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