5. ENVIRONMENTAL IMPACT ASSESSMENT by sdsdfqw21

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									                               Proposed 3D seismic survey in Block 2B, West Coast, South Africa



5.      ENVIRONMENTAL IMPACT ASSESSMENT

This chapter describes and assesses the significance of potential impacts of the proposed 3D seismic
survey on the biophysical and socio-economic aspects of the affected environment. The potential impacts
of the proposed activities are addressed in three categories, namely:

1.      Seismic and support vessel (incl. helicopter) operation;
2.      Impacts of seismic noise on marine fauna; and
3.      Impacts of seismic activities on other users of the sea.

For each potential impact a table is provided that summarises the significance level assessment for that
impact. Mitigation measures that could ameliorate potential negative impacts or enhance potential
benefits are also proposed, where relevant.

Unless otherwise indicated, all potential impacts discussed below would be for the duration of the survey
only, i.e. short term (0 - 4 months), because of the high-energy marine environment and/or the transient
nature of survey activities.



5.1     IMPACT OF NORMAL SEISMIC / SUPPORT VESSEL AND HELICOPTER OPERATION

5.1.1    EMISSIONS TO THE ATMOSPHERE

Description of impact
Emissions to the atmosphere during the seismic survey may include exhaust gases from the use of diesel
as fuel for generators and motors, and the burning of wastes.

Diesel exhaust comprises mainly carbon dioxide (CO2) as well as several toxic gases such as nitrogen
oxides (NOX), sulphur oxides (SOX) and carbon monoxide (CO). In addition, diesel combustion can
produce hydrocarbons (THC and VOC). Smoke and particulate matter (soot) are also produced during
diesel combustion.

Incineration of waste onboard would also release soot as well as CO, CO2 and dioxins (depending on the
composition of waste). However, many vessels do not have an incinerator onboard. In these
circumstances solid waste would be stored separately onboard for later onshore disposal.

Assessment
The atmospheric emissions from the seismic and support vessel are expected to be similar to those from
similar diesel-powered vessel of comparable tonnage, with the addition of the emissions from the airgun
compressors. The volumes of solid waste incinerated on board, and hence also the volumes of
atmospheric emissions, would be minimal and incineration must comply with the relevant MARPOL
73/781 standards.

The potential impact of emissions to the atmosphere during seismic survey operations would be limited to
the survey area, of low intensity and is considered to be of VERY LOW significance with or without the
implementation of mitigation measures (see Table 5.1).


1
  MARPOL 73/78 is an International Convention for the Prevention of Pollution from Ships 1973, as modified by the Protocol of
1978 relating thereto. All vessels operating within the South African Exclusive Economic Zone are required to conform to legal
requirements for waste management and pollution control, including the Marine Pollution Act (No 2 of 1986 - which incorporate
Marpol 73/78 standards) and the Dumping at Sea Control Act (No 73 0f 1965). These Acts make provision for the discharge of
sewage, plastics, oil, galley wastes, hazardous liquids and packaged hazardous material.

CCA Environmental (Pty) Ltd                               5-1                                                   February 2009
                               Proposed 3D seismic survey in Block 2B, West Coast, South Africa




Mitigation
No mitigation is deemed necessary, but it is recommended that all diesel motors and generators receive
adequate maintenance to minimise soot and un-burnt diesel released to the atmosphere.

Table 5.1:        Impact of atmospheric emissions from the seismic and support vessel, and
                  helicopter.

                      Extent          Duration          Intensity      Probability      Significance   Confidence
Without
                   Local           Short-term        Low               Definite        Very Low        High
mitigation

With
                   Local           Short-term        Low               Definite        VERY LOW        High
mitigation



5.1.2     DISCHARGES/DISPOSAL TO THE SEA

Discharges from the seismic and support vessel to the marine environment include deck drainage,
machinery space drainage, sewage, galley wastes and solid wastes.



5.1.2.1    Deck drainage

Description of impact
Drainage of deck areas may result in small volumes of oils, solvents or cleaners being introduced into the
marine environment.

Assessment
Oils, solvents and cleaners could be introduced into the marine environment in small volumes through
spillage and drainage of deck areas. The volumes lost overboard are therefore likely to be very small. The
potential impact of deck drainage on the marine environment would therefore be of low intensity across
the survey area over the short-term, and is considered to be of VERY LOW significance with or without
mitigation (see Table 5.2).

Mitigation
The following measures are recommended for mitigation of deck drainage discharges from the seismic
and support vessel:

•       Deck drainage should be collected in oily water catchment systems;
•       Low-toxicity biodegradable detergents should be used in cleaning of all deck spillage;
•       Training and awareness of crew in spill management could minimise contamination; and
•       All hydraulic systems should be adequately maintained and hydraulic hoses should be frequently
        inspected.




CCA Environmental (Pty) Ltd                                5-2                                            February 2009
                               Proposed 3D seismic survey in Block 2B, West Coast, South Africa


Table 5.2:        Impact of deck drainage from the seismic and support vessel.

                       Extent           Duration          Intensity       Probability       Significance     Confidence
Without                                                                      Highly
                       Local           Short-term               Low                          Very Low           High
mitigation                                                                  Probable

                                                                             Highly
With mitigation        Local           Short-term               Low                         VERY LOW            High
                                                                            Probable



5.1.2.2    Machinery space drainage

Description of impact
Small volumes of oil such as diesel fuel, lubricants, grease, etc. used within the machinery space of the
seismic and support vessel could enter the marine environment.

Assessment
The seismic and support vessel must comply fully with international agreed standards regulated under
MARPOL 73/78. All machinery space drainage would pass through an oil/water filter to reduce the oil in
water concentration to 15 mg/l, in accordance with MARPOL 73/78 requirements.

Concentrations of oil reaching the marine environment through drainage of machinery spaces are
therefore expected to be low. The potential impact of such low concentrations would be of low intensity
and limited to the survey area over the short-term. The potential impact of machinery space drainage on
the marine environment is therefore considered to be of VERY LOW significance with or without
mitigation (see Table 5.3).

Mitigation
No mitigation measures are deemed necessary (assuming compliance with the Marpol 73/78 standards).

Table 5.3:        Impact of machinery space drainage from the seismic and support vessel.

                      Extent          Duration          Intensity      Probability      Significance       Confidence
Without                              Short- to                            Highly
                      Local                               Low                             Very Low            High
mitigation                          Medium-term                          Probable

With                                 Short- to                            Highly
                      Local                               Low                            VERY LOW             High
mitigation                          Medium-term                          Probable



5.1.2.3    Sewage

Description of impact
Sewage poses an organic and bacterial loading on the natural degradation processes of the sea,
resulting in an increased biological oxygen demand (BOD). This could result in anaerobic conditions in
the marine environment. Although treated sewage would also increase BOD, it does not pose a bacterial
load.

Assessment
The seismic survey is expected to take four months, depending on, amongst other things, weather
conditions. The volumes of sewage wastes released from the seismic and support vessel would be small
and comparable to volumes produced by vessels of similar crew compliment. All sewage would be


CCA Environmental (Pty) Ltd                               5-3                                                February 2009
                               Proposed 3D seismic survey in Block 2B, West Coast, South Africa


treated to the required Marpol 73/78 standard prior to release into the marine environment, where the
high wind and wave energy is expected to result in rapid dispersal.

The potential impact of sewage effluent from the seismic and support vessel on the marine environment
is expected to be limited to the survey area over the short-term, and is therefore considered to be of
VERY LOW significance with or without mitigation (see Table 5.4).

Mitigation
No mitigation measures are recommended (assuming sewage discharges are in compliance with the
Marpol 73/78 standards).

Table 5.4:        Impact of sewage effluent discharge from the seismic and support vessel.

