A federal government agency's scientists usually don't feel compelled to more fully explain the basis for their decisions. More than a month after the US Bureau of Ocean Energy Management issued a programmatic environmental impact statement covering proposed geophysical activity along the South and Mid-Atlantic Outer Continental Shelf, however, the agency's chief environmental officer did.
"As a scientist who has spent a good part of my career working in nongovernmental environmental organizations and in industry, I understand and appreciate advocacy," said William Y. Brown in the Aug. 22 edition of BOEM's Science Notes. "At the same time, I believe that everyone benefits by getting the facts right."
Oceana, for example, said at its web site on Aug. 25 that seismic air guns "are 100,000 times more intense than a jet engine." The site continued, "Seismic air gun testing currently being proposed in the Atlantic will injure 138,500 whales and dolphins and disturb millions more, according to government estimates."
Brown's response: "To date, there has been no documented scientific evidence of noise from air guns used in geological and geophysical (G&G) seismic activities adversely affecting marine animal populations or coastal communities."
Brown said, "This technology has been used for more than 30 years around the world. It is still used in US waters [in] the Gulf of Mexico with no known detrimental impact to marine animal populations or commercial fishing."
Brown said a large air gun can be loud-but not 100,000 times louder than a jet. "Measured comparably in decibels, an air gun is about as loud as one jet taking off," he wrote. They are powerful, however, which is "why mitigation measures-like required distance between surveys and marine mammals and time and area closures for certain species-are so critical."
Ignoring mitigation steps
Assertions that the government's own scientists expect 100,000 injuries or deaths of marine life if seismic surveys go forward "misrepresent the facts," he added.
"When our scientists began to look at possible impacts of seismic surveys, they first looked at what might happen if no measures were taken to mitigate or avoid possible injury to marine mammals," Brown said. "Next they began to look at what could be done to avoid harm, such as avoiding migration routes and stopping surveys if vessels get close enough to marine mammals to possibly injure their hearing."
The preferred alternative chosen after a thorough public process included the most restrictive mitigation measures that would allow surveys to take place, he explained. "We expect survey operators to comply with our requirements and, if they do, seismic surveys should not cause any deaths or injuries to the hearing of marine mammals or sea turtles," Brown said.
