Citing rebounding populations, the National Oceanic and Atmospheric Administration on Monday proposed removing Endangered Species Act protections for most of the world's humpback whales.
Donna Wieting, director of NOAA Fisheries' Office of Protected Resources, said the proposal shows that the Endangered Species Act worked to preserve humpbacks, known for their underwater songs and the way they leap from the water.
"I think that's really important success for us as a nation," she said in a telephone news conference.
The proposal by NOAA would reclassify the whales -- currently listed as endangered throughout their range, including off the Alaska coast -- into 14 distinct population segments around the world.
Under the proposal, 10 of those 14 populations would no longer warrant protection under the under the act, the agency said.
Among the populations NOAA proposes to delist are two found in Alaska waters -- the Central North Pacific population, which breeds off the Hawaiian Islands, and a Mexico-breeding population that migrates in summer to waters off Alaska and the Pacific Northwest.
A third population, the Western North Pacific, which breeds around Okinawa and the Philippines and migrates in summer to the waters around the Aleutian Islands and adjacent parts of Russia, would be listed as threatened.
If approved, the proposal would accomplish the goal sought by the state of Alaska, which last year petitioned for a delisting of the Hawaii-breeding central North Pacific population. The state argued that population growth justified delisting of that population.
But NOAA's complex humpback-reclassification proposal rejects the argument made in a 2013 petition filed by the Hawaii Fishermen's Alliance for Conservation and Tradition that had sought to delist the entire North Pacific population.
Monday's announcement kicks off a 90-day public comment period. A final rule is expected in a year, NOAA officials said.
Even before the state of Alaska and the Hawaii organization filed their delisting petitions last year, NOAA was evaluating humpback whale populations and potential changes to ESA status, Wieting said. That biological review started in 2010.
There is one major reason, she said, for the recent health of most humpback populations -- the cessation of commercial whale hunts.
"Their populations have rebounded since the days of commercial whaling and when they were first listed under the Endangered Species Act," Wieting said. "That and other threats that were facing those species have been addressed."
Some threats, such as risks from ship strikes, are ongoing, but they can be addressed through the Marine Mammal Protection Act, Wieting said.
NOAA biologists distinguished the population segments by using genetic information and analyzing migratory routes and breeding grounds, said Marta Nammack, NOAA Fisheries' national Endangered Species Act listing coordinator
The Alaska populations have "entirely different migratory patterns" and different genetics, she said.
The Hawaii-breeding population, also known as the Central North Pacific, has about 10,000 whales and is growing at a rate of 5.5 percent to 6 percent a year, Nammack said. The Mexico population numbers about 6,000 to 7,000 whales, and the Western North Pacific population consists of about 1,100 whales, she said.
For mariners, fishermen and others conducting activities in humpback-whale territory, delisting is not expected to cause noticeable changes to the conservation rules because the Marine Mammal Protection Act will still apply, the NOAA officials said.
"We really don't anticipate that there will be major or even moderate real differences. The MMPA is a very comprehensive statute that provides many, many protections to marine mammals," said Angela Somma, chief of NOAA Fisheries' endangered species division
The main difference would be for federal agencies, which will no longer have to engage in Endangered Species Act consultations if delisting occurs, Somma said at the news conference.
Some environmentalists were wary of the delisting plan.
"It's heartening to see that some humpback whales are recovering, but it's premature to remove protections when so many threats, like climate change and ocean noise, are increasing," Miyoko Sakashita, oceans director at the Center for Biological Diversity, said in a statement. Humpbacks are "still drowning in fishing gear and getting hit by ships," though they have benefited from the end of commercial whaling, she said.
"The fact that we can spot humpback whales breaching and playing in the ocean after they were nearly extinct shows the tremendous power of the Endangered Species Act. Those safeguards should stay in place for these extraordinary animals," Sakashita said.
The Hawaii-based Pacific Whale Foundation cited climate change and acidification as new threats that should justify continued protections.
NOAA is conducting research into climate change, Wieting said. However, "At this time, with respect to this species, we do not see that as a factor at this point," she said.
Among all the world's distinct humpback population segments, the West Australian is the largest, with an estimated 21,800 animals and an annual growth rate of 10 percent, according to NOAA. The smallest are the Cape Verde/Northwest African and Arabian Sea populations, which have an unknown number of whales but are "very small," Nammack said.
Because of a recent federal court decision striking down a delisting of wolves in the Lower 48 states, there is some legal question about agency powers to list or de-list based on identification of distinct population segments.
The humpback proposal takes that court decision into account, Wieting said. "We believe that we have the ability to identify those distinct population segments and then simultaneously propose how they should be listed under the Endangered Species Act," she said.