The Obama administration announced Friday that it would allow exploration for oil and gas off some portions of the Atlantic Coast using sonic testing devices that environmentalists say harm marine life.

The Interior Department's Bureau of Ocean Energy Management gave the OK for seismic airgun testing, which are boat-towed cannons that shoot sonar blasts off the ocean floor to scan for oil-and-gas deposits, in the mid- and south-Atlantic areas that stretch from the Delaware Bay to just south of Cape Canaveral, Fla. The approval is a prelude to potential offshore drilling there, though that is blocked through 2017 under President Obama's five-year offshore drilling plan.

"The bureau has identified a path forward that addresses the need to update the nearly four-decade-old data in the region while protecting marine life and cultural sites,” said Acting BOEM Director Walter D. Cruickshank, who noted the agency has several permits on hand to conduct the seismic tests. “The bureau's decision reflects a carefully analyzed and balanced approach that will allow us to increase our understanding of potential offshore resources while protecting the human, marine and coastal environments.”

It's a big victory for the oil-and-gas industry, which is nearing its first chance to drill in the Atlantic Ocean in more than 30 years. It comes as BOEM recently raised its estimates for technically recoverable oil in the region to 4.72 billion barrels of oil and 37.51 trillion cubic feet of natural gas -- 43 percent and 20 percent higher, respectively, than agency estimates in 2011.

Obama intended to open the Atlantic Coast to drilling in 2010, but reversed course following the BP Deepwater Horizon disaster in the Gulf of Mexico that April. The incident resulted in 11 deaths and about 4 million barrels of oil spewing into the Gulf, the largest spill in U.S. history.

Some restrictions do exist under the plan, Cruickshank said. Companies conducting the seismic tests will be subject to scrutiny by protected species observers, multiple seismic surveys can't occur in the same space simultaneously, and some critical migratory areas for the endangered north Atlantic right whale will be off limits.

Jeff Vorberger, vice president of policy and government affairs with the offshore drilling group National Ocean Industries Association, said those conditions could hamstring U.S. companies compared with their offshore competitors.

“While NOIA welcomes this decision to finally move forward on new Atlantic seismic data collection, we remain concerned this process will be hindered by unnecessary hurdles lacking scientific justification," Vorberger said.

The move comes over the objection of environmental groups that said seismic airguns deafen and scatter marine life, eventually leading to death from fleeing habitats or injury. The groups, with some East Coast Democrats, argue allowing the activity would threaten tourism and commercial fishing operations.

"According to the government’s own estimates, these dynamite-like blasts could injure and possibly kill up to 138,200 marine mammals, while disrupting the necessary activities of millions more," said Claire Douglass, campaign director with conservation group Oceana, who noted 730,000 tourism, fishing and other jobs would be at risk.

Michael Jasny, director of the Natural Resources Defense Council's marine mammal protection project, said the decision would put marine life at risk and accelerate development of fossil fuels that exacerbate climate change.

“Not only is seismic exploration a gateway drug to offshore drilling, it is a major assault on our ocean itself, with far-reaching impacts on marine mammals and fish," he said.