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Project (East Span Project), a major public works effort to make the SFOBB “earthquake proof” (Caltrans, 2001). In addition to marine mammals, the major issues were endan- gered salmon species and impact on commercial fisheries. During the PIDP three 2.4-m diameter steel pipe piles were driven into the seabed with two different sizes of hydraulic impact hammers in effort to identify potential problems and test effectiveness of sound attenuation equipment. The immediate mortality zone for fishes was estimated to be within 10-12 meters of a pile without attenuation devices, but the potential for significant acoustic impacts extended far beyond this range.
A global environmental issue
The beaked whale stranding events, an increasing number of seismic surveys to meet the worldwide demand for oil and natural gas, and continued offshore pile driving activities at the start of the 21st century pushed the issue of ocean noise and marine animals to new heights. In 2003 the U.S. Congress passed legislation that directed the Marine Mammal Commission (MMC) to “fund an international conference or series of conferences to share findings, survey acoustic threats to marine mammals, and develop means of reducing those threats while maintaining the oceans as a global highway of international commerce.” In response, the MMC convened a Federal Advisory Committee on Acoustic Impacts on Marine Mammals (MM FACA), consisting of 28 representatives from various stakeholders, including non-governmental environ- mental organizations, the U.S. Navy, oil and gas companies, geophysical contractors, shipping industry, government agen- cies, and the scientific research community (MMC, 2007). The MM FACA met six times in plenary meetings from February 2004 through September 2005 (more information can be found at http://www.mmc.gov/sound/). In addition, the MMC convened two international workshops—the Beaked Whale Technical Workshop in Baltimore, April 2004, and the Policy on Sound and Marine Mammals: An International Workshop in London, September 2004. But at their last plenary meeting, the MM FACA still could not reach consensus on recommen- dations to address the marine mammals and noise issue, so the report to Congress included a findings report and recommen- dations from the MMC, plus seven individual statements from the various stakeholder groups (MMC, 2007).
In October 2004, the European Parliament called for a moratorium on deployment of all active naval sonar until a global assessment of its impact on marine life could be com-
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pleted (European Parliament, 2004). This was followed by
the first Inter-Governmental Conference on Sonar and Marine Mammals, convened in Lerici, Italy, in May 2005 by ONR-Global and the NATO Undersea Research Center. In 2005 the International Council for the Exploration of the Sea (ICES) headquartered in Copenhagen, also issued a report on the impacts of sonar on cetaceans and fish (ICES, 2005).
Although global attention was focused primarily on sonar and beaked whales during this period, Caltrans continued to work on the pile driving and fish issue. The Bay Planning Coalition and Caltrans organized and sponsored a Pile Driving Educational Workshop in October 2003. At this time NOAA
Fisheries was requiring acoustic monitoring of all pile driving operations along the California coast, no matter how large or small. The additional costs for monitoring were threatening to put small piling contractors out of business. In 2004 Caltrans formed the Fisheries Hydroacoustics Working Group (FHWG), which included environmental, scientific and engi- neering experts, and representatives from NOAA Fisheries, California Department of Fish and Game, and the U.S. Department of Transportation (DOT), to work towards con- sensus on noise exposure criteria for fish. They also teamed with the DOT, and state departments of transportation in Washington and Oregon to form a pooled fund to support research needed to understand the effects of pile driving sound on fish. The first research project was funded in 2006.
The oil and gas industry also focused its efforts to address the effects of sound from offshore exploration and production (E&P) activities on marine life. In August 2005 the International Association of Oil and Gas Producers held an International Workshop on Sound in the Marine Environment in Halifax with over 50 participants from the global research community to help draft a research agenda for a proposed funded research program to address impor- tant issues and information gaps. Then, in May 2006, seven international companies formed an executive committee to run the second phase of a joint industry program (JIP) to address E&P Sound and Marine Life. Since that time corpo- rate membership in the JIP has more than doubled. This group regularly posts requests for proposals on its website, www.soundandmarinelife.org. During its first 12 months, the JIP issued 27 research contracts for nearly $8 million dollars (JIP, 2007). This level of funding will help fill critical data gaps needed to understand and improve mitigation of acoustic impacts in the ocean environment.
Progress in understanding the effects of sound on marine animals
Research on effects of sound in the marine environment has focused primarily on understanding criteria and thresh- olds for physiological and behavioral effects, location and abundance of marine animals, and sound source characteris- tics and propagation paths. These studies include laboratory experiments on captive animals where received sound levels are carefully measured and correlated with tissue damage, changes in hearing sensitivity, and/or changes in behavior; controlled exposure experiments in the wild to determine behavioral responses where the sound incident on an animal or group of animals is measured and the transmission path between the sound source and animal receivers is defined; and numerical modeling efforts to integrate large data sets with physical understanding to form predictive models to aid in risk analyses and environmental planning. In addition, research on monitoring and mitigation of potential acoustic impacts has facilitated advances in both fixed and deployable passive acoustic monitoring systems for detection, classifica- tion and localization of marine mammals. These systems can also be used in the field to study the behavior of vocalizing and echolocating marine mammals.
Although many questions remain to be answered, much
24 Acoustics Today, April 2008