The Interior Department by early next year is expected to decide whether to allow the first new surveys for oil and gas in the Atlantic Ocean in roughly 30 years, a move that could reveal new energy deposits but potentially harm endangered whales, fish and turtles. While drilling off the Eastern Seaboard is likely several years away, the agency is considering opening waters from Delaware to Florida to seismic testing, which involves the use of air guns that emit powerful seismic blasts.