Stakeholder Update 4 September 2018

Transcription

1 Gippsland Marine Seismic Survey Stakeholder Update 4 September 2018 Introduction CGG Services (Australia) Pty Ltd (CGG) is proposing a three dimensional (3D) marine seismic survey (MSS) in the Gippsland Basin. The Gippsland MSS would operate over approximately 16,850 km2 including approximately 14,100 km2 where seismic data would be acquired. The survey vessels (primary and secondary seismic vessels, support and chase vessels) will be at least 12 km offshore in Commonwealth waters. Two seismic vessels would work together for undershooting ; surveying the geology underneath the existing petroleum platforms. Undershooting would not require more frequent seismic pulses but would require the lines to be closer together to maintain data quality. Water depths within the survey area range from a minimum of 34 m along Ninety Mile Beach to a maximum of 2676 m in the Bass Canyon. The spatial extent of the area in which seismic data will be acquired (the Acquisition Area ) and additional area required for turning the seismic vessel (the Operational Area ) are shown in Figure 1. The survey is intended to commence in November / December 2018 and run for approximately 6.5 months. Since May this year CGG has been undertaking consultation to inform and gain feedback from stakeholders whose functions, interests or activities may be affected by the proposed MSS. The purpose of this letter is to update relevant stakeholders on revised survey strategies, based on stakeholder feedback and updated underwater sound modelling, that aim to minimise impacts to stakeholders such as commercial fishers. Figure 1: The Gippsland MSS Acquisition and Operational Areas Showing Survey Zones and Undershooting Locations

2 Why is this survey needed The Gippsland marine seismic survey is a typical 3D survey similar to the majority of seismic surveys conducted in Australian marine waters in terms of technical methods and procedures. While there have been seismic surveys in the Gippsland Basin over the last ~50 years, this survey has been proposed because CGG has identified a number of issues with previous surveys that prevent a comprehensive regional geological evaluation of the Gippsland Basin. This survey is intended to resolve these issues by achieving a basin-wide coverage of seismic data to accurately map the extent of geological structures within the basin with confidence. Discovery of further hydrocarbon reserves could extend the working life of the existing petroleum industry in the region. Further details of the proposed survey have been described in previous correspondence and are available at CGG s website ( Effects of seismic surveys Consultation carried out to date with relevant stakeholders for the Gippsland MSS has identified specific concerns over the impacts of seismic activities on commercial fisheries which are widely held in the local fishing industry and amongst other interested parties. These concerns can be summarised into three key areas: loss of access to fishing grounds (displacement) impacts of seismic sound on the health and reproduction of commercially fished species, or on the planktonic eggs and larvae of commercially important species uncertainty in the effects of seismic sound on fish. A review of these potential impacts, the impact assessment which CGG has conducted and the associated controls to minimise them are provided in the following sections. Displacement of other marine users Fishing industry stakeholders have identified concern over the loss of access to fishing grounds throughout the survey and interference with fishing gear (e.g. entanglement). The seismic vessel will be towing long streamers bearing hydrophones for recording seismic data and will have restricted ability to manoeuvre on the water. It must stick to pre-determined sail-lines to create a reliable seismic dataset and enable assessment of the regional geology. For this reason, other vessels on the water will need to take evasive action to avoid the seismic vessel; however, no vessels will be excluded from the whole area for the duration of the survey. CGG has considered the feedback from stakeholders to date and devised a zoning scheme breaking the survey area into smaller blocks where other users will only be excluded for a short period. This will enable fishers and other marine users to plan their activities around the location and forward plans of the seismic vessel. No long-term displacement or significant disruption to fishing activities is expected because the Acquisition Area has been divided into 7 zones (Figure 1) and the seismic vessels will only be in any zone for a maximum of one month at a time. During the month each of these zones is being surveyed, the broader area will remain completely open to fishing and other activities. The timing of the acquisition within each zone will be determined by weather, avoidance of whales (if necessary), petroleum activities and avoiding impacts to fish spawning in key areas. Zone 1 will be acquired in November-December to avoid interfering with migrating humpback whales. Zone 5, encompassing Southeast Reef which was identified as an important fishing and spawning area, will be surveyed in March-April when fish spawning is at its lowest for most species. The other zones will be surveyed as appropriate to meet survey efficiency objectives and to cooperate with petroleum facility activities. Relevant fishers will be kept informed of survey activities so that their fishing operations can be planned to avoid the area in which the survey vessels are active. A Notice to Mariners will provide official notification of

