Setting the scene
Commercial whaling had slashed Megaptera novaeangliae numbers until the 1966 moratorium and Marine Mammal Protection Act; international cooperation through the International Whaling Commission and habitat safeguards allowed distinct population segments to rebound.
What happened
Most humpback populations were delisted in September 2016 when NOAA Fisheries removed nine of fourteen distinct population segments from the U.S. Endangered Species List, citing sustained growth rates and stable breeding grounds.
Why it still matters
Whale-watching tourism expanded from Maui to Antarctica as singers of complex songs returned in visible pods; conservationists still monitor entanglement in fishing gear and climate-driven shifts in krill distribution that could threaten specific stocks again.
Background
Whale-watching tourism expanded.