                      Extent          Duration          Intensity      Probability      Significance   Confidence
Without                              Short- to                            Highly
                      Local                               Low                             Very Low        High
mitigation                          Medium-term                          Probable

With                                 Short- to                            Highly
                      Local                               Low                            VERY LOW         High
mitigation                          Medium-term                          Probable



5.1.2.4    Galley waste

Description of impact
Galley wastes, comprising mostly of biodegradable food waste, would place a small organic and bacterial
loading on the marine environment.

Assessment
The volume of galley waste from the seismic and support vessel would be small and comparable to
wastes from any vessel of a similar crew compliment. Discharges of galley wastes, according to Marpol
73/78 standards, would be comminuted to particle sizes smaller than 25 mm prior to disposal to the
marine environment. Such disposal would not take place within 12 nautical miles (± 22 km) from the
coast. The potential impact of galley waste disposal on the marine environment would be of low intensity
and limited to the survey area over the short-term. The potential impact of galley waste on the marine
environment is therefore considered to be of VERY LOW significance with or without mitigation (see
Table 5.5).

Mitigation
No mitigation measures are deemed necessary (assuming discharge is in compliance with the Marpol
73/78 standards).

Table 5.5:        Impact of galley waste disposal from the seismic and support vessel.

                      Extent          Duration          Intensity      Probability      Significance   Confidence
Without                              Short- to                            Highly
                      Local                               Low                             Very Low        High
mitigation                          Medium-term                          Probable

With                                 Short- to                            Highly
                      Local                               Low                            VERY LOW         High
mitigation                          Medium-term                          Probable




CCA Environmental (Pty) Ltd                               5-4                                            February 2009
                               Proposed 3D seismic survey in Block 2B, West Coast, South Africa


5.1.2.5    Solid waste

Description of impact
The disposal of solid waste comprising non-biodegradable domestic waste, packaging and operational
industrial waste into the sea could pose a hazard to marine fauna, may contain contaminant chemicals
and could end up as visual pollution at sea, on the seashore or on the seabed.

Assessment
Solid waste would be incinerated or transported ashore for disposal on land, and consequently would
have no impact on the marine environment. Hazardous waste would be disposed of by specialist waste
disposal contractors. The potential impact of the disposal of solid waste on the marine environment is
therefore NOT APPLICABLE (see Table 5.6).

Mitigation
No solid waste may be disposed to the marine environment and consequently no mitigation measures are
required.

Table 5.6:        Impact of solid waste disposal from the seismic and support vessel.

                       Extent           Duration          Intensity       Probability       Significance      Confidence
Without                               Short- to
                       Local                                 Zero           Probable       Not applicable       Medium
mitigation                           Medium-term

                                      Short- to                                               NOT
With mitigation        Local                                 Zero           Probable                            Medium
                                     Medium-term                                           APPLICABLE



5.1.3     NOISE FROM VESSEL AND HELICOPTER OPERATIONS

5.1.3.1    Noise from seismic and support vessel operations

Impact description
The noise from seismic and support vessels could result in localised disturbance of fauna (seal and
seabird colonies).

Impact assessment
Noise from seismic and support vessels is likely to be no higher than those from other small shipping
vessels in the region and is deemed a neutral impact. The potential impact of noise from support vessel
operations on marine fauna is considered to be localised, of low intensity in the short-term. The
significance of this impact is therefore assessed to be VERY LOW with and without mitigation (Table 5.7).

Mitigation measures
No measures are deemed necessary to mitigate noise impacts from support vessel operations.

Table 5.7:        Impact of noise from support vessel operations.

                      Extent          Duration          Intensity      Probability      Significance        Confidence
Without
                      Local          Short-term           Low            Probable         Very Low           Medium
mitigation

With
                      Local          Short-term           Low            Probable        VERY LOW            Medium
mitigation



CCA Environmental (Pty) Ltd                               5-5                                                 February 2009
                              Proposed 3D seismic survey in Block 2B, West Coast, South Africa


5.1.3.2    Noise from helicopter operations

Impact description
Helicopters would be utilised for crew / supply transfers between the seismic vessel and the mainland,
which could result in localised disturbance of fauna (seal and seabird colonies).

Impact assessment
Low altitude flight paths over bird breeding colonies could result in temporary abandonment of nests and
exposure of eggs and chicks leading to increased predation risk. Low altitude flight paths over seal
colonies can cause stampedes of animals to sea resulting in trampling of pups and nesting seabirds
within seal colonies. Disturbance of cetaceans by helicopter would depend on the distance and altitude of
the aircraft from the animals (particularly the angle of incidence of helicopter noise to the water surface)
and the prevailing sea conditions.

It is an offence in terms of the Seabirds and Seals Act of 1973 to wilfully disturb seals on the coast or on
offshore islands. In terms of the Marine Living Resources Act (No 18 of 1998) it is illegal for any vessel,
including aircraft, to approach to within 300 m of whales within South African waters. However,
indiscriminate or direct flying over seabird or seal colonies (or flying low level parallel to the coast) could
have a significant disturbance impact on breeding success or mortalities of juveniles. Although such
impacts would be local in the area of the colony, they may have wider ramifications over the range of
affected species and are deemed to range from low to high intensity. The significance of impact is
considered to range from low to high (see Table 5.8).

Mitigation measures
•      All flight paths must be planned to avoid seal and seabird colonies (including seal colonies at
       Kleinsee, Buchu Twins and Strandfontein Point) and must not be routed along the coast.
•      All pilots must be briefed on ecological risks associated with over flights of seabird and seal
       colonies.

If the suggested mitigation measures are implemented, this impact is expected to be VERY LOW (see
Table 5.8).

Table 5.8:        Impact of noise from helicopter operations.

                   Extent         Duration          Intensity         Probability     Significance   Confidence
Without
                   Local          Short-term        Low to High       Probable        Low to High    Medium
mitigation

With
                   Local          Short-term        Low               Probable        VERY LOW       Medium
mitigation



5.2     IMPACT OF SEISMIC NOISE ON MARINE FAUNA

5.2.1     POTENTIAL IMPACTS ON PLANKTON SPECIES

Plankton, which are species that are unable to determine their direction of travel within the water column,
comprise phytoplankton (floral plankton) and zooplankton (faunal plankton). Zooplankton includes
meroplankton (planktonic larval stages of fish and invertebrate larvae and eggs) as well as holoplankton
(species that spend their entire life-cycle as plankton).




CCA Environmental (Pty) Ltd                               5-6                                           February 2009
                               Proposed 3D seismic survey in Block 2B, West Coast, South Africa


Description of impact
Potential impacts of seismic pulses on plankton could include pathological injury and/or mortality. No
behavioural avoidance of the seismic survey area by plankton would occur. Limited indirect impacts may
arise from effects on predators or prey.

Assessment
Review of the literature suggests that mortality or injury to phytoplankton and meroplankton would occur
within metres of the firing airgun sound sources. Although no empirical information is available on the
effect of seismic noise on holoplankton, it is expected that those species that possess gas-filled bladders
(e.g. jellyfish) would be more susceptible to pathological injury, and impacts would be similar in volume to
mortality and injury arising from the turbulence of a ship’s propellers. However, fallow areas of no impact
would result from both spacing and sequence of 3D seismic survey lines and the duty cycle of airgun
firing. Such fallow areas and the patchy nature of plankton distribution within the Benguela System
suggest that the impact would be of low intensity across the survey area and duration. The significance of
impact is consequently deemed VERY LOW with or without mitigation (see Table 5.9).

Mitigation
No measures to mitigate the impacts of seismic sounds on plankton are deemed necessary or practical.

Table 5.9:        Impact of seismic noise on plankton.

