The Interior Department said Thursday that sonar testing off the Atlantic Coast would not significantly harm aquatic life, a move that serves as a precursor to potential offshore drilling in the region.

The use of seismic airguns — in which sonar blasts are sent to the ocean floor to detect possible oil and gas deposits in the ocean floor — has been contested by environmental groups who say it stuns and deafens aquatic life, which eventually leads to their death. But its proponents in the oil and gas industry say the technology has improved in recent decades, limiting marine disruption, and that it’s more environmentally friendly than drilling exploratory wells.