DURHAM, N.C. – A new International Union for Conservation of Nature guide, authored by Duke University’s Doug Nowacek, outlines the best practices governments and energy companies should follow to reduce harmful impacts on marine life from underwater seismic surveys’ intense sounds.
In seismic surveys, air guns towed behind ships emit powerful bursts of sound under the water over long periods of time and large distances. On-board sensors then measure the sounds’ return echo to reveal details of the sea floor and its underlying geologic structure.
Surveys can be used for a variety of purposes, but are deployed primarily to pinpoint the location of oil or gas deposits beneath the sea floor, map the continental shelf, and find the best sites for new offshore wind energy projects.
Whales and other cetaceans, pinnipeds, turtles, fish and possibly other marine creatures are all able to hear the loud sounds produced by seismic surveys.
“The noise from seismic surveys can disrupt the essential life functions of marine species, such as breeding, nursing and foraging,” says Carl Gustaf Lundin, director of IUCN’s Global Marine and Polar Programme. “It is therefore critical to turn down the volume and ensure the surveys are conducted in an environmentally responsible way. The new IUCN guide will help in achieving this.”
“Our guide is based on the best available science and methods,” says Duke’s Nowacek, who is a member of the Cetacean Specialist Group of IUCN’s Species Survival Commission. “It draws on observations of operations and associated monitoring and mitigation efforts over several decades of geophysical and other industrial surveys.”
Nowacek is the Repass-Rodgers University Associate Professor of Marine Conservation Technology at Duke’s Nicholas School of the Environment and Pratt School of Engineering.
The new guide assesses the potential risk of various surveys on marine life, and emphasises that surveys must take into account the specific circumstances related to the site. Key factors for consideration include the life history and population status of local species, environmental features and history, and nature of other operations in the area.
Some of the guide’s key recommendations include:
- Having a systematic, risk assessment-based means of conducting effective monitoring and mitigation;
- Reducing the survey area and sound source transmissions to the minimal size necessary;
- Using the smallest source (e.g., smallest number/size of airguns) necessary to accomplish the exploratory goal;
- Avoiding redundant surveys in the same area;
- Pursuing alternative, lower energy sources;
- Ensuring transparency and dialogue with interested stakeholders as well as open access of environmental data in a reasonable time frame.
The guide also includes a comprehensive online compilation of global resources, regulations and references related to each step of the process, which will continue to be updated through an ongoing dialogue with regulatory agencies, industry and civil society organisations.
“Undertaking a structured approach for planning and conducting environmentally responsible seismic surveys and other forms of seabed mapping is now more feasible than ever thanks to the lessons learned from previous operations, sustained research, and improvements in technology,” says Brandon Southall of Southall Environment Associates Inc. and the University of California at Santa Cruz, who authored the new guide with Nowacek. “This guide will help managers and policymakers navigate this process.”
Increased public awareness of the issue of human-generated noise in the ocean has been accompanied by greater involvement by governments and regulators. Parallel to IUCN's efforts, the U.S. National Oceanic and Atmospheric Administration is developing a national strategy for reducing underwater noise, a draft of which was released earlier in the year.
The world’s governments, parties to the UN Convention on Biological Diversity (CBD), are expected to adopt a number of measures recommended by scientists for addressing impacts of underwater noise on marine and coastal biodiversity at the next CBD meeting in Mexico in December 2016.