                       Extent           Duration          Intensity       Probability       Significance   Confidence
Without
                       Local           Short-term               Low         Probable         Very Low       Medium
mitigation

With mitigation        Local           Short-term               Low         Probable        VERY LOW        Medium




5.2.2    POTENTIAL IMPACTS TO INVERTEBRATES (EXCLUDING CEPHALOPODS)

Description of impact
Most marine invertebrates do not possess hearing organs that perceive sound pressure, although many
have mechanoreceptors or statocyst organs that are sensitive to hydroacoustic disturbances. Potential
impacts of seismic pulses on invertebrates could include pathological injury, behavioural avoidance of
seismic survey areas, masking of environmental sounds and communication and indirect impacts due to
effects on predators or prey.

Assessment
There is little published information available on the effects of seismic surveys on invertebrate fauna or
the response of invertebrates to seismic impulses. However, the received noise at water depths of over
200 m is likely to be within the far-field range and outside of distances at which pathological injury of or
avoidance by benthic invertebrates would occur. However, limited avoidance of sounds may occur in
mobile neritic and pelagic invertebrates and is deemed to be of low intensity. The potential impact of
seismic noise on invertebrates is consequently deemed of negligible to low intensity across the survey
area and is considered to be of VERY LOW significance with and without mitigation. Impacts arising from
masking of biological or environmental sounds are UNKNOWN, but are expected to be of low intensity
due to the duty cycle of seismic surveys. Potential impacts arising from indirect effects on invertebrate
predators or prey are UNKNOWN. Impacts are summarised in Table 5.10.




CCA Environmental (Pty) Ltd                               5-7                                              February 2009
                               Proposed 3D seismic survey in Block 2B, West Coast, South Africa


Mitigation
Although measures to mitigate the potential impacts of seismic survey sounds on invertebrates are not
deemed necessary the following mitigation measures are recommended:

•       Any large mortalities of invertebrate species as a result of seismic activities should be noted and,
        where possible, seismic shooting should be adjusted. Such mortalities would be of particular
        concern where (a) commercially important species are involved, or (b) mortality events may attract
        vertebrate predator and scavenger species into the seismic area during the survey.
•       The implementation of “soft-start” procedures on initiation of seismic surveying would mitigate any
        extent of pathological injury in mobile invertebrate species.

Table 5.10:        Impact of seismic noise on invertebrates (excluding cephalopods).

                      Extent          Duration          Intensity      Probability      Significance    Confidence
Pathological injury
Without
                      Local          Short-term           Zero           Probable      Not Applicable    Medium
mitigation

With                                                                                       NOT
                      Local          Short-term           Zero           Probable                        Medium
mitigation                                                                              APPLICABLE
Behavioural avoidance
Without
                      Local          Short-term           Low            Probable         Very Low       Medium
mitigation

With
                      Local          Short-term           Low            Probable        VERY LOW        Medium
mitigation
Masking sounds and communication
Without
                      Local          Short-term           Low            Probable         Unknown        Medium
mitigation

With
                      Local          Short-term           Low            Probable        UNKNOWN         Medium
mitigation
Indirect impacts
Without
                      Local          Short-term           Low            Probable         Unknown        Medium
mitigation

With
                      Local          Short-term           Low            Probable        UNKNOWN         Medium
mitigation



5.2.3    POTENTIAL IMPACTS ON CEPHALOPODS

Description of impact
Potential impacts of seismic pulses to cephalopods could include pathological injury, behavioural
avoidance of seismic survey areas, masking of environmental sounds and communication and indirect
impacts due to effects on predators or prey.

Assessment
Although mortalities to squids from seismic surveys have been speculated, cephalopods have been
shown to alter their behaviour in response to received sounds of approximately 160 dB re 1 µPa and it is
assumed that cephalopods would evade noise levels higher than this (at estimated distances of 2 to 5
km) and consequently at greater ranges than where pathological injury would occur. The potential impact
on cephalopods through pathological injury and behavioural avoidance could consequently be of medium
to high intensity across the survey area and are consequently deemed of LOW significance with and

CCA Environmental (Pty) Ltd                               5-8                                             February 2009
                                 Proposed 3D seismic survey in Block 2B, West Coast, South Africa


without mitigation. Impacts arising from masking of biological or environmental sounds are UNKNOWN,
but are expected to be of low intensity due to the duty cycle of seismic surveys. Such localised avoidance
of seismic impulses by cephalopods has the potential to lead to indirect effects on higher predators. In
addition, there could be potential indirect impacts on cephalopod prey species. However, the significance
of such indirect effects on cephalopod predators or prey is UNKNOWN. Impacts are summarised in
Table 5.11.

Mitigation
The initiation of seismic surveying as a “soft start” for a minimum of 20 minutes would limit the potential
injury or mortality of cephalopod species. This requires that the sound source be ramped from low to full
power rather than initiated at full power, thus allowing a flight response to outside the zone of injury.

Table 5.11:        Impact of seismic noise on cephalopods.

                        Extent          Duration          Intensity      Probability      Significance   Confidence
Pathological injury
Without
                         Local         Short-term            High          Probable            Low         Medium
mitigation

With                                                      Low to
                         Local         Short-term                          Probable            LOW         Medium
mitigation                                                Medium
Behavioural avoidance
Without                                                  Medium to
                         Local         Short-term                          Probable            Low         Medium
mitigation                                                 High

With
                         Local         Short-term         Medium           Probable            LOW         Medium
mitigation
Masking sounds and communication
Without
                      Local          Short-term        Low               Probable           Unknown      Medium
mitigation

With
                         Local         Short-term            Low           Probable        UNKNOWN         Medium
mitigation
Indirect impacts
Without
                         Local         Short-term            Low           Probable         Unknown        Medium
mitigation

With
                         Local         Short-term            Low           Probable        UNKNOWN         Medium
mitigation



5.2.4    POTENTIAL IMPACTS ON FISH

The potential impact of seismic noise on fish larvae is discussed under Section 5.2.1 above and this
section discusses the impact on adult fish only.

Description of impact
A review of the available literature suggests that potential impacts of seismic pulses to fish species could
include pathological injury and mortality, behavioural avoidance of seismic survey areas, masking of
environmental sounds and communication and indirect impacts due to effects on predators or prey.




CCA Environmental (Pty) Ltd                                  5-9                                            February 2009
                              Proposed 3D seismic survey in Block 2B, West Coast, South Africa


Assessment
Pathological injury and mortality
Seismic noise is most likely to affect fish species that possess swimbladders. Given the general high
mobility of fish it is assumed that the majority of fish species would avoid seismic noise at lower levels
than where pathological injury or mortality would occur. However, possible injury or mortality could occur
on initiation of a sound source at full pressure in the vicinity of fish (at received levels of over about 180
dB re 1 µPa), or where reproductive, territorial or feeding behaviour override a flight response to seismic
survey sounds. Although the lack of avoidance shown by territorial reef fish could be of concern, as this
might expose such fish to injury-causing sound levels, this is unlikely considering the water depth in the
proposed survey area.

The potential pathological impact on fish species could be of high intensity across the local survey area.
The impact is therefore considered to be of low significance without mitigation and of VERY LOW
significance with mitigation.

Behavioural avoidance of seismic survey areas
Behavioural responses of some fish to seismic sounds have been documented at received levels of about
160 dB re 1 µPa. Both evidence of avoidance of seismic survey areas by schooling fish (of up to 30 km
and for up to five days after shooting terminated) and changes in feeding behaviours associated with
seismic noise have been documented.

The potential impact on local fish behaviour could therefore be of high intensity, but limited to the survey
area and short-term, and is consequently considered to be of LOW significance with and without
mitigation.

Masking of environmental sounds and communication
Fish deliberately produces sounds by three processes, including by stridulation (caused by friction of
adjacent skeletal components), by vibration of the swimbladder, or by rapid head movement. Chorus
sounds range across frequencies higher than the majority of produced seismic survey energy, but some
frequency overlap may occur. Masking is likely to be limited by the low duty cycle of seismic pulses

Communication and the use of environmental sounds by fish in the offshore environment off the west
coast of South Africa are unknown. However, impacts arising from masking of sounds are expected to be
of low intensity due to the duty cycle of seismic surveys (one firing every 10 to 15 seconds) in relation to
the more continuous biological noise. Such impacts would occur across the survey area in the short-term,
and are consequently considered of VERY LOW significance with and without mitigation.

