July 1, 2012 in Nation/World

Arctic oil hunt a noisy affair

Scientists worry about effect on marine life
Renee Schoof McClatchy-Tribune
 
File photo

Shell’s seismic vessel MV Gilavar conducts air gun seismic tests in the Chukchi Sea in September 2009. Scientists have been studying the impact of the intense underwater sounds on marine animals.
(Full-size photo)

Surveying with sound

Oil companies use sound to guide their underwater drilling operations. Seismic survey air guns shoot explosions of compressed air that send acoustic energy through the water and into the Earth’s crust. The sound is repeated about every 10 seconds, some 360 per hour, sometimes for hours at a time. Measuring how long it takes to reflect the sound waves back provides information about subsurface rocks. Oil companies use the information to figure out where to drill.

WASHINGTON – As the Arctic Ocean’s ice cover declines in summer and oil companies move in with ships, drilling equipment and seismic surveys, what used to be a mostly very quiet home for whales and other marine animals is getting a lot louder.

Next month will mark a new stage in oil and gas development in the Beaufort and Chukchi seas north of Alaska, when Shell returns to the Alaskan Arctic to drill exploratory wells. If it’s successful, this could be the beginning of a new boom.

Scientists are asking how whales and other marine animals will react to the sound. The overall level of man-made underwater noise in the Arctic is increasing, not only from oil and gas development but also from shipping and soon from commercial fishing and tourism vessels. Whales, dolphins, walruses and seals all rely on sound in the water. Bowhead whales, for example, are adept at using their voices to navigate in complete darkness through ice.

“They can live to 200, and they’re adapted to a world of extreme quiet under the frozen ocean, broken at times by extremely loud tectonic crashes of giant blocks of ice,” said Christopher Clark, the director of the Bioacoustics Research Program at Cornell University.

“An oil spill may be more dramatic in terms of actually exposing animals to toxic substances,” added John Hildebrand, a professor at the Scripps Institution of Oceanography at the University of California at San Diego, “but the stress that may come from the increased noise is something that we should be concerned about.”

The oil company is keenly aware of the potential disturbance below the surface.

“The sound we’re putting in the water is something we’re watching very closely,” because it could directly impact marine mammals and communities that rely on subsistence hunts, said Shell spokesman Curtis Smith in Anchorage. The sound from seismic surveys “is something that’s at the top of our list for mitigating our impact,” he said.

The company has had acoustic recorders in the Beaufort and Chukchi seas for several months at a time since 2006 to understand marine mammals’ behavior, how they respond to the sound Shell puts into the water and also how they respond to climate change and ship traffic sounds.

Oil and gas exploration is loud, often for many hours at a time.

Shell has spent billions of dollars on Alaskan Arctic exploration already, and the company says it’s working to reduce its sound impact on marine mammals.

During its seismic work, Shell was required to hire people to spot marine mammals. When the animals entered a specified zone, Shell would “ramp down” the air-gun work and then slowly increase it again after the mammals moved on.

Shell plans to expand its operations if the next two summers of exploration are successful. Other companies also are getting in. Interior Secretary Ken Salazar on Tuesday announced plans to offer new lease sales in the Chukchi in 2016 and in the Beaufort in 2017. Estimates show 25 billion barrels of oil in the seas – more than the 17 billion barrels of oil that have been produced in the last 30 years on the North Slope.

In May, the National Oceanic and Atmospheric Administration granted Shell permits that allow nonlethal harassment due to sound after it reviewed studies and collected public comments. The agency determined that the drilling this summer wouldn’t kill or injure the animals or damage subsistence hunting. The permit requires Shell to take certain precautions, including slowing ship speeds when marine mammals are nearby and flying helicopters higher to minimize noise.

“There’s always more to learn. But because of statutes and regulations, we’re required to make a decision based on the best science we have,” Candace Nachman, of NOAA’s Office of Protected Resources, said.

Shell also reached an agreement with the Alaska Eskimo Whaling Commission to halt its operations in the Beaufort Sea on Aug. 25 and move its operations out of the area during the Alaska natives’ bowhead whale hunting season.

“There are unanswered science questions,” said Clark, the Bioacoustics Research Program director at Cornell. “It’s not clear what happens if a whale hears 1,000 of the explosions from air guns, or where it will go if an area is saturated with the sound.”


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