Whales and dolphins are protected by federal law. A new federal policy may still kill thousands of them.

On Friday, the National Marine Fisheries Service officially allowed five companies to conduct seismic tests in the Atlantic Ocean in search of oil and gas. These "deafening" searches disrupt fisheries along the coast and could "could kill tens of thousands of dolphins, whales and other marine animals," The Washington Post reports.

Seismic tests use "loud air gun blasts" — every few seconds, and sometimes for months on end — to echolocate broad areas where there could be oil and natural gas wells in the ocean floor, Bloomberg writes. Companies then use exploratory drilling to narrow down where those wells are — a type of drilling that caused the Deepwater Horizon oil spill, per the Post. The tests are also dangerous in themselves, with booms reaching hundreds of miles from where they originated and possibly killing "whales, dolphins, sea turtles, and fish" in their wake, environmental advocacy group Greenpeace says.

These dangers led former President Barack Obama's administration to deny seismic testing permits, the Post notes. But the move is perfectly in line with President Trump's policies, seeing as he's pushed for "energy dominance in America." Supporters also say seismic testing limits the amount of unnecessary drilling companies take on before finding a well, per Bloomberg.

Dozens of state and local officials along the Atlantic coast will likely oppose the testing, the Post says, seeing as offshore drilling could disrupt tourism along with marine wildlife. Read more about seismic testing at The Washington Post. Kathryn Krawczyk