3 the exclusion zones. Pre-survey notifications will commence four weeks prior to the start of the survey so that fishers have time to remove fishing gear, with ongoing communication happening 7 to 10 days prior to the survey ( look aheads ) and daily updates during the survey period. Impacts of seismic sound The dominant source of underwater noise during the Gippsland MSS will be from the operation of the seismic source (airgun array), which is proposed to be in frequent operation for the duration of the survey. The source will have a maximum volume of 3000 cubic inch (in3) which is smaller than the seismic survey sources used in many other surveys. During the proposed activity, the seismic survey vessel will traverse a series of predetermined sail lines within the Acquisition Area at a speed of approximately 4.5 to 5 knots (8 to 9.3 km/hr). Seismic data will be acquired in water depths of 35 to 2650 m. The seismic array is highly directional; focussing sound energy towards the seabed, but will also ensonify the surrounding water column to a lesser extent. The underwater sound generated by the array will be strongest at the source and rapidly decrease with distance from the source. Marine biota in the area of ensonification will be exposed to different received levels of sound energy, depending on their behaviour, physiology and where they are in relation to the source. However, actual nearfield and far-field received sound levels are influenced by a number of factors including the overall size (volume) of the acoustic source, the array configuration, water depths in the area, position in the water column, distance from the source and geoacoustic properties of the seabed. CGG carried out underwater sound propagation modelling for the sound generated by the seismic source within the Gippsland MSS Acquisition Area, to enable prediction of the spatial extent of the underwater sound impacts on marine fauna. The modelling and impact assessment used highly conservative assumptions around the predicted levels of noise and also the extent of environmental effects from the sound pulses. CGG also comprehensively analysed historic underwater sound data from the Gippsland Basin to cross-calibrate the model and ensure it reflects the real situation in this area. Details of the underwater sound modelling and impact assessment are provided below in Appendix 1. The impacts to marine fauna were based on widely accepted threshold levels, exposure levels or criteria for impacts; in line with international practice in assessing underwater sound impacts. Impacts to invertebrates (including bivalves and cephalopods) The underwater sound modelling was used to predict the area over which impacts to marine invertebrates may occur and included the area along the borders of the Acquisition Area where sound would extend beyond that area. For invertebrate species, the largest area of effect was based on the potential for a range of sub-lethal effects to occur as reported by Day et al. (2016, 2017), ranging from physiological to behavioural disturbance effects. The modelled distances from the vessel at which invertebrates may be affected by the seismic sound are shown in Table 1. Table 1: Modelled Impact Ranges for Invertebrates Invertebrate Group Species Exposure Level Reference Predicted Maximum Impact Distance Shallow water Midwater (<200 m) ( m) Crustaceans Rock lobsters 209 db re 1µPa (Lpk-pk) 92 m 160 m Prawns Sub-lethal effects Day et al. (2016) Bivalves Scallops 191 db re 1µPa (Lpk-pk) Sub-lethal effects Day et al. (2016) Cephalopods Squid, octopus 162 db re 1µPa 2.s (SEL) Behavioural effects McCauley and Fewtrell (2012) 625 m Species does not occur 1.4 km 2.2 km

4 Impacts of the Gippsland MSS on southern rock lobster and prawns are expected to be minor. For benthic adults potential effects will be limited to temporary effects in small areas (<100 m) directly under the source in areas associated with reefs or outcroppings, where depths are less than the maximum depth limit of 200 m for these species. Impacts of the proposed survey on scallops are also expected to be minor and limited to short-term effects within 625 m of the seismic source. Commercial scallops are mainly found at depths of m but may also occur down to 60 m. The main scallop grounds are in less than the minimum depth of the survey area (34 m) and are mainly to the south of the operational area. There are no known areas of importance for scallops within the Acquisition Area, and a very low level of commercial fishing effort within the Gippsland Basin. No mortality of scallops or lobsters are predicted as a result of exposure to single