Indirect impacts due to effects on predators or prey.
No effect is expected for herbivorous, planktivorous or invertebrate eating species, but there may be
some indirect effect on piscivorous species, which would depend on the diet make-up of the species
concerned. Although there is little information on the feeding success of fish (or larger predators) in
association with seismic surveys, reduced line-fish catches in association with seismic surveys have been
suggested to result from changes in feeding behaviour. The significance of this impact is UNKNOWN.

Impacts are summarised in Table 5.12.

Mitigation
It is recommended that a “soft-start” procedure of a minimum of 20 minutes’ duration be implemented
when initiating seismic surveying.




CCA Environmental (Pty) Ltd                              5-10                                    February 2009
                               Proposed 3D seismic survey in Block 2B, West Coast, South Africa


Table 5.12:        Impact of seismic noise on fish.

                      Extent          Duration          Intensity      Probability      Significance   Confidence
Pathological injury
Without
                      Local          Short-term           High           Probable            Low        Medium
mitigation

With                                                    Low to
                      Local          Short-term                          Probable        VERY LOW       Medium
mitigation                                              Medium
Behavioural avoidance
Without
                      Local          Short-term           High           Probable            Low        Medium
mitigation

With                                                    Low to
                      Local          Short-term                          Probable            LOW        Medium
mitigation                                              Medium
Masking sounds and communication
Without
                      Local          Short-term           Low          Improbable         Very Low      Medium
mitigation

With
                      Local          Short-term           Low          Improbable        VERY LOW       Medium
mitigation
Indirect impacts
Without
                      Local          Short-term         Unknown         Unknown           Unknown         Low
mitigation

With
                      Local          Short-term         Unknown         Unknown          UNKNOWN          Low
mitigation



5.2.5    POTENTIAL IMPACTS ON SEABIRDS

Description of effect
Potential impacts of seismic pulses to seabirds could include pathological injury, behavioural avoidance of
seismic survey areas, the masking of environmental sounds and communication and indirect impacts due
to effects on predators or prey.

Generally, it would be birds that rest on the water surface (non-diving) and diving birds that would be
affected by seismic noise.

Assessment
Among the marine avifauna of South African waters, it is only the diving birds or birds which rest on the
sea surface that may be affected by the underwater noise of seismic surveys. Of the diving seabirds, it is
only the flightless African penguin (Spheniscus demersus) that occurs within the proposed seismic survey
area. Although other plunge-diving bird species such as Cape gannets (Sula capensis) may show limited
avoidance of the seismic survey area.

Pathological injury and mortality
No pathological injury or mortalities impacts would occur in non-diving seabirds, as flying seabirds are
highly mobile and would be expected to flee from approaching seismic noise sources at distances well
outside of that that could cause pathological injury. The potential pathological impact on non-diving
species is considered to be of VERY LOW significance with or without mitigation.

Diving seabirds are highly mobile and would be expected to flee from approaching sound sources at
greater ranges than where pathological injury would occur, although initiation of a sound source at full
power in the vicinity of diving seabirds could result in injury. The potential for pathological impact of

CCA Environmental (Pty) Ltd                               5-11                                           February 2009
                              Proposed 3D seismic survey in Block 2B, West Coast, South Africa


seismic noise on diving bird species is considered to be of high intensity and would be limited to the
survey area. The potential pathological impact on diving species is considered to be of low significance
without mitigation and VERY LOW significance with mitigation.

Behavioural avoidance of seismic survey areas
Avoidance behaviour would only last for as long as the seismic survey continues and the behavioural
impact of seismic noise on non-diving seabirds is considered to be of VERY LOW significance with or
without the implementation of mitigation measures.

African penguins would be expected to hear seismic survey at considerable distances as they have good
hearing at low frequencies (which coincide with seismic survey sounds). The potential impact of
behavioural avoidance by diving seabirds is considered to be of medium to high intensity, but would be
limited to the survey area. The significance of the impact is therefore deemed to be LOW with and without
mitigation. Due to the lack of information the confidence rating for this assessment is low.

Masking of environmental sounds and communication
No information on underwater communication or use of underwater sound stimuli is available. The
potential impact of seismic noise on underwater communication and the use of underwater sound stimuli
by diving seabirds are not known, although masking is likely to be limited by the low duty cycle of seismic
pulses (one firing every 10 to 15 seconds). The potential impact of seismic noise on underwater
communication and use of underwater sound stimuli by diving seabirds are UNKNOWN.

Indirect impacts due to effects on predators or prey
The assessment of indirect effects of seismic surveys on diving seabirds is limited by the complexity of
trophic pathways in the marine environment and depends on the diet make-up of the bird species
concerned and the effect of seismic surveys on the diet species. No information is available on the
feeding success of seabirds in association with seismic survey noise. The feeding period prior to moulting
(in November) is critical to African penguins as birds do not feed during moulting and need to build up fat
reserves. However, both the broad ranges of mainly clupeid fish prey species (in relation to avoidance
patterns of seismic surveys of such prey species) and the distance of the development area from penguin
colonies suggest that indirect impacts would be VERY LOW with and without mitigation.

Impacts are summarised in Table 5.13 (non-diving seabirds) and 5.14 (diving seabirds).

Mitigation
•      It is recommended that all initiation of airgun firing be carried out as “soft-starts” of at least 20
       minutes duration.
•      It is recommended that an area of radius of 500 m be scanned for the presence of diving seabirds
       prior to the commencement of “soft starts” and that soft starts are delayed until such time as this
       area is clear of seabirds.
•      At all times during the survey, seabird incidence and behaviour should be recorded by an onboard
       Independent Observer or Marine Mammal Observer (MMO). Any attraction of predatory seabirds
       by mass disorientation and stunning of fish as a result of seismic survey activities, and incidents of
       feeding behaviour near the hydrophone streamer, should be recorded. If obvious mortality or
       injuries to seabirds are observed, the survey should be terminated temporarily. However, it is
       important that Observers or MMO’s have a full understanding of the financial implications of
       terminating firing, and that such decisions are made confidently and expediently. In this light it is
       suggested that Observers or MMO’s advise when surveys are to be terminated and a log of all
       termination decisions is kept (for inclusion in both daily and close out reports).




CCA Environmental (Pty) Ltd                              5-12                                    February 2009
                               Proposed 3D seismic survey in Block 2B, West Coast, South Africa


Table 5.13:        Impact of seismic noise on non-diving seabirds.

                      Extent          Duration          Intensity      Probability      Significance   Confidence
Pathological injury
Without
                      Local          Short-term           Low          Improbable         Very Low        High
mitigation

With
                      Local          Short-term           Low          Improbable        VERY LOW         High
mitigation
Behavioural avoidance
Without
                      Local          Short-term           Low          Improbable         Very Low        High
mitigation

With
                      Local          Short-term           Low          Improbable        VERY LOW         High
mitigation



Table 5.14:        Impact of seismic noise on diving seabirds.

                      Extent          Duration          Intensity      Probability      Significance   Confidence
Pathological injury
Without
                      Local          Short-term           High           Probable            Low        Medium
mitigation

With
                      Local          Short-term           Low            Probable        VERY LOW       Medium
mitigation
Behavioural avoidance
Without                                                Medium to
                      Local          Short-term                          Probable            Low          Low
mitigation                                               High

With                                                   Medium to
                      Local          Short-term                          Probable            LOW          Low
mitigation                                               High
Masking sounds and communication
Without
                      Local          Short-term         Unknown         Unknown           Unknown         Low
mitigation

With
                      Local          Short-term         Unknown         Unknown          UNKNOWN          Low
mitigation
Indirect impacts
Without                                                 Low to
                      Local          Short-term                         Unknown           Very Low        Low
mitigation                                              Medium

With
                      Local          Short-term           Low           Unknown          VERY LOW         Low
mitigation



5.2.6    POTENTIAL IMPACTS ON SEALS

Description of impact
Review of the available literature suggests that potential impacts of seismic pulses to Cape fur seals
could include pathological injury, behavioural avoidance of seismic survey areas, masking of
environmental sounds and underwater communication and indirect impacts due to effects on predators or
prey.




