph 49 marine mammal surveys as set out in the TTR EMMP – there is
presently insufficient detail available in the EMMP. I make the following
suggestions related to this:
1. That regular aerial surveys should be undertaken for the duration of
the baseline sampling programme and that the aerial survey
methodology should be independently peer reviewed prior to
commencement;
2. That Passive Acoustic Monitoring using bottom mounted or fixed and
floating acoustic recorders be undertaken for the duration of the
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baseline sampling programme with a particular focus on the detection
of Maui‟s dolphins and blue whales. This work will complement the
aerial survey programme, particularly for species that are not readily
detected in aerial surveys; and
3. It may be useful to convene a marine mammal technical working
group to advise on the two issues above.
b. Paragraph 53 marine mammal observers (MMO) – it is important to provide a
description of who would be considered acceptable as a marine mammal
observer in terms of experience and training. Depending on exact
requirements, this could be a dedicated MMO or a bridge crew member
trained in marine mammal detection, identification and observation. Please
see some related comments in paragraph 30(c) of my Summary Statement.
c. Paragraph 54 passive acoustic monitoring (PAM) – while I am supportive of
this condition in principle, it requires some additional description as it is too
generic to be useful as it is presently written. Important considerations
including (i) what species are of interest (e.g. Maui‟s dolphins and blue
whales may both be of interest but would most likely require separate
monitoring systems given the large differences in the frequency range of their
vocalisations), (ii) is presence/absence information sufficient or is localisation
information required, (iii) is real time monitoring required (e.g. being able to
detect and localise vocalising cetaceans when they are actually in the
operational area) and (iv) is monitoring required for only the baseline
sampling programme or for the entire 20 year operation. The development of
a PAM system that could meet even some of these requirements is a highly
technical issue and would require some detailed consideration before a
robust PAM regime could be developed. My personal opinion is that, given
the low levels of noise likely from this operation, a real time monitoring PAM
system is not required but that it would be useful to have some PAM to detect
and record the presence of marine mammals in the operational area. I have
provided some related comments on this issue in paragraph 30(d) of my
Summary Statement.
d. Paragraph 55 vessel interactions – A noted in the Joint Statement of experts
on marine mammals (see paragraph 49 of that document), they agreed that
the risk of ship strike is low. Given this, and noting the slow speed of the
crawler and FPSO, I do not believe that any additional action other than
“observation and take all practical steps to avoid” are necessary and that
ceasing the mining operation until a whale or dolphin is clear is not required.
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34.
During subsequent discussions following the Joint Statement of Experts in the field of
effects on marine mammals including noise, the following draft noise conditions were
suggested. I support these as a practical measure to protect marine mammals.
a. The combined noise from the FPSO and Crawler operating under
representative full production conditions shall be measured nominally 10m
below the sea surface at 300m, 500m, 750m and 1000m from the port or
starboard side of the FPSO. The combined noise level at 500m shall not
exceed 130dB re 1µPa RMS linear in any one third octave band for the
following frequency ranges: low frequency 10-100 Hz, mid-frequency 10010,000 Hz, and high frequency >10,000 Hz
___________________________
Dr Simon Childerhouse
31 March 2014
Summary Statement of Evidence of Dr Simon John Childerhouse on behalf of Trans-Tasman Resources Ltd
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