pulses of seismic sound; however, Day et al. (2016) observed that it is possible that repeated seismic exposure could cause physiological damage leading to mortality during undershooting. Repeated exposure during normal survey operations is unlikely given that adjacent lines will generally be acquired more than 24 hours apart and biota can recover between exposures which will diminish as the vessel moves to further lines. CGG has also revised survey plans to avoid intensive undershooting activities in the vicinity of South East Reef, which is expected to be important lobster habitat. Impacts on squid and octopus are predicted to be limited to behavioural disturbance up to 1.4 km (in <200 m water depth) and up to 2.2 km (in 200 to 1000 m depth) from the seismic source. Squid and octopus within the Acquisition Area are expected to be predominantly found in depths of <200 m; however, can occur down to 825 m. The area of ensonification for these species could therefore extend a distance of 1.4 km from the boundary of the Acquisition Area in the inshore direction and 2.2 km from the 825 m depth contour in the offshore direction. This however, is an over-estimation of the extent of behavioural disturbance effects as the whole of this area will not be permanently ensonified for the whole duration of the survey and animals avoiding the seismic sound can return to areas previously acquired, or not yet acquired. Squid and octopus exposed to received sound levels eliciting a behavioural response will recover between sail lines and no long-term effects are predicted. For planktonic stages of commercial invertebrates, exposure to the seismic sound would be transient as the vessel will be constantly moving and the plankton is constantly moving under the influence of oceanographical processes. Planktonic assemblages are very widely spread at sea and localised impacts on their populations are expected to be very localised and short-term, with negligible population level effects compared to the natural high rates of planktonic turnover. Impacts to fish (including sharks) The effects of underwater noise on fish within the vicinity of the Gippsland MSS may be either physiological injury (no fish mortality is expected) or behavioural disturbance. Behavioural changes are expected to be localised and temporary, with displacement of pelagic or migratory fish likely to have insignificant repercussions at a population level. The ANSI-Accredited Standards Committee S3/SC 1, Animal Bioacoustics Working Group (Popper et al. 2014) gathered relevant scientific experts and regulators to define acoustic impact guidelines for fish. Popper et al. (2014) cite studies on seismic sound effects on fish and confirm that no studies have linked mortality of fish, with or without swim bladders, to seismic noise from airguns or in experimental studies replicating seismic sound fields (Popper et al. 2005; Boeger et al. 2006; Popper et al. 2007; Hastings et al. 2008; Halvorsen et al. 2011, 2012; Casper et al. 2012; McCauley and Kent 2012; Miller and Cripps 2013; Popper et al. 2015). Empirical evidence comes from a study by Wagner et al. (2015) which exposed gobies to seismic sound at a level greater than the mortality and potential mortality threshold previously proposed by the Popper et al. (2014). The fish were exposed to six discharges at an average peak sound pressure level (SPLpeak) of 229 db re 1 µpa. Fish were monitored for 60 hours post exposure and no mortality or significant physiological damage (hair cell or otolith damage) were observed. In another study, individuals of four fish species were exposed to piling noise levels above a peak SPL of 207 db re 1 µpa, but did not suffer any mortal or potentially mortal injuries (Casper et al. 2012).

5 A range of responses have been observed when studying the behaviour of wild fish species in the presence of anthropogenic sounds. Some fishes have shown changes in swimming behaviour and orientation, including startle reactions (Pearson et al. 1992; Wardle et al. 2001; Hassel et al. 2004). Sound can also cause changes in schooling patterns and distribution (Pearson et al. 1992). However, researchers have observed that once acoustic disturbances are removed, fish return to normal behaviour within about an hour (Pearson et al. 1992; McCauley et al. 2000; Wardle et al. 2001). Potential recovery in European seabass and European eel exposed to seismic sound was investigated by Bruintjes et al and Radford et al European seabass experienced 12 weeks of impulsive noise showed no differences in stress, growth or mortality compared to those reared with exposure to ambient-noise playback (Radford et al. 2016). Anthropogenic noise-induced effects quickly dissipated and European eel and European seabass showed rapid recovery of startle responses and startle latency within 2 minutes after noise cessation (Bruintjes et al. 2016). Seabass also showed complete recovery of ventilation rate when exposed to peak SPLs of ~200 db re 1 μpa; whereas eels showed rapid albeit incomplete recovery compared with ambient conditions. The areas of ensonification predicted by the underwater sound modelling