CCA Environmental (Pty) Ltd                               5-13                                           February 2009
                              Proposed 3D seismic survey in Block 2B, West Coast, South Africa


Assessment
One eared seal species, the Cape fur seal (Arctocephalus pusillus) is resident within the waters of the
west coast of South Africa, while several species of both eared and true seals have been recorded as
vagrants in the area. Cape fur seals are known to feed within the proposed survey area and breeding
colonies are found on the coast to the north and south of the survey area.

Pathological injury and mortality
The potential for pathological injury to seals from seismic noise is expected to be low as it is assumed
that highly mobile creatures such as fur seals would avoid severe sound sources at levels below those at
which discomfort occurs. Learned associated feeding stimuli may override the flight response and Cape
fur seals have been recorded to approach operational seismic survey gear. The potential impact of
pathological injury to seals as a result of seismic noise is therefore deemed to be of medium to high
intensity and would be limited to the survey area, although injury could extend beyond the survey
duration. The significance of impact is High to Low without mitigation and MEDIUM to LOW with
mitigation.

Behavioural avoidance of seismic survey areas
Cape fur seals appear to be relatively tolerant to loud noise pulses, especially if there is an attraction to
prey in the area. Cape fur seals have been shown to have an initial startle reaction to airgun noise, but
were not scared away from fishing gear. Cape fur seals often also approach seismic survey operations
and may even bite hydrophone streamers. This is assumed to be a learned response to the food supply
provided by towed fishing gear. The potential impact of seal behaviour in response to seismic surveys is
considered to be of VERY LOW significance with or without mitigation.

Masking of environmental sounds and communication
The fact that seals have acute underwater directional hearing suggests that sound is used in orientating
underwater. True seals have been shown to use underwater vocalisation in both orientation and
communication. The use of underwater sounds for environmental interpretation and communication by
Cape fur seals is unknown, although masking is likely to be limited by the low duty cycle of seismic pulses
(one firing every 10 to 15 seconds). The impacts of masking are considered VERY LOW with and without
mitigation.

Indirect impacts due to effects on predators or prey.
The assessment of indirect effects of seismic surveys on Cape fur seals is limited by the complexity of
trophic pathways in the marine environment and depends on the diet make-up of the species (and the
flexibility of the diet) and the effect of seismic surveys on the diet species. The broad ranges of fish prey
species (in relation to the avoidance patterns of seismic surveys of such prey species and the extended
foraging ranges of Cape fur seals) suggest that indirect impacts due to effects on predators or prey would
be VERY LOW with and without mitigation. Given the difficulty of assessing impacts on trophic pathways,
the confidence in this assessment is very low.

Impacts are summarised in Table 5.15.

Mitigation
•      The initiation of all airgun firing should be carried out as “soft-starts”.
•      It is recommended that an area of radius of 500 m be scanned for the presence of seals prior to the
       commencement of “soft starts” and that “soft starts” are delayed until such time as this area is clear
       of seals.
•      A MMO should record seal incidence and behaviour. Airgun firing should, if possible, be terminated
       temporarily if any obvious abnormal behaviour of seals in close proximity to firing airguns is
       observed. However, it is important that MMOs have a full understanding of the financial
       implications of terminating firing and that such decisions are made confidently and expediently. In

CCA Environmental (Pty) Ltd                              5-14                                    February 2009
                               Proposed 3D seismic survey in Block 2B, West Coast, South Africa


        this light it is suggested that MMOs advise when surveys are to be terminated and a log of all
        termination decisions is kept (for inclusion in both daily and close out reports).



Table 5.15:        Impact of seismic noise on seals.

                      Extent          Duration          Intensity      Probability      Significance   Confidence
Pathological injury
Without                              Short-long        Medium to
                      Local                                              Probable        High to Low    Medium
mitigation                             term              High

With                                 Short-long                                          MEDIUM TO
                      Local                             Medium           Probable                       Medium
mitigation                             term                                                LOW
Behavioural avoidance
Without                                                 Low to
                      Local          Short-term                          Probable         Very Low      Medium
mitigation                                              Medium

With                                                    Low to
                      Local          Short-term                          Probable        VERY LOW       Medium
mitigation                                              Medium
Masking sounds and communication
Without                                                 Low to
                      Local          Short-term                        Improbable         Very Low        Low
mitigation                                              Medium

With                                                    Low to
                      Local          Short-term                        Improbable        VERY LOW         Low
mitigation                                              Medium
Indirect impacts
Without
                      Local          Short-term           Low           Unknown           Very Low      Very Low
mitigation

With
                      Local          Short-term           Low           Unknown          VERY LOW       Very Low
mitigation



5.2.7    POTENTIAL IMPACT ON CETACEANS (WHALES AND DOLPHINS)

Description of impact
Review of the available literature suggests that potential impacts of seismic pulses to whales and
dolphins could include pathological injury, behavioural avoidance of seismic survey areas, masking of
environmental sounds and communication, and indirect impacts due to effects on predators or prey.

Assessment
At present between 24 and 32 cetacean species are recorded off the West Coast of South Africa or are
expected to be found in the region based on their distribution elsewhere along the west coast of southern
Africa. The range in the number of species reflects taxonomic uncertainty at species and sub-species
level, rather than uncertainty of occurrence or distribution patterns. The majority of migratory cetaceans in
southern African waters are baleen whales (mysticetes), while toothed whales (odontocetes) may be
resident or migratory. The populations of large baleen whales in southern African waters were decimated
by historical whaling and are currently at a fraction of their pre-exploitation levels.

Marked differences occur in the hearing of baleen whales (mysticete cetaceans) and toothed whales and
dolphins (odontocete cetaceans), with baleen whale hearing centred at below 1 kHz, while toothed whale
and dolphin hearing is centred at frequencies of between 10 and 100 kHz.




CCA Environmental (Pty) Ltd                               5-15                                           February 2009
                              Proposed 3D seismic survey in Block 2B, West Coast, South Africa


The majority of migratory baleen whales (blue, fin, sei, minke and Bryde’s whales) would occur within the
offshore waters of the West Coast over the May to November period, while minke whales are also
expected within the nearshore environment over this period. Southern right and humpback whales are
expected within the extreme nearshore environment over this period, while humpback whales are
expected over the shelf water survey region in both winter and summer, while the locally resident Bryde’s
whales may possibly occur in the survey region.

Three odontocete species (killer whales, dusky dolphin and Heaviside’s dolphin) are found within the
survey area and two further species (southern right whale dolphin and Risso’s dolphin) may possibly be
found in the survey area.

Pathological injury and mortality
Pathological injury to cetaceans (migratory baleen whale species and toothed whales and dolphins) can
result from exposure to high sound levels through a number of avenues, including trauma to both auditory
and non-auditory tissues as shifts of hearing threshold (as permanent (PTS) or temporary threshold shifts
(TTS)); direct tissue damage (arising from the near instantaneous increase in pressure such as that which
forms the shock waves of explosive pulses, and which do not occur in seismic survey pulses);
acoustically induced decompression sickness or other non-auditory physiological effects. The probability
of trauma to non-auditory tissues is deemed to be lower, particularly with recommended mitigation
measures, while the probability of acoustically induced “decompression sickness” like trauma is believed
to be very low in baleen whales.

