U.S. fisheries managers on Monday proposed lifting protections for most humpback whales around the globe, including in American waters, based on evidence the mammals have made a strong comeback since commercial whaling drove them near extinction.

The humpback whale is currently listed as endangered throughout its range. But under a plan that opened on Monday for public comment, the National Oceanic and Atmospheric Administration is proposing to classify most of the world's humpback populations into 14 groups with varying forms of protections under federal law.

The stripping of safeguards under the Endangered Species Act means U.S. ships and commercial fishermen in international waters would no longer be bound by law to check levels of underwater noise that could constitute harassment of the whales, while vessel strikes that kill or injure the humpbacks might not be closely tracked.

The proposed reclassification would see most humpback whales that enter U.S. waters in states such as Hawaii and California removed from the federal endangered and threatened species list along with eight other populations in countries including Mexico and Australia, said Donna Wieting, director of NOAA Fisheries' Office of Protected Resources.

The whales would remain endangered, providing the strictest of protections, in the Arabian Sea and off the Cape Verde Islands in northwest Africa. They would be upgraded to threatened in Central American waters and the western North Pacific off Japan, according to the proposal.

U.S.-funded projects in other countries must abide by endangered species protections, as must U.S. commercial fishermen operating in international waters.

The sweeping changes proposed for humpbacks come as government scientists estimate their current numbers in the tens of thousands worldwide, compared with fewer than several thousand when they were listed as endangered in 1970.

The whales, once prized by hunters for their fat or blubber, can weigh up to 40 tons and span as many as 18 metres in length. Humpbacks are best known for periodically jumping out of the water, or breaching, behaviour that has attracted throngs of people who take to the seas to engage in whale-watching.

Commercial whaling was outlawed in 1966 by the International Whaling Commission. Humpback deaths in recent decades have resulted from ship strikes, entanglement in fishing gear, destruction of their marine habitat and incidental harassment by whale watchers, according to NOAA.

Earthjustice attorney David Henkin said the environmental law firm welcomed news that humpback numbers were climbing, but said those gains came from the protections federal fisheries managers were now proposing to lift.

He said conservationists were reviewing the proposal to learn if it was anchored by scientific data and not politically driven.