for fish were based on the largest area of effect within the survey area. The largest predicted area of ensonification for fish was based on the potential for temporary threshold shift (TTS) effects, i.e. effects that are temporary but recoverable. Although potential injury could occur directly below the source and within a few hundred meters (Table 2), this is a conservative approach because in reality there would be a range of effects within these impact ranges, including recoverably injury (Popper et al. 2014). Furthermore, these mobile species are likely to avoid the approaching airgun well before the noise reaches injurious levels, highlighting the fact that behavioural effects are more likely than physical and physiological effects at lower sound levels (Carroll et al. 2017), and are the most ecologically realistic consideration when assessing the impacts of seismic surveys (Bruce et al. 2018). Based on the expert review carried out by Popper (2018), it is highly unlikely that there would be physical damage to fishes as a result of a seismic survey unless the animals are very close to the source (perhaps within a few meters), with TTS being the most likely (if any) level of effect. Popper (2018) further concludes that if TTS does take place, the duration of exposure to the most intense sounds that could result in TTS will be over just a few hours, and therefore, accumulation of energy over longer periods than a few hours is probably not appropriate. If TTS takes place, Popper (2018) concludes that it is likely to be sufficiently low that it will not be possible to easily differentiate it from normal variations in hearing sensitivity, with recovery within 24 hours. Any fish species that occurs with 500 m to 1.5 km of the seismic source could experience TTS, however effects are recoverable once the seismic vessel has passed overhead. For the undershoot areas, as the seismic vessels will acquire adjacent sail lines between 500 and 1000 m from the preceding sail line less than 24 hours apart, cumulative exposure is possible (if the fish don t move); however, recovery is still expected to occur as soon as the loudest sound passes overhead. CGG has modelled accumulated sound levels for TTS over periods of 24 hours to determine if there may be potential effects from sound received from shots received over a 24 hour period. Modelling received sound levels over 24 hours or longer assumes that very distant single shot SELs will be audible to fish and contribute to hearing fatigue that may eventually result in TTS. An independent review carried out by Popper in 2018 on cumulative TTS levels stated that in reality, fish will not hear sound over these distances, hence including the accumulated sound energy from distant shots over a full 24 hour period SELcum is considered to be highly conservative. Popper (2018) highlighted that it is important to consider how much of the sound is received (heard) by individual fish in a population. Fish will only hear and be exposed to relatively loud sounds close to the sound source for a relatively short period of time. Popper (2018) further explains that the effects of TTS are unlikely to show up in fishes until the intensity of the sound is well above the fish s hearing threshold. For fish species that are free swimming (which include key commercially targeted species) it is likely that there would be no TTS effect whatsoever since fish will likely move away from the sound source as the vessel approaches. There is likely to strong response from fish within tens of meters of the operations and moderate level effects within hundreds of meters, with a low risk of disturbance >1000 m (Popper et al. 2014). Behavioural effects include changes in schooling and feeding behaviour, decreased predatory avoidance (although predators are also likely to be similarly impacted), and disruption to spawning. However, such behavioural changes are expected to be temporary as the seismic vessel traverses each survey line, localised in spatial extent, and

6 most relevant to continental slope habitat which comprises only a small part of the overall survey area. Further, any effects are expected to be short-term and limited to duration that the fish is exposed to the source, which for a pelagic (free swimming) species would be limited to the time taken for the fish to swim away from the source. Fisheries stakeholders have identified Southeast Reef as an important fish habitat and possibly spawning area and CGG has agreed to significantly reduce the power of the source array when running over the top of this area (< 150 in3 compared to 3000 in3) and to avoid any undershooting in this area. For fish planktonic stages, the potential impacts of seismic sound will be similar to those described above for the planktonic stages of invertebrates, and relative to the large area of southern Australian waters where these planktonic stages will occur the impacts on their biomass is expected to be very localised and short-term, with negligible population level effects compared to the natural high rates of planktonic turnover. No medium or long-term effects are therefore predicted for