The Trump administration has approved seismic testing related to oil and gas exploration off the US Atlantic coast. The testing could harm tens of thousands of dolphins, whales and other marine animals. The testing uses blasts from high-powered airguns to map the ocean floor to estimate the whereabouts of oil and gas.

The decision is likely to further antagonize governors in states along the Eastern Seaboard who strongly oppose the administration’s proposal to expand federal oil and gas leases to the Atlantic. Every state executive on the coast below Maine opposed the plan. Federal leases could lead to exploratory drilling for the first time in more than a half-century.

The Washington Post reports that according to a prediction from a 2014 study by the federal Bureau of Ocean Energy Management in 2014, nearly 2.5 million dolphins would be harassed or possibly killed by acoustic sound blasts each year in the middle and southern Atlantic, and nearly a half-million pilot whales would be affected.

Six of the impacted mammals in the study area were endangered species, the report said, including four types of whales. The species most impacted would be humpback whales, 12 of which could be killed each year it said.

Officials currently at the Bureau of Ocean Energy Management are now denying the existence of confirmed evidence that animals are actually harmed by seismic mapping and consider the threat “negligible.”

Rep. Raúl M. Grijalva (Ariz.), the ranking Democrat on the House Natural Resources Committee who will probably take over as chair in the next Congress, blasted the administration’s decision to permit acoustic testing as “an alarming sign of [its] indifference to the fate of coastal communities and marine life, including the endangered North Atlantic right whale.”

He criticized the timing of the announcement shortly after the climate report’s release, saying, “There is nothing this administration won’t do for the fossil fuel industry, including destroying local economies and ruining endangered species habitats.”

In addition to the damage done to whales and dolphins, the increased exploitation of fossil fuels promotes climate change. On the Friday after Thanksgiving, the administration published a report by 13 federal agencies projecting the severe economic costs of climate change as coastal flooding and wildfires worsen and hurricanes are becoming more severe.