There is little information available on the levels of noise that would potentially result in pathological injury
to whales and dolphins. Received levels of 180 dB are quoted throughout the literature (see Compton et
al., 2008) as the threshold level above which acoustically induced trauma may occur in marine mammals.
Assuming a 20 dB horizontal spreading loss and a spherical spreading model, received levels of 180 dB
would be received at a distance of approximately 1000 m from a 260 dB re 1µPa at 1 m source pulse. No
PTS have been recorded in cetaceans. TTS have been induced in captive dolphin species at received
levels of over 190 dB, although it should be noted that the limited duration of seismic survey pulses would
limit the onset of TTS to far higher levels (for example, no TTS were recorded in a captive bottlenose
dolphin exposed to 229 dB pulses from a watergun). Such information suggests that cetaceans would
need to be in close vicinity to operating airguns to receive injury (McCauley (1994) suggested within 50
m), and it is assumed that highly mobile species such as cetaceans would avoid sound sources at
distances well outside those where injury would occur (see behaviour avoidance below). Such injury
could occur if firing was initiated at full power in close vicinity to animals.

Deep diving cetacean species may be more susceptible to acoustic injury, particularly in the case of
seafloor-focussed seismic surveys, where the downward focussed impulses could trap deep-diving
cetaceans within the survey pulse, as escaping towards the surface would result in exposure to higher
sound level pulses. There is increasing evidence of odontocete stranding incidents (particularly amongst
the deep-diving beaked whales) associated with anthropogenic acoustic activities; particularly mid-
frequency sonar pulses. Stranding case studies indicate that both fatal non-auditory trauma and
behavioural disorientation may result from high-level acoustic impulses. Although seismic and mid-
frequency sonar pulses differ considerably in frequencies and their duty cycles, seismic surveys have
been implicated in odontocete stranding events.

The impact of potential pathological injury to cetaceans as a result of high-amplitude seismic sounds is
deemed to be of high intensity, but would be limited to the vicinity of the operating airguns within the
survey areas. The impacts of injury may continue after the duration of the surveys and could extend into
the long term. The significance of this impact for both mysticete and odontocete cetaceans is by
definition considered to be low to high with or without mitigation measures.


CCA Environmental (Pty) Ltd                              5-16                                       February 2009
                              Proposed 3D seismic survey in Block 2B, West Coast, South Africa


Behavioural avoidance of seismic survey areas
There is a considerable body of evidence on the avoidance of seismic surveys by cetaceans, particularly
mysticete species. Such published literature suggests that avoidance starts at distances where levels of
approximately 150 to 180 dB are received. More subtle alterations in behaviour may occur at received
levels of 120 dB. Although behavioural avoidance of seismic noise by baleen whales is highly likely, such
avoidance is probably of minimal impact in relation to the distances of migrations of the majority of baleen
whale species.

The majority of baleen whales migrate from the Antarctic waters to the southern African subcontinent to
breed. The impact on breeding species within mating, calving and nursing areas or seasons (or on
species within feeding grounds) would be higher than on non-breeding/non-feeding or migratory species.
Therefore avoidance of critical breeding habitat or areas where mating, calving or nursing occurs is of
greater concern. Although the migration paths of offshore baleen whale species lie offshore of the
proposed survey areas, southern right whales and humpback whales may feed over the shelf throughout
the summer (at minimum within the early summer months), while southern right whales may be using the
extreme nearshore region as a calving and nursery area in the winter and spring period.

As the survey is proposed for the first quarter of 2010, i.e. outside of the winter/spring migration of
mysticetes, the potential impact of behavioural avoidance of seismic survey areas by mysticete cetaceans
is considered to be of medium to high intensity, local to regional extent and for the short duration of the
survey. The significance of impact is deemed low to medium with and without mitigation.

The available information on the responses of toothed whales and dolphins to seismic surveys is more
limited than that for baleen whales. There is less evidence of avoidance of seismic surveys by toothed
whales (including dolphins) than for baleen whales, and the impact of seismic survey noise on the
behaviour of toothed whales is deemed to be of high to medium intensity over the survey area and for the
duration of the survey. The significance of impact may vary by odontocete species and consequently
ranges from LOW to VERY LOW. No appropriate operational measures to mitigate avoidance behaviour
by odontocete cetaceans could be recommended. However, the confidence in this assessment is lower
than that for mysticete cetaceans given the lack of available data.

Masking of environmental sounds and cetacean communication
Baleen whales appear to vocalise exclusively within the frequency range of the maximum energy of
seismic survey noise, while toothed whales (which includes dolphins) vocalise at frequencies higher than
these. Humpback whales may be singing during their southward migration through the region between
September and November. However, masking is likely to be limited by the low duty cycle of seismic
pulses (one firing impulse every 10 to 15 seconds). The available literature suggest that masking of
dolphin communication sounds would only occur within limited range of the seismic source. The intensity
of impact is likely to be low over the survey areas and duration, and the significance is deemed VERY
LOW for mysticete and odontocete cetaceans. No appropriate operational mitigation measures could be
recommended.

Indirect impacts due to effects on predators or prey
The majority of baleen whales would undertake little feeding within breeding ground waters and rely on
blubber reserves for the migrations from the feeding grounds. However, there is recent evidence that the
Benguela Upwelling System may be utilised as a low latitude feeding ground by humpback whales during
summer. Although fish prey have been recorded from the stomachs of humpbacks off the Cape coast,
euphausiid plankton prey may also be important in the diet. It is possible that feeding takes place in the
region of the proposed seismic surveys, although indirect impacts through effects on prey species
remains unknown.




CCA Environmental (Pty) Ltd                              5-17                                    February 2009
                              Proposed 3D seismic survey in Block 2B, West Coast, South Africa


The lack of feeding by the majority of migratory baleen whales species within the proposed seismic
survey areas suggest that indirect impacts due to effects on prey would be very low. The impacts on
feeding of southern right and humpback whales remain largely unknown, but is estimated to be of
medium to high intensity, local and short-term duration and consequently of low to very low significance.

It is expected that both fish and cephalopod prey of toothed whales and dolphins may be affected over
limited areas. As with other vertebrates, the assessment of indirect effects of seismic surveys on resident
odontocete cetaceans is limited by the complexity of trophic pathways in the marine environment. The
impacts are difficult to determine, and would depend on the diet make-up of the species (and their
flexibility in their diet), and the effect of seismic surveys on the diet species.

The broad distribution ranges of both cetacean and their prey species in relation to the avoidance
patterns of prey species suggest that even with a high intensity, local extent and short duration of each
survey, indirect impacts due to effects on prey would be of low significance for odontocete cetaceans.
The confidence in this assessment remains very low.



Mitigation
•    Seismic surveys should as far as possible be planned to coincide with the movement of migratory
     cetaceans out of South African waters, i.e. between January and May, when the majority of migratory
     baleen whales are on their southern feeding grounds.

•    It is recommended that all initiations of seismic surveying be carried out as “soft-starts” for a
     minimum of 20 minutes. This requires that the sound source be ramped from low to full power rather
     than initiated at full power, thus allowing a flight response to outside the zone of injury or avoidance.
     The rational for the 20 minute “soft-start” period is based on the speeds of flight of cetacean species.
     It is further recommended that initiation of firing is only to begin after observations by MMO’s have
     deemed the visual area around the vessel to a distance of 1 000 m is clear of all marine mammal
     species for at least 30 minutes prior to firing, so that deep or long diving species can be detected.

•    It is recommended that dedicated MMO’s are used and that MMO’s are not burdened with fisheries
     monitoring tasks. However, if this is not possible, daylight hours should be used for observation and
     daily reports should only be compiled outside MMO observation periods.

•    MMO’s should be placed on board the seismic vessel to carry out daylight observations (where
     possible) of the seismic survey areas and record responses of penguins and marine mammals to
     seismic shooting, including distance from the vessels, swimming speed and direction and obvious
     changes in behaviour (for example, obvious alteration in behaviour such as resting to flight or surface
     active to diving). Both the identification and the behaviour of the animals must be recorded accurately
     along with current noise levels. MMO’s should, where possible, have experience in seabird and
     marine mammal identification and observation techniques.