fish species as a result of seismic operations. No significant effects on key biological process of spawning, feeding, breeding or migration, are predicted for commercially important species. Table 2: Modelled Impact Ranges for Fish (including Sharks) Fish Group Fish: No swim bladder (also applied to sharks) Fish: Swim bladder not involved in hearing, Swim bladder involved in hearing Fish: ALL GROUPS (No swim bladder (also applied to sharks), Swim bladder not involved in hearing, Swim bladder involved in hearing) Popper et al. (2014) Exposure Level 213 db re 1µPa (Lpk-pk) Mortality and potential mortal injury / recoverable injury 207 db re 1µPa (Lpk-pk) Mortality and potential mortal injury / recoverable injury 186 db re 1µPa 2.s (SEL24h) TTS Predicted Maximum Impact Distance Shallow water (<200 m) Midwater (200-1,000 m) Deep water (>1,000 m) 80 m 115 m 120 m 145 m 210 m 232 m 500 m 1.1 km 1.5 km Mitigating impacts to fisheries Stakeholder feedback identified concern over the longer-term effect of seismic activity on fish catchability. This is difficult to assess because of the confounding influences of other factors such as fishing pressure, climatic changes and variation in natural population dynamics. A series of studies have been undertaken to determine the effects of seismic surveys on fish catches and distribution, primarily in California (Greene 1985, Pearson et al. 1992), Norway (Dalen and Knutsen 1987; Lokkeborg and Soldal 1993) and the UK (Pickett et al. 1994). While the conclusions from these studies were largely ambiguous due to the inherently high levels of variability in catch statistics, one study noted that pelagic species appear to disperse, resulting in a decrease in reported catches during the surveys (Dalen and Knutsen 1987). More recently, the potential impact on the catchability of commercially important fish species was investigated using a 2D seismic survey in the Gippsland Basin to quantify fish behaviour and commercial fisheries catches across the region before and after airgun operations (Bruce et al. 2018). This study monitored acoustically tagged species (gummy shark, swell shark, tiger flathead) before, during and after the seismic survey and found little evidence of consistent behavioural responses, except for flathead, which increased their swimming speed during the seismic survey period and changed their diel movement patterns after the survey (Bruce et al. 2018). Modelling of logbook data for 15 commercially fished species and two gear types (Danish seine, gillnet) showed that catch rates following the seismic survey were significantly different than predicted in 9 out of the 15 species, with six species (tiger flathead, goatfish, elephantfish, boarfish, broadnose shark and school shark) showing increases in catch following the seismic survey, and three species (gummy shark, red gurnard, and sawshark) showing some reductions (Bruce et al. 2018).

7 The results of this study on fish catch rates in the Gippsland Basin are directly relevant to CGG s proposed survey. Catch rates for commercially important fish and invertebrate species are expected to be unaffected or to recover rapidly following the seismic. Fish and invertebrate species are expected to recover within 24 hours, with recovery beginning as soon as the loudest (most intense) sound passes overhead and they are expected to be catchable when access to the zone is reinstated. The consultation process identified Southeast Reef as an important area for commercial fishing and CGG s strategy to reduce airgun volume to <150 in3 over the reef will be effective in mitigating any impacts on fisheries in this area. Mitigating impacts on spawning fish Commercially important fish species that occur within the area that might be affected by the seismic activity are predominantly broadcast spawners (species that release vast numbers of sperm and eggs into the water column), but some such as octopus deposit them on the seabed. Several species form spawning aggregations on the continental shelf, shelf break and slope; however, no significant spawning aggregation areas are known to occur in the vicinity of the survey area, although information regarding fish spawning is generally not well documented. Recognising the uncertainty in the location of spawning areas, CGG has adopted a control measure to mitigate possible impacts on spawners by assessing spawning periods for key species of Commonwealth and Statemanaged fisheries expected to be active within area that might be affected by the seismic activity. These species are likely to spawn on or around large reef systems such as Southeast Reef. Note that this table does not include information for species that do not spawn within the south-east marine region (tuna, billfish, gemfish west, John and mirror dory, and school and king prawns) or do not spawn during the proposed November-June survey window (sawshark and ribaldo). March and April were identified as the months with the lowest sensitivity for spawning (Table 3). As such, and in recognition of the importance this reef has to fishers (as identified from stakeholder feedback), CGG has committed to acquiring seismic data within the zone that encompasses Southeast Reef in March / April. Table 3 Spawning times for key commercially fished species Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Blue grenadier Tiger flathead Rock lobster Pink ling Blue warehou Eastern school whiting King George whiting Snapper Gummy shark School shark Scallop Pale/Maori Octopus + Dark blue cells indicate spawning period. ** Green cells indicate months of lowest sensitivity. Addressing uncertainty in effects of seismic sound on fish

