NEW! Acoustic Ecology Institute has put together a concise, comprehensive Backgrounder on industrial seismic surveys. This 8-page Word document (designed for the media) gives a quick overview of the issue; detailed summaries of the scope, effects, and possible ways of addressing the issue; 2004 research of note; and links to online resources. [DOWNLOAD BACKGROUNDER(doc)]

The search for undersea reserves of oil and gas often begins with seismic exploration. Using sound waves generated by directed bursts of sound from airguns, typically used in multiple arrays, the geology beneath the sea floor can be ascertained. Similar technology is often used for geological research into earthquakes or other earth-science topics. The effects of these sounds on sea creatures is a matter of increasing concern, given the many stresses at play on marine species populations.

Seismic explosions typically peak at 200-230 decibels; scientists believe marine mammals and fish may be injured by sounds in the range of 180dB (generally accepted to be the sound level at about 1km from the airgun). The physical impacts of seismic survey noise on marine mammals are usually considered to be minimal, since the systems ramp up slowly enough to allow animals to move away. However, auditory masking or confusion, temporary hearing loss, and perhaps long-term hearing damage are possible. In addition, there are a wide range of behavioral reponses, primarily avoidance.

Energy-rich areas such as the North Sea and the Gulf of Mexico have been blanketed by surveys for many years, with little evidence of massive die-offs of animals. However, there is increasing concern about the cumulative impacts of these especially loud sound sources on marine life, and there have been occasional instances of coincidental strandings. Each survey (there have often been a hundred a year in the Gulf of Mexico) lasts for anywhere between a few days and a few weeks; the survey ship travels in a grid of parallel tracks, firing the guns every 10-60 seconds.

There are many factors to be aware of in considering the impacts of such sounds, including the different systems used to measure dB in the sea, the differing hearing ranges of various species and source frequencies of noise sources, the prevalance of high-volume shipping noise in the ambient noise of the ocean, and the many unknowns in our knowledge of the perception and use of sound by marine creatures. The AE.org Ocean Acoustics section [GO THERE] is highly recommended reading to get up to speed on these complexities.

AEI Research Report - Seismic Surveys: What we Don't Know Can Hurt - Read executive summary and download full report: [GO THERE]

Greenpeace Overview of Seismic Exploration - [WEBSITE]

Living Oceans Society Literature Collection - Includes a sublist on seismic impacts, including comments submitted by researchers and research reports [WEBSITE]

Lamont-Dougherty Earth Observatory - Website of a leading geology research center run by Columbia University. Includes information on airguns used for academic research. [WEBSITE]
The value of marine seismic research [WEBPAGE]
Indian Ocean Sounds [WEBPAGE]

Oil and Gas Industry Reports and Initiatives Related to Biological Effects of Noise - Industry trade groups and coalitions have sponsored research into the effects of airguns for many years. A new Joint Industry Project (JIP) was initiated in early 2005. In the summer of 2006, this program moved to fruition, launched as the "E & P Sound and Marine Life Programme", and funded with donations from a consortium of oil and gas companies, all part of the OGP. Primary focus of the work is likely to be on marine mammals, with some emphasis also on fish, invertebrates, and other prey species.
E&P Sound and Marine Life Programme [WEBSITE] Summary presented at IWC in June 2006 [DOWNLOAD PAPER(doc)]
OGP (International Association of Oil and Gas Producers) Marine Mammal info, including JIP [WEBSITE]
IAGC (International Association of Geophysical Contractors) Position Paper on Marine Mammals and Sound, 2004 [DOWNLOAD REPORT(pdf)]
IAGC Task Force on Marine Mammals and Sound Goals Paper, 2001 [READ PAPER]
IAGC Marine Mammal info [WEBSITE]
Canadian Society of Exploration Geophysicists [WEBSITE]

Proceedings of the 1998 Seismic and Marine Mammals Workshop - From the Sea Mammal Research Unit at St. Andrews University. [WEBSITE]

Minerals Management Service Programmatic Environmental Assessment - Released in 2004, this EA covers geologic and geophysical activites in the Gulf of Mexico, including seismic surveys. The PEA sets a standard 500m safety radius, and lays the groundwork for MMS to request routine "incidental harassment authorizations" from NOAA for commercial surveys in the Gulf. See article from Petroleum News: [READ ARTICLE] Or, see MMS press release: [READ PRESS RELEASE] MMS PEA: [DOWNLOAD EA(pdf)]

Description of operations of Seismic Airguns - A detailed explanation of the physical operation of airguns, from the website of Robertson Research International, an oil and gas consulting firm. [WEBSITE]

New Zealand Department of Conservation Marine Mammal Action Plan - Covers all impacts on marine mammals; includes specific operations and monitoring objectives for seismic surveys. [DOWNLOAD REPORT(pdf)]

Canadian Department of Fisheries and Oceans Statment of Practice on Mitigation of Seismic Noise - A draft of the new Canadian operational and mitigation standards was released in February 2005. As of late 2005, DFO was still working on the final version. A copy of the peer-reviewed report, entitled “Review of Scientific Information on Impacts of Seismic Sound on Fish, Invertebrates, Marine Turtles and Marine Mammals” (Habitat Status Report 2004/002) is available. [DOWNLOAD REVIEW(pdf)] [WEBPAGE ON STATEMENT OF PRACTICE]

Industrial and academic Seismic Survey projects currently being planned or in operation [GO THERE]

Effects of Bridge Construction Noise on Resident Harbor Seals