•    MMO’s should record incidence of feeding behaviour of predators near the hydrophone streamer.
     Mass disorientation and stunning of fish by seismic surveys is unlikely, although if occurs, may result
     in attraction of predatory seabirds and mammals.

•    Seismic shooting should be terminated when obvious changes to seal or cetacean behaviours are
     observed from the survey vessel, or cetaceans are observed within the 500 m of operating airguns.
     The rationale for this being that animals at such distances (where pathological injury may occur) may
     be suffering from reduced hearing as a result of seismic sounds, that frequencies of seismic sound
     energy lies below best hearing frequencies (certain toothed cetaceans and seals), or that animals
     have become trapped within the ensonified area through their diving behaviour. However, it is

CCA Environmental (Pty) Ltd                              5-18                                    February 2009
                               Proposed 3D seismic survey in Block 2B, West Coast, South Africa


     important that MMO’s have a full understanding of the financial implications of terminating firing, and
     that such decisions are made confidently and expediently. In this light it is suggested that MMO’s
     advise when surveys are to be terminated and a log of all termination decisions is kept (for inclusion
     in both daily and close out reports).

•    All data recorded by MMO’s should at minimum form part of a survey close–out report. Furthermore,
     daily or weekly reports should be forwarded to the necessary authorities to ensure compliance with
     the mitigation measures.

•    It is recommended that seabird and marine mammal incidence data and seismic source output data
     (observer reports and close-out reports) arising from surveys should be made available at request for
     future analyses of survey impacts in local waters. It is also recommended that any marine mammal
     biologists working within the region of the survey be informed of the duration and location of the
     survey so that any possible stranding events coincident with the seismic survey can be evaluated for
     evidence of acoustically induced auditory and non-auditory traumas. The UK Department of Trade
     and Industry has suggested Passive Acoustic Monitoring (PAM) as a mitigation measure for seismic
     surveys. Such PAM detects animals through their vocalisations. Where possible the use of PAM of
     marine mammal sounds in the vicinity of the survey vessel should be investigated, particularly if such
     monitoring can provide distance and bearing of the animals from the survey vessel. However, it
     should be noted that despite being suggested some years ago, PAM does not appear to be readily
     available to seismic contactors.

Table 5.16:        Impact of seismic noise on mysticete cetaceans.

                      Extent          Duration          Intensity      Probability      Significance   Confidence
Pathological injury
Without                             Short-term –
                      Local                               High           Probable        Low to High    Medium
mitigation                           Long-term
With                                Short-term –
                      Local                               High           Probable      LOW TO HIGH      Medium
mitigation                           Long-term
Behavioural avoidance
Without                                                Medium to                           Low to
                      Local          Short-term                          Probable                       Medium
mitigation                                               High                              Medium
With                                                   Medium to                           LOW TO
                      Local          Short-term                          Probable                       Medium
mitigation                                               High                              MEDIUM
Masking sounds and communication
Without
                      Local          Short-term           Low            Probable         Very Low      Medium
mitigation
With
                      Local          Short-term           Low            Probable        VERY LOW       Medium
mitigation
Indirect impacts
Without
                      Local          Short-term           Low            Probable         Very Low      Very Low
mitigation
With
                      Local          Short-term           Low            Probable        VERY LOW       Very Low
mitigation



The two resident neritic cetacean species which occur within the inshore waters of the survey region are
the Heaviside’s dolphin and the dusky dolphin. The ranges of both species will overlap with the proposed
seismic survey and impacts (including injury, behavioural avoidance, masking and indirect effects) are
deemed likely.


CCA Environmental (Pty) Ltd                               5-19                                           February 2009
                               Proposed 3D seismic survey in Block 2B, West Coast, South Africa


Table 5.17:        Impact of seismic noise on odontocete cetaceans.

                      Extent          Duration          Intensity      Probability      Significance   Confidence
Pathological injury
Without                             Short-term –
                      Local                               High           Probable        Low to High    Medium
mitigation                           Long-term
With                                Short-term –
                      Local                               High           Probable      LOW TO HIGH      Medium
mitigation                           Long-term
Behavioural avoidance
Without                                                Medium to                         Very Low to
                      Local          Short-term                          Probable                         Low
mitigation                                               High                               Low
With                                                   Medium to                       VERY LOW TO
                      Local          Short-term                          Probable                         Low
mitigation                                               High                             LOW
Masking sounds and communication
Without
                      Local          Short-term           Low            Probable         Very Low      Medium
mitigation
With
                      Local          Short-term           Low            Probable        VERY LOW       Medium
mitigation
Indirect impacts
Without
                      Local          Short-term           Low            Probable            Low        Very Low
mitigation
With
                      Local          Short-term           Low            Probable            LOW        Very Low
mitigation



5.3     IMPACT ON OTHER USERS OF THE SEA

5.3.1    POTENTIAL IMPACT ON FISHING INDUSTRY

Description of impact
The proposed seismic survey could result in impacts on fishing as a result of the 500 m safety zones
around the vessel (in terms of the Marine Traffic Act (No. 2 of 1981)). In addition to the statutory 500 m
safety zone, a seismic contractor would request a safe operational limit (that is greater than the 500 m
safety zone) that it would like other vessels to stay beyond. Typical safe operational limits for a 3D survey
are illustrated in Figure 3.4. QVD would commission a support / chase vessel equipped with appropriate
radar and communications to patrol the area during the seismic survey to ensure that other vessels
adhere to the safe operational limits.

Impacts could include the loss-of-access to fishing grounds during the survey period, disruption to fishing
activities and subsequent loss of catch (i.e. economic loss) in the proposed survey area.

The fishing sectors that could potentially be impacted by the proposed safety zone include demersal
trawling, demersal longlining, large pelagic longlining and Tuna pole / traditional fishing.

Assessment
Demersal trawl sector
The demersal trawl sector (i.e. trawling for fish on the sea floor) on the West Coast focuses on a broad
area along the shelf edge from about 300 m to 800 m. Trawling activity is not expected in the vicinity of
the survey area as trawl grounds lie well to the south and west of the proposed survey area (see Figure
4.16 in Chapter 4). However, it should be noted that any unexpected interactions with trawler gear and
vessels could result in serious damage to the towed seismic array.


CCA Environmental (Pty) Ltd                               5-20                                           February 2009
                              Proposed 3D seismic survey in Block 2B, West Coast, South Africa


The impact on the demersal trawl sector is considered to be localised, of low intensity in the short-term.
The significance of this impact is therefore assessed to be VERY LOW with and without mitigation (Table
5.18).

Demersal longlining sector
On the West Coast demersal longliners operate in well-defined areas extending along the shelf break
from Port Nolloth to Cape Agulhas where they may be expected to operate in water depths between 150
and 750 m. However, the majority of effort is directed between depths of 200 m and 650 m with a strong
peak at 400 m. The areas of operation lie well to the west of the proposed survey area (see Figure 4.20 in
Chapter 4). However, the possibility of encountering demersal longline gear or vessels in the proposed
survey area, although unlikely, cannot be entirely excluded.

The impact on the demersal longlining sector is considered to be localised, of low intensity in the short-
term. The significance of this impact is therefore assessed to be VERY LOW with and without mitigation
(Table 5.18).

Large pelagic longlining
Longlining for tuna and shark is mostly directed at the shelf edge and beyond the South African Exclusive
Economic Zone and activity does not occur shallower than 400 m water depth. Although there is no
anticipated interaction between this fishery and the proposed seismic survey (Figure 4.22 in Chapter 4), it
cannot be entirely excluded.

The impact on the large pelagic longlining sector is considered to be localised, of low intensity in the
short-term. The significance of this impact is therefore assessed to be VERY LOW with and without
mitigation (Table 5.18).