8 CGG recognises that there are gaps in the scientific understanding of how underwater sound affects marine life, including commercially fished species. Stakeholders identified this as a concern and identified efforts made by CarbonNet for an adjacent survey in funding research to help address the gaps in understanding. CGG acknowledges the initiative by CarbonNet and will assess the findings of that study in terms of the impact assessment for the current survey as soon as they are released publicly. Since the CarbonNet initiative, the Bruce et al (2018) research has been released which provides solid support for CGG s assessment of likely impacts to fish and fisheries in the Gippsland Basin area. Where there is scientific uncertainty in the assessment, whether it be in relation to modelling, effect thresholds, species sensitivities or occurrence and behaviour, a conservative approach has been taken. This ensures a greater level of protection for important fisheries resources. CGG conducts seismic exploration in many parts of the word and recognises the importance of robust scientific evidence to support sound impact assessments in general. In order to improve the understanding and impact assessment for future projects, CGG has contributed to dedicated research programs. Whenever possible, CGG is contributing to advancing science and bridging knowledge gaps on sound and marine life. This northern summer, CGG participated in the first ever test of the response of free-ranging fish to a real seismic survey by supplying one of its seismic source vessels to a world-class scientific research consortium led by the University of Leiden (Netherlands) and supported by the Joint Industry Program Sound & Marine Life. In the experiment, tagged free-ranging fish were exposed to seismic sound and their behaviour was be monitored. The results of this study are not yet available, but will be assessed and made available to inform future impact assessments. Controls adopted in response to stakeholder feedback CGG has responded to specific concerns raised by fishers and other stakeholders by adopting the following controls to reduce environmental impacts to ALARP: The seismic source (airguns) will be reduced to a low power setting when acquiring sail lines within the boundary of Southeast Reef and a buffer area of 500 m around the reef (Figure 1). The airgun array volume will be reduced to <150 in 3 over this area. The 500 m buffer provides protection for any fish at the edge of the reef as the seismic vessel approaches and is based on the distance at which behavioural effects are predicted for fish. There will be no seismic undershooting of the four existing platforms over or in the vicinity of Southeast Reef (Fortescue, Halibut A, Cobia A and Mackerel A). These were included in CGG s initial undershooting plans for the survey. Seismic activity within Zone 5 that encompasses Southeast Reef will be completed during the March - April period, as these months have been identified as having the lowest sensitivity for spawning of commercially important fish and invertebrate species. Adjacent sail (survey) lines will not be acquired (shot) during the main survey over a period of <24 hours to allow recovery of fish species. This does not include the undershoot areas which need to be more intensively surveyed. The Acquisition Area will be divided into 7 zones and fishers and other marine users will be advised ahead of time where the seismic vessel will be operating. This will allow fishers to plan their activities around the presence of the seismic vessel. Regular and effective communications will be maintained throughout the survey to ensure fishers remain aware of the areas of exclusion and where the vessel will be at any time.

9 Ongoing consultation CGG is committed to ongoing consultation with all relevant stakeholders regarding the proposed activity and will continue to address any valid concerns raised throughout the EP preparation, pre-survey and survey period. CGG plans to hold an additional face-to-face meeting in the Lakes Entrance area in response to stakeholder requests. If you would like to comment, or would like additional information, please do not hesitate to contact us using the details below. All communication received will be acknowledged, assessed and appropriately responded to. Please advise if you do not want to receive further updates on this project. CGG has endeavoured to reach all relevant persons, but recognises that further persons may self-identify or come to our attention in coming weeks. Please advise CGG, or pass this update on, if you are aware of any other relevant parties whose interests, functions or activities may be affected by the planned survey. In the event that your feedback is received post EP acceptance, your feedback will be documented and where additional or new concerns or issues are raised, CGG will evaluate your concerns and respond with details on how they will be dealt with. If necessary, additional control measures will be developed to ensure all impacts and risks are managed to as low as reasonably practical and are acceptable. Details of all consultations will be provided to NOPSEMA as required under legislation. Thank you for your ongoing engagement in the Stakeholder Consultation process. Contact CGG Phone: Website: Marine seismic research link:

