Scientific name: Megaptera novaeangliae
Humpbacks are one of the most active whales in terms of behaviour – they frequently breach, slap their tails and fins on the water surface, and males engage in vigorous, even violent competition for mates on their breeding grounds.
Physical description and related species
Unlike their ‘cousins’ the blue, sei and minke whales, humpbacks (Megaptera novaeangliae) are not slender and graceful – they tend to be quite stout and stocky, with exceedingly long pectoral fins (their ‘arms’). They are much slower swimmers than these other species.
Humpback whales grow to about 15 metres, and 40 tonnes in weight. Like all baleen whales, females are slightly larger than males.
Distribution
It is now thought that many female humpbacks – those who are not engaged in breeding activities in a given year – probably remain somewhere in the Southern Ocean to feed and build up their fat reserves for the following season's migration and mating. On migration, humpbacks may not feed for as much as 8 months of the year.
Humpbacks are known to have the longest annual migration of any mammal. They travel from the Antarctic Peninsula south of Cape Horn, across the Equator to Columbia or even Mexico.
Threats
Because they were slow and fat, humpback whales were targeted by whalers well before the faster blues and fins, and were killed by open boat whalers with hand harpoons in the 19th century. However, they survived in numbers until the 1950s and 1960s when illegal whaling reduced their numbers to near-extinction.
Nevertheless, humpbacks seem to be recovering well after whaling ceased, and their numbers are increasing in many areas of the world. The populations, which breed in Australian waters, have doubled in the last 10 years.
Conservation status: least concern
Breeding
Humpback breeding areas are fairly well known (unlike those of most other baleen whales). In Australia they breed inside the Great Barrier Reef on the East Coast and on the Northwest Shelf, along the west Kimberly coast. They migrate close to the shore, and at the right times of the year can be easily seen as they travel past.
Diet and feeding
Humpback whales feed in Antarctic waters on krill of various kinds, but also eat small fish and plankton during their migration south from their breeding areas.
Whale song
Humpbacks communicate among themselves with their famous and beautiful song. A song is usually quite short, less than 10 minutes, but can be repeated many times, sometimes for hours without stopping. It is thought to be mainly a method for mature males to advertise themselves to females as sexual partners.
