August 22, 2008
Seismic Devices Not Affecting Gulf Sperm Whales
Endangered sperm whales living in the Gulf of Mexico have not been affected by powerful acoustic devices used by oil companies looking for new sources of hydrocarbons, according to a federally funded study released Thursday.
The $9.3 million study examined the impact of offshore seismic activity for six years. Seismic work involves firing air guns into the water, on the Gulf's sperm whale population, estimated to be around 1,600.The project included researchers from eight universities, but it was managed overall by Texas A&M's Department of Oceanography, with research scientist Ann Jochens and professor Doug Biggs serving as principal investigators.
"The bottom line is that air gun noise from seismic surveys that are thousands of yards distant does not drive away sperm whales living in the Gulf," Biggs explains.
Most of the whales live in the northern Gulf, often in areas heavy with exploration and production operations.
"The two are not mutually exclusive," said Randall Luthi, director of the U.S. Minerals Management Service, which oversees E&P activities in federal waters and which funded the study. "That's the kind of knowledge we need to have."
The study sought to determine the effect of man-made noise like seismic probes for subsea oil and natural gas.
Powerful air guns are fired from specially equipped boats. However, federal guidelines restrict crews from using the acoustic equipment if they spot a whale within one-third of a mile from the vessel.
The technology is used to determine the geologic makeup of the seabed.
Biggs found that some whales, when diving deep into the Gulf to eat, reduced the rate at which they searched for prey when scientists carried out controlled seismic experiments.
Researchers said the whales have been exposed to such noise for several decades, so it's difficult to say how they behaved before the oil companies arrived.
The study involved a sample of 98 tagged sperm whales, the species Herman Melville wrote of in "Moby-Dick." An adult male can measure 50 feet long and weigh up to 50 tons. It can stay underwater for more than hour before surfacing for air.
Biggs says, sperm whales are not often seen because they prefer to stay in the deep waters of the Gulf, usually in depths of 3,000 feet or more and at least 150 miles offshore.
"Sperm whales go to where their food source is, and that means very deep water. So folks that do see them are marine mammal observers who ride the seismic survey vessels and the workers on the big oil and gas rigs, and even that does not happen often," Biggs adds.
The MMS study found genetic and social differences among the Gulf sperm whales and those in the North Atlantic and the North and Mediterranean seas.
"The study has greatly contributed to our knowledge of sperm whales ... (but) it's also raised new questions we need to know more about, such as their feeding and breeding patterns," Biggs said. "There's still a lot we don't know about these huge creatures."
In May, Alaska Native and environmental groups sued to stop exploration by oil companies in Arctic waters frequented by whales, seals and other marine species. The groups were worried about the creatures' well-being, and are protesting federal permits that allow the companies to search for oil and gas using acoustic devices.
Environmentalists say the signals could disrupt tens of thousands of animals as they feed, socialize and travel through the seas of northern Alaska.
They say the practice is especially worrisome to Alaska Natives in the region who depend on the marine mammals for food. The Minerals Management Service and National Marine Fisheries Service, both of which grant permits, are defendants in the suit.