10 Appendix 1 Underwater Sound Impacts CGG has analysed historic seismic survey data within the Gippsland Basin, and more specifically within the proposed Gippsland MSS Acquisition Area. Two historic surveys were selected for the analysis as their spatial extents covered seabed areas and water depths across the Gippsland MSS Acquisition Area. The seismic streamer data from selected sail lines considered representative of the Gippsland MSS acquisition area were analysed to produce measured sound levels close to the surface (i.e. where the streamers are). These measured levels were compared with the predicted sound levels from the underwater sound modelling to provide some form of validation of the modelled levels. The modelled levels were found to be significantly lower than those predicted by the modelling, which provides an additional level of conservatism and precaution in the impact assessment which is based on the predicted impact ranges based on the modelling. Plankton, Fish Larvae and Eggs Guideline thresholds for mortality to eggs and larvae have been proposed based on the sound exposure guidelines by the ANSI-Accredited Standards Committee S3/SC 1, Animal Bioacoustics Working Group (Popper et al. 2014). These guidelines represent the Working Group s efforts to establish broadly applicable guidelines for ichthyoplankton (fish eggs and larvae). The criteria that Popper et al. (2014) suggest for mortality in eggs and larvae are based on levels measured in the study by Bolle et al. (2012) that indicated no damage was caused by simulated repeated pile driving at 207 db re 1 μpa SPLpeak. More recently, McCauley et al. (2017) reported apparent zooplankton mortality at received levels of 178 db re 1 μpa (SPLpk-Lpk) up to 1.2 km from a seismic airgun. Although this is not a peer reviewed and accepted threshold this level has also been compared with received levels predicted by the underwater sound modelling. Lobsters and Scallops There are no peer-reviewed or recognised sound exposure criteria for invertebrates. Research on the impacts of low frequency sound to marine invertebrates is limited (Caroll et al. 2016). Day et al. (2016) assessed the impact of seismic sound on rock lobsters and their larvae, and scallops. Day et al. (2016) concluded in their paper that the results of their study were broadly applicable to lobster and scallop fisheries throughout the world, and to crustaceans and bivalves in general. The exposure levels from that study have been compared with predicted modelled received levels for benthic invertebrates. Exposure to the maximum measured SPL of 209 to 212 db re 1µPa (Lpk-Lpk) did not result in mortality of any adult lobsters or a reduction in the quantity or quality of larvae; however, a range of sub-lethal effects to adults were observed (Day et al. 2016). Exposure to air gun signals did not result in any mortality in any of the experiments on lobster conducted in the Day et al. (2016) study; therefore, lobsters and other crustacean species are not expected to be killed at these sound levels. Exposure to the maximum measured SPL of 191 to 213 db re 1µPa (Lpk-Lpk) did not result in immediate mass mortality in adult scallops; however, increases in the level of exposure (i.e. repeated exposure to air gun passes) were found to significantly increase mortality. Overall mortality rates in the exposed scallops were at the low end of the range of naturally occurring mortality rates documented in the wild, with control scallops having a total mortality rate of 5% and exposed scallops showing a mortality rate of 9-11% (Day et al. 2016). Cephalopods Squid and Octopus There are no peer-reviewed or recognised sound exposure criteria for cephalopods. There have been no observed cephalopod mortalities directly associated with seismic surveys. Anecdotal evidence from studies exposing cephalopods to near-field low-frequency sound have shown received levels may cause anatomical damage, however research is limited to experiments in artificial tanks, rather than in the wild, and researchers have cautioned extrapolation of the conclusions of these results (Goodall et al., 1990; Popper et al., 2001; Montgomery, 2006; Gray et al., 2016). There is limited information on the hearing sensitivity of octopus to sound stimuli. Kaifu (2008) studied Octopus ocellatus and concluded that the statocyst was responsible for the observed responses kinetic sound energy (particle motion).

