More than 1,600 critically imperiled species protected under the US Endangered Species Act (ESA) face losing further federal protections following a new reinterpretation of the 1973 law by the Donald Trump administration.

A September 14 memo distributed to Fish and Wildlife Service (FWS) field offices by FWS director Brian Nesvik calls for a reinterpretation of what it means to “take” an endangered species. Under the ESA, “take” is defined as “to harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect, or to attempt to engage in any such conduct”.

The memo, obtained and shared by the Center for Biological Diversity, reinterprets the law to mean that harming or killing an endangered animal would no longer be considered illegal unless the action was specifically intended to cause harm or death.

“A vessel that inadvertently strikes a whale has not taken it, because the vessel’s course was not set against the whale,” the memo said, adding: “Felling a tree is not a take of the bats roosting in it unless the tree is felled for the purpose of killing or capturing them.”

The reinterpretation effectively excludes economic activities such as logging, mining and industrial development from the ESA’s prohibition on “take” when those activities foreseeably kill or injure wildlife without intentionally targeting them.

The memo follows the Trump administration’s repeal in July of the ESA’s definition of prohibited “harm,” which was defined as “an act which actually kills or injures wildlife,” including acts that “may include significant habitat modification or degradation”.

Interior secretary Doug Burgum justified the repeal in July by saying: “For years, federal agencies abused the ESA to obstruct lawful land use and burden American families and businesses.”

Earlier this month, 20 states and Washington DC sued the Trump administration over its decision to redefine “harm,” including removing “modification or degradation” of habitat from conduct that can constitute a prohibited take.

In a statement on Thursday to the Guardian about the administration’s reinterpretation of “take,” the interior department, which oversees the FWS, said: “As outlined in the final rule, the department determined that the previous regulatory definition of ‘harm’ expanded the Endangered Species Act’s prohibition on ‘take’ beyond the text Congress enacted. The final rule restores that interpretation while maintaining the ESA’s core protections for listed species.”

The memo has drawn swift backlash from environmental advocacy organizations. The Center for Biological Diversity pointed to the supreme court’s 1995 6-3 decision in Babbitt v Sweet Home Chapter of Communities for a Great Oregon, in which the majority rejected the argument that “take” is limited to actions deliberately directed against endangered species.

“If you chop down a tree full of endangered birds or race a huge ship through a pod of endangered whales, you should be held accountable for your destructive acts,” Brett Hartl, the Center for Biological Diversity’s government affairs director, said.

“But this administration wants to give wildlife killers a get out of jail free card. Imposing new limitations on the entire definition of take is a flagrant and illegal attempt to rewrite the Endangered Species Act via unilateral fiat. This would drive imperiled species over the cliff to extinction,” he added.

Similarly, the environmental law nonprofit Earthjustice told the Guardian: “The government’s new legal position is a prescription for extinction. It says that as long as you claim you didn’t mean to kill an endangered species, the law can’t and won’t stop you. That’s ridiculous.

“The supreme court decided this issue in the Sweet Home case and its ruling still represents the best reading of the Endangered Species Act. We’ll see the Trump administration in court about this.”

The Trump administration’s reinterpretation of the ESA is the latest in a series of environmental rollbacks. Since returning to office last January, Trump has moved to weaken federal protections for old-growth forests, potentially jeopardizing habitat for 400 endangered species across the US; scrapped drilling restrictions near a world heritage site in New Mexico; and directed his administration to consider the delisting of gray wolves from the ESA.

During the signing ceremony for the latter, Trump asked: “You can shoot them as of today?” Agriculture secretary Brooke Rollins replied that Burgum “has to do a little magic, but yes”.