Humpback whales (Megaptera novaeangliae) are among the world’s largest and most distinctive whales. They grow to approximately 16m in length and weigh up to 50 000 kg making them one of the largest animals on earth. The name humpback describes the way they arch their back just before they dive.
The top half of a humpback whale is usually black while the underside is white though there is much variation with some whales having patches of black and white pigmentation across their body. On the east coast of Australia, a humpback whale that is completely white has been witnessed frequently for the past few years. Most whales have scarring that appears white, particularly on their tail and fins. Individual whales are identified from these distinguishing features.
Humpback whales fall into the group of whales known as baleen whales. This group of whales has two blowholes and rather than having teeth they have baleen. This is a comb-like structure that they use to strain their food from seawater.
One physiological feature that distinguishes humpback whales from other baleen whales is their large pectoral fins that reach up one-third of their body. These are actually limbs complete with long finger bones.
Each year, between May and November, the southern hemisphere humpback whales migrate from their Antarctic summer feeding grounds north to their breeding and birthing grounds in the tropics. Separate populations migrate up the east and west humpback of Africa, South America, Australia and towards the south Pacific islands. The population that migrates up the east coast of Australia is estimated to be up to 17 000 individuals.
Once in the tropics male and female humpback whales mate and pregnant females give birth to calves. The whales then migrate south again to spend the Antarctic summer feeding in preparation for their northern migration the following year.
Humpback whales are believed to use a landmark to assist with navigation. This trait is what ties them so close to the coast. In the past, this behaviour made them vulnerable to commercial whaling operations and a dramatic decrease in the population has been witnessed. Since commercial whaling ceased in the 1970s, the population has recovered significantly but is considerably short of what it was prior to commercial whaling (approximately 28 000).
The fact that humpback whales travel in close proximity to the shore line and that Cape Byron is Australia’s most easterly point makes this region one of Australia’s premier whale-watching destinations. Here you can witness the humpback whale migration, at close hand, without having to travel far.
Size Adults: 14m to 18m (up to 50 tonnes)
Physical maturity: 12 to 15 years
Sexual maturity: 4 to 10 years
Size at Birth: 4m to 5m at birth (2 tonnes)
Gestation: 11 to 11.5 months
Weaning age: Up to 11 months
Calving interval: 2 to 3 years
Migration season: May to December
Swimming speed: 3-4 knots
Blow pattern: Inverted teardrop, up to 5m
Status: Globally populations have reached a point of least concern according to IUCN red list