11 McCauley et al. (2000) studied captive squid (Sepioteuthis australis) responses during a seismic survey, where squid showed a strong startle response to nearby air-gun start up and evidence that they would significantly alter their behaviour at an estimated 2 to 5 km from an approaching seismic source. McCauley and Fewtrell (2012) studied the behavioural responses of squid to seismic sound levels. In general, squid displayed an increased frequency of alarm responses, particularly at higher sound levels, and increased swimming speed in the direction of the surface as the airgun approached and remaining relatively stationary near the water surface as the airgun signal became most intense. The exposure level (162 db re 1µPa2.s (SEL)) that elicited a strong alarm (avoidance) responses in squid (i.e. squid inking) in the study by McCauley and Fewtrell (2012) has been compared with predicted modelled received levels for the cephalopod species that may occur within the survey area, namely squid and octopus. Fish The thresholds for harm to fish species have been based on the sound exposure guidelines for fish proposed by the ANSI-Accredited Standards Committee S3/SC 1, Animal Bioacoustics Working Group (Popper et al. 2014). The guidelines represent the Working Group s consensus efforts to establish broadly applicable guidelines for fish, with specific criteria relating to mortality and potential mortal injury, recoverable injury and TTS. The Working Group defines the criteria for injury and TTS as follows: mortality and potential mortal injury immediate or delayed death impairment: recoverable injury injuries, including hair cell damage, minor internal or external haematoma, etc (none of these injuries is likely to result in mortality) TTS short or long-term changes in hearing sensitivity that may or may not reduce fitness (defined as any persistent change in hearing of 6 db or greater). Table A: Summary of Fish Injury Exposure Guidelines Type of Fish Fish: no swim bladder (particle motion detection) Fish: swim bladder is not involved in hearing (particle motion detection) Fish: swim bladder involved in hearing (primarily pressure detection) Fish: swim bladder involved in hearing (primarily pressure detection) Source: Popper et al. (2014) Mortality and Potential Mortal Injury (db re1 µpa) Impairment (db re1 µpa) Recoverable Injury TTS >213 db peak (Lpk) >213 db peak (Lpk) >186 db SELcum >207 db peak (Lpk) >207 db peak (Lpk) >186 db SELcum >207 db peak (Lpk) >207 db peak (Lpk) 186 db SELcum N/A 170 db SPLrms 158 db SPLrms

12 The guideline levels for each of the criteria above have been derived from a number of sources. The mortality and recoverable injury guidelines are based on predictions derived from effects of impulsive sounds from piling (Halvorsen et al. 2011), since there are no quantified data for acoustic sources. Halvorsen et al. (2011, 2012) measured the response severity index (RSI) of fish species exposed to pile driving. From this study, the authors identified that an RSI of 2 would be an acceptable level of physiological injury for the fish exposed to pile driving, which corresponded to a peak SPL level of 207 db re 1 µpa. It should be noted that the RSI ranking of 2 relates to mild and non-life threatening injuries. There are few data on the physical effects of seismic airguns (e.g. mortality, barotrauma) on fish, and of these none have shown mortality (Popper et al. 2014; Carroll et al. 2017). Popper et al. (2014) cite studies on seismic sound effects on fish and state that no studies have linked mortality of fish, with or without swim bladders, to seismic sound from airguns or in experimental studies replicating seismic sound fields (Popper et al. 2005; Boeger et al. 2006; Popper et al. 2007; Hastings et al. 2008; Halvorsen et al. 2011, 2012; Casper et al. 2012; McCauley and Kent 2012; Miller and Cripps 2013; and Popper et al. 2015). Empirical evidence comes from a study by Wagner et al. (2015) which exposed gobies to seismic sound at a level greater than the mortality and potential mortality threshold proposed by the Popper et al. (2014). The fish were exposed to six discharges at an average peak SPL of 229 db re 1 µpa. Fish were monitored for 60 hours post exposure and no mortality or significant physiological damage (hair cell loss or otolith damage) were observed. Casper et al. (2012) further investigated the RSI for several fish species; representative of the three fish groups identified by Popper et al. (2014): Group1: fish without swim bladders (sharks, rays, flatfish) Group 2: fish with swim bladders not involved in hearing (salmonids, sturgeons, jewfish, snapper) Group 3: fish with swim bladders involved in hearing and structurally connected to the inner ear, (herring, perch, bass, rockfish). The study did not identify any mortal or potentially mortal injuries in the four fish species exposed to piling sound levels above an SEL of 177 db re 1 µpa2.s (or 207 db re 1 µpa SPL peak). This level was concluded by the authors as being the potential onset of physiologically significant injuries (Casper et al. 2012) rather than mortality, highlighting the highly conservative and precautionary nature of the guideline levels proposed by Popper et al. (2014). It is, however, important to note that the intent of authors in proposing these thresholds was as a first step in setting guidelines that may lead to the establishment of exposure standards for fish (and sea turtles) (Popper et al. 2014). The actual impacts associated with sound levels for the tentative thresholds for mortality/potential mortal injury and recoverable injury proposed by Popper et al. (2014) are therefore deemed to represent the level at which physiological damage may start to occur, as evidenced in the studies by Halvorsen et al. (2011, 2012) and Casper et al. (2012). They do not represent a likely mortal impact zone and empirical field data indicates mortality will not occur at these levels.

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