Humpback Whales

Barnacles on humpback

Scientific name

Megaptera novaeangliae

The genus name Megaptera comes from the Greek for 'Big wing' and the species name, novaeangliae, from the Latin for 'New England', which is derived from the area from which the original ('type') specimen described by Borowski in 1781 originated (Clapham 2002).

Identifying features

Long pectoral flippers, up to one-third of the length of the body (hence the name 'big wing'); 'knobby' protuberances, called tubercles, on the leading edge of the pectoral flippers and on the rostrum (head); scalloping along the trailing edge of the tail flukes; distinctive arching of the back before diving (hence the common name 'humpback'). Humpbacks do not have teeth, but instead have between 270-400 baleen plates on either side of the mouth. Baleen is made of keratin, much like human hair and fingernails, and is used to filter small prey from the water.

Size at birth

4 - 4.5m and weighing ~1-2 tonnes

Adult size

~12 - 15m and weighing 25 - 40 t. Females are generally larger than males by about 1-1.5m.

Gestation

Gestation lasts 11.5 months and the calf is weaned by the end of the first year after birth. Females give birth on average every second or third year, but some females have been shown to give birth two years in a row.

Maximum age

At least 48 yrs, but likely to be higher and probably closer to 100 yrs.

Distribution and range

Dorsal

Humpback whales are found in all oceans of the world and, like most baleen whales, undertake a seasonal migration from summer feeding grounds in polar waters to winter breeding grounds in warmer tropical and sub-tropical waters.

The humpback whales found off the east coast of Australia are part of the Southern Hemisphere Group E population that generally feeds in Antarctica (Area V - 170° W to 130° E) from December to April and migrates to the Great Barrier Reef to mate and give birth from June to October.

Population size

Before whaling, this population was likely to number more than 26,000 individuals (over 35,000 Area V humpbacks were killed between 1949 and 1962). Illegal whaling by the former Soviet Union included more than 25,000 humpbacks killed in waters south of Australia and New Zealand in the two summers of 1959/60 to 1960/61. Recent estimates suggest that by the late 1960s as few as 104 humpbacks were left in this population (Bannister & Hedley 2001).

The abundance of the population migrating along the east coast of Australia was estimated to be 7024 in 2005 (Paton et al., in press). This population is generally increasing at approximately 10-11% per annum, and is estimated to be around 30,000 individuals in 2017.

Prey

Southern Hemisphere humpback whales eat krill (small shrimp-like crustaceans) almost exclusively, but some humpbacks also feed on small schooling fish.

Mortality and threats

Humpback whales, especially calves, are preyed upon by killer whales (Orcinus orca), and there are also some records of large sharks attacking humpback whales. The major threats to humpback whales are from whaling, entanglement, ship strike and pollution.

For the first time since the species was protected in Southern Hemisphere waters in 1963, humpback whales face the potential threat of being slaughtered by Japanese special permit 'scientific whaling' expeditions in Antarctica. However plans by the Japanese whalers to include this species in their 'scientific whaling' program have been postponed in recent years.