Although as of 2014 humpback whales are no longer listed as Endangered by the International Union for Conservation of Nature, major threats to their populations include fishing gear entanglement, collisions by ships, impacts on their habitats from pollution and harassment by whale watchers. Future threats include proposed resumption of commercial whale hunting and offshore development of oil and gas mining facilities.
Extensive commercial hunting of humpback whales, which began in the 18th century and carried on into the 20th century, severely depleted global humpback whale populations, especially after the introduction of the explosive harpoon in the late 19th century. In the 20th century alone, whalers killed over 200,000 humpbacks, until the population dropped to approximately 700 whales. The International Whaling Commission was founded in 1946 to protect worldwide whale populations, and in 1966 it banned the hunting of humpback whales. In 1986, humpback whales were declared Endangered by the IUCN. In 1990, their status was changed to Vulnerable. Because of their resiliency in re-establishing themselves with a worldwide population of at least 80,000, the IUCN reclassified humpback whales in the category of Least Concern as of 2008.
As of 2014, commercial hunting of humpback whales is still banned, except by small native groups in areas such as Greenland, St. Vincent and the Grenadines. Humpback whale deaths through entanglement in fishing gear are reported annually by U.S. and Japanese fishermen. Ship strikes, though less frequent, occur. Conservationists are concerned about offshore oil and gas development affecting whale populations in places such as Brazil, Angola, Mozambique, Madagascar and Gabon.