The regulators perspective on marine seismic surveys: Identifying and managing environmental impacts

Article published in the Regulator | Issue 2: 2018

In its position as Australia’s offshore oil and gas regulator, NOPSEMA has noticed increasing debate and disagreement in the public domain about the potential environmental impacts of marine seismic surveys. A lot of concern has been fuelled by media reports and social media posts linking unrelated pieces of information or events, much of which is unsubstantiated. This article seeks to provide NOPSEMA’s perspective as the independent, evidence-based, decision-maker.

So what are marine seismic surveys? Marine seismic surveys are one of the first steps in the offshore petroleum exploration process and are used to assist oil and gas companies in identifying hydrocarbon deposits below the sea floor. Typically, they involve a vessel towing an array of different sized chambers, filled with compressed air across a survey area. The release of compressed air produces sound waves that bounce off underground rock formations and the returning sound waves are then captured by the hydrophones being towed behind the vessel. By analysing the collected soundwaves, geophysicists and geologists are able to build a picture of underground rock formations and more accurately define where hydrocarbon deposits might be.

Marine seismic surveys, as with any other human activity, have an impact on the environment. Some scientific research into the effect of sound generated from seismic surveys demonstrate a range of potential impacts in the marine environment from temporary behavioural disruptions in whales to increased rates of mortality in some marine invertebrates. The type and degree of environmental impacts from a seismic survey is influenced by a number of factors specific to that survey. These factors include the ecological, social, economic and cultural features of the environment the survey is proposed to be conducted in; the type of equipment that will be used; and the way the survey will be managed. This is one of the reasons why every seismic survey proposed in Commonwealth waters requires its own environment plan.

Vital to understanding what the environmental impacts of a particular marine seismic survey may be, requires a comprehensive environmental impact assessment. A part of this assessment includes applying relevant scientific research in the context of the factors specific to proposed survey and the environment it is proposed to be conducted in. Once the environmental impacts of a particular seismic survey are understood then actions can be proposed to eliminate or reduce those impacts to as low as reasonably practicable and acceptable levels. Such actions may include implementing internationally recognised control measures such as restricting the timing and duration of the survey, deploying marine fauna observers to ensure sound emissions are ceased/reduced in power if marine mammals are detected, or not allowing the survey to be undertaken in particularly environmentally sensitive areas.

To draw a comparison, it is widely acknowledged that commercial fishing has an impact on the environment through the removal of fish, potential damage to marine habitats, and potential mortality of species that are not being targeted for sale. But, it is also recognised that if these impacts are appropriately identified and managed, we can continue to enjoy the benefits of sustainable fishing into the future. It is for this reason commercial fishing is closely managed by fishers and regulators to ensure that fish stocks are sustainable and impacts on the marine ecosystem are managed to acceptable levels.

To ensure the impacts of marine seismic surveys are managed to acceptable levels and there is no long-lasting or widespread damage to the environment, NOPSEMA assigns a team of environment specialists to assess each proposed survey through the submission of an environment plan. That assessment takes into consideration all the factors specific to the survey being proposed, contemporary and relevant scientific research and any information provided by stakeholders. It also involves iterative discussions and meetings with the titleholder proposing the survey to ensure appropriate and commensurate actions are taken to protect the environment; if they are not then NOPSEMA will not accept the plan and the survey will not be allowed to occur.

It is important for discussion and debate on the environmental impact of marine seismic surveys and whether or not they are acceptable be based on an objective assessment of the best available information and relevant scientific research. With this in mind, NOPSEMA strongly encourages stakeholders to openly share their perspectives, information and research so that we can develop a common understanding of potential impacts and how they may be managed to as low as reasonably practicable and acceptable levels.