Species informationSpecies information

Species information

The humpback whale is a moderately large baleen whale (order Cetacea, family Balaenopteridae). The species is found virtually worldwide, but with apparent geographical segregation. Each year Australian humpback whales migrate from Southern Ocean summer feeding grounds to sub-tropical winter calving grounds. The northern and southern hemisphere populations appear to be distinct given temporal migration separation.

In the 19th and 20th centuries, humpback whales were hunted extensively throughout the world’s oceans and as a result it is estimated that 95% of the population was eliminated. In Australia, it is estimated that humpback whales were reduced to 3.5 - 5% of pre-whaling abundance. The International Whaling Commission (IWC) imposed a ban on humpback whaling in the southern hemisphere in 1963 and an international moratorium on commercial whaling came into effect in 1985-86.

In Australia, humpback whales are distributed throughout the Australian Antarctic, Commonwealth offshore, State and Territory waters. Australia has two migratory populations of humpback whales, a west coast and an east coast population (known as Group D and Group E respectively in international fora). Population levels prior to exploitation are difficult to estimate but it has been suggested that the west coast population was between 16,000-30,000 and the east coast population was approximately 27,000. In 1999, the west coast population was estimated to be between 8,000 and 14,000 individuals with a rate of increase of approximately 10.14% from 1982 to 1994. In 1999, the east coast population was estimated to be 3,160-4,040 individuals with a rate of increase of approximately 10.9% from 1978 to 1999. It is likely that these rates of increase will fall as the populations near maximum abundance.

Humpback whales utilising Australian waters currently have tropical calving grounds along the mid and northern parts of the east and west coasts of Australia, and feeding grounds in the Southern Ocean. The majority of humpbacks in Australian waters migrate north to tropical calving grounds from June to August, and south to the Southern Ocean feeding areas from September to November. The exact timing of the migration period can change from year to year and may be influenced by water-temperature, the extent of sea-ice, predation risk, prey abundance and location of feeding ground.

Feeding is likely to be related to krill density and primarily occurs in Southern Ocean waters south of 55°S. However, several opportunistic feeding areas have also been found off the coast of Australia. The available information suggests that a portion of the east coast population disperses into the South Pacific including New Caledonia, Tonga and probably other western South Pacific Islands. Although there are known links between these areas, the levels of exchange are poorly understood and the rates of recovery are likely to be lower for those found near the island groups than close to the east Australian coast.