News Feature: US agency finds seismic operations have no significant impact on marine mammals

It’s the outcome that the oil industry had been hoping for. A major environmental impact assessment by the US Department of Interior’s Minerals Management Service (MMS) has concluded that seismic survey operations in the Gulf of Mexico do no discernible harm to marine mammal life. We summarise here some of the key points from the findings, the implications of which may reverberate beyond US offshore activities. In announcing the completion of an environmental assessment (EA) evaluating the potential environmental impacts of geological and geophysical (G&G) activities in the Gulf of Mexico, the Minerals Management Service (MMS) said that the best available information on the effects of seismic surveys on marine resources was analyzed, and in particular marine mammals, including sperm whales. Hundreds of documents were reviewed from around the world. The activities taken into account in the EA include seismic surveys, deeptow side-scan surveys, electromagnetic surveys, geological and geochemical sampling, and remote-sensing surveys which are used extensively to support oil and gas exploration in the Gulf of Mexico. The impact-producing factors considered in the EA included seismic survey noise, vessel and aircraft noise, seafloor disturbance, and space-use conflicts with seismic arrays. Each year there are about 20 MMS-permitted 3D seismic surveys conducted in the Gulf of Mexico. The conclusion of the EA was that G&G activities are not expected to result in significant adverse impacts to any of the potentially affected resources. Potentially adverse but not significant impacts were identified for marine mammals, except the manatee, for which negligible impacts were identified. As a result, MMS has issued a ‘Finding of No Significant Impact.’ The EA will be included as part of an information package used by MMS in the near future to petition the National Oceanic and Atmospheric Administration (NOAA). This petition will request NOAA to issue regulations to allow small ‘takes’ incidental to seismic surveys in the Gulf of Mexico, under the enabling regulations of the Marine Mammal Protection Act. The MMS currently requires operators engaged in activities on the US Outer Conbtinental Shelf (OCS), including G&G activities, to comply with a number of lease stipulations, Notices to Lessees, and other mitigation measures designed to reduce or eliminate impacts to sensitive environmentalresources from impact-producing factors such as vessel or aircraft traffic, anchoring, and trash and debris. These mitigation measures are required under the OCS Lands Act, the Endangered Species Act, and the Marine Mammal Protection Act to ensure environmental protection, consistent environmental policy, and safety. As part of the impact analyses completed in the G&G EA, current protective and mitigation measures were evaluated (Alternative 1). Additional feasible mitigation measures were also considered (Alternatives 2 and 3), as were potential restrictions on concurrent operations within close proximity to one another (Alternative 4), as viable alternatives to further reduce the potential for impacts to marine mammals. The PEA reviewed G&G activities which were the subject of a previous Environmental Impact Statement (EIS) prepared by the US Geological Survey in 1976 and a PEA prepared by the MMS in 1984. A new PEA was needed in light of advances in G&G technology, expansion of activities into deep offshore waters, and improved knowledge of acoustic impacts on marine life. Further, those G&G activities that were previously determined to be categorical exclusions (CATEXs), exempt from detailed analysis (based on previous environmental documents), needed to be revisited and re-evaluated.