Passive acoustic monitoring as an environmental protection tool in marine seismic operations

Chris Walker and David Hedgeland, PGS Research Centre, London discuss measures being taken to mitigate the environmental impact of acoustic noise in marine seismic surveys and the uncertainty which still surrounds the issue of ‘acoustic pollution’. The oil industry has responded positively to concerns about the impact of exploration and production (E&P) activity on the environment by introducing a range of environmental protection measures that cover the full spectrum of oil sector operations, from exploration in frontier areas, through production in mature fields to abandonment of exhausted reservoirs. In recent years, however, one specific area of concern has arisen regarding the level of noise in the oceans world-wide – so-called ‘acoustic pollution.’ Whilst there are many natural sources of underwater noise (Fig. 1), the potential impact of man-made noise on the health and behaviour of marine mammals has been highlighted, particularly as activity has moved further and further offshore into areas which have previously been their exclusive preserve. With the adoption of the Agreement on the Conservation of Small Cetaceans of the Baltic and North Seas (ASCOBANS) treaty in Europe and the Marine Mammal Protection Act in the USA, it has become a regulatory requirement to minimise acoustic disturbance to these animals. Such agreements are enforced within each country by national guidelines or regulations. In the UK, the Joint Nature Conservation Committee (JNCC) advises the UK government on formulating guidelines in response to the European Union Habitats Directive and ASCOBANS. Similar organizations in the USA, Brazil and Australia are the Minerals Management Service (MMS), Instituto Brasileiro do Meio Ambiente e dos Recursos Naturais Renováveis (IBAMA) and Environment Australia respectively. In the USA, for example, the existing environment legislation is currently under review in order to take account of increased E&P activity in the deep water areas of the Gulf of Mexico.