Tuna pole / traditional fishing
The proposed survey area is not specifically targeted by the linefish fishery although there are minimal
reported catches in the area (mostly October to March). Therefore, although the possibility of
encountering line vessels in the area is unlikely, it should not be excluded. This type of fishing does not
deploy any restrictive gear and vessels may easily move out of the survey path or into other areas.

The impact on the Tuna pole / traditional fishing longlining sector is considered to be localised, of low
intensity in the short-term. The significance of this impact is therefore assessed to be VERY LOW with
and without mitigation (Table 5.18).

Mitigation
•      The setting up of communication channels between the fishing industry, the Department of
       Environmental Affairs and Tourism (DEAT) and interested and affected parties is essential. This
       would involve pre-survey notification and regular updates on the survey progress via email. Fishing
       industry bodies should include; the South African Deep-Sea Trawling Industry Association
       (SADSTIA), SA Inshore (small pelagic industry), the Shark Longline Association, Small Hake
       Association, South African Tuna Longline Association (SATLA), Fresh Tuna Exporters Association
       (FTEA) and the West Coast Rock Lobster Association (WCRLA). Interested and affected parties
       should include; FAMDA, PetroSA, the naval hydrographic office and De Beer’s Marine.
•      An experienced onboard Independent Observer should also provide a fisheries facilitation role to
       identify and communicate with fishing vessels in the area to reduce the risk of gear interaction
       between fishing and seismic survey activities. The Observer should be familiar with fisheries
       operational in the area and with environmental monitoring protocols relating specifically to marine
       mammals, birds and other fauna. The Observer should report daily on vessel activity and respond
       and advise on action to be taken in the event of encountering fishing gear and the survey vessel’s
       potential impacts on marine fauna.



CCA Environmental (Pty) Ltd                              5-21                                    February 2009
                                  Proposed 3D seismic survey in Block 2B, West Coast, South Africa


Table 5.18:        Assessment of the potential impact relating to increased fishing effort and
                   disruption to fishing activities.

                      Extent             Duration          Intensity      Probability      Significance   Confidence
Demersal trawl
Without
                       Local            Short-term           Low          Improbable         Very Low        High
mitigation

With
                       Local            Short-term           Low          Improbable        VERY LOW         High
mitigation
Demersal longlining
Without
                       Local            Short-term           Low          Improbable         Very Low        High
mitigation

With
                       Local            Short-term           Low          Improbable        VERY LOW         High
mitigation
Large pelagic longlining
Without
                       Local            Short-term           Low          Improbable         Very Low        High
mitigation

With
                       Local            Short-term           Low          Improbable        VERY LOW         High
mitigation
Tuna pole / traditional fishing
Without
                       Local            Short-term           Low          Improbable         Very Low        High
mitigation

With
                       Local            Short-term           Low          Improbable        VERY LOW         High
mitigation



5.3.2    POTENTIAL IMPACT ON MARINE MINING

Description of impact
Diamond mining and associated activities (e.g. prospecting and refuelling) would be required to avoid the
500 m safety zone and proposed safe operational limits (i.e. 8 km fore and aft of the vessel and 6 km
abeam during daylight, and 12 km fore and aft and 9 km abeam during the night) around the seismic
vessel, which could cause a disruption to diamond mining and associated activities.

Assessment
The proposed survey area falls in one of De Beers Consolidates Mines’ licence areas (Figure 4.27 in
Chapter 4). Although the proposed survey area is located outside of De Beers’ current mining area it is
located within an area where refuelling generally takes place and where prospecting is planned for the
last quarter of 2009 and first quarter of 2010.

The potential impact of the proposed seismic survey on diamond mining is considered to be localised, of
low intensity in the short-term. The significance of this impact is therefore assessed to be VERY LOW
with and without mitigation (Table 5.19). The potential impact on associated activities (e.g. prospecting
and refuelling) is considered to be localised, of medium intensity in the short-term. The significance of this
impact is therefore assessed to be LOW TO MEDIUM without mitigation (Table 5.19).

Mitigation
Discussion must take place with De Beers Marine during the detailed planning phase in order to confirm
the exact co-ordinates and to discuss the scheduling of the proposed seismic survey in relation to mining


CCA Environmental (Pty) Ltd                                  5-22                                           February 2009
                               Proposed 3D seismic survey in Block 2B, West Coast, South Africa


and prospecting activities being undertaken by De Beers Marine. This would ensure that De Beers Marine
is able to reschedule (if necessary) or relocate their refuelling and prospecting location.

The potential impact on associated activities is considered to be of VERY LOW significance after
mitigation (Table 5.19).

Table 5.19:       Assessment of impact on diamond mining.

                      Extent          Duration          Intensity      Probability      Significance   Confidence
Diamond mining
Without
                      Local          Short-term            Zero          Probable         Very Low        High
mitigation

With
                      Local          Short-term            Zero          Probable        VERY LOW         High
mitigation
Associated activities (e.g. prospecting and refuelling)
Without                                                                                    Low to
                      Local          Short-term           Medium         Probable                         High
mitigation                                                                                 Medium

With
                      Local          Short-term            Zero          Probable        VERY LOW         High
mitigation



5.3.3    POTENTIAL IMPACT ON MARINE TRANSPORT ROUTES

Description of impact
The presence of the seismic vessel with the associated 500 m safety zone and proposed safe operational
limits could interfere with shipping in the area.

Assessment
The majority of shipping traffic is located on the outer edge of the continental shelf, which is located to the
west of the proposed survey area. The inshore traffic of the continental shelf along the West Coast is
largely comprised of fishing and mining vessels, especially between Kleinsee and Oranjemund (Figure
4.24 in Chapter 4).

Although the safety zone around the seismic vessel would be relatively small all vessels would be
prohibited from entering this area. The impact on shipping traffic in the proposed seismic survey area is
considered to be localised, of low intensity in the short-term. The significance of this impact is therefore
assessed to be VERY LOW with and without mitigation (Table 5.20).

Mitigation
•      Prior to the commencement of activities, QVD and its contractors must notify relevant bodies
       including: the Department of Minerals and Energy (DME), PASA, South African Maritime Safety
       Authority (SAMSA), the South African Navy Hydrographic Office, relevant Port Captains, DEAT:
       Marine and Coastal Management, PetroSA, Forest Oil and De Beers Marine. These bodies must
       be notified of the navigational co-ordinates of any location prior to commencement of such
       activities.
•      The seismic and support vessel must be certified for seaworthiness through an appropriate
       internationally recognised marine certification programme (e.g. Lloyds Register, Det Norske
       Veritas). The certification, as well as existing safety standards, requires that safety precautions
       would be taken to minimise the possibility of an offshore accident. Collision prevention equipment
       should include radar, multi-frequency radio, foghorns, etc. Additional precautions include: the
       support / chase vessel, the existence of an internationally agreed 500 m safety zone around the

CCA Environmental (Pty) Ltd                                5-23                                          February 2009
                               Proposed 3D seismic survey in Block 2B, West Coast, South Africa


       seismic vessel, cautionary notices to mariners, and access to current weather service information.
       The vessels must be fully illuminated during twilight and night. The law also requires equipment
       and training to ensure the safety and survival of the crew in the event of an accident.
•      A Notice to Mariners should provide:
       ⇒     the co-ordinates of the proposed survey area;
       ⇒     an indication of the proposed survey timeframes and day-to-day location of the seismic
             vessel; and
       ⇒     an indication of the 500 m safety zones and the proposed safe operational limits of the
             survey vessel.

Table 5.20:       Assessment of interference with marine transport routes and recreational facilities.

                      Extent          Duration          Intensity      Probability      Significance   Confidence
Without
                      Local          Short-term           Low            Probable         Very Low      Medium
mitigation

With
                      Local          Short-term           Low          Improbable        VERY LOW       Medium
mitigation




CCA Environmental (Pty) Ltd                               5-24                                           February 2009

								
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