An estimated 35,000 whales, mainly humpbacks and southern right whales, migrate along Australia's east coast between May and November each year. From mid-May to August the whales migrate north to mate and give birth in the sub-tropical waters of the South Pacific region. The southern migration takes place from August to mid-November when mothers and newborn calves make their way back down to the feeding grounds in Antarctica.
The exact timing of the migration period can vary from year to year depending on water temperature, sea ice, predation risk, prey abundance and the location of their feeding grounds. Groups of young males typically lead the migration while pregnant cows and cow-calf pairs bring up the rear. Adult breeding animals form the bulk of the migration in the middle stages.
At a maximum length of 16 metres, the humpback is not the largest whale found in Australian waters but it is arguably the most iconic. Recognised by Australians today as more valuable alive, both environmentally and economically, this species was once valued only when it was dead — mainly for its oil and baleen, or ‘whalebone’. The southern right whale is 15-18 metres in length and can weigh between 47 and 80 tonnes.
Southern Right Whale
Beginning in Australia shortly after European colonisation, whaling and the export of whale products became Australia’s first primary industry. Australian whalers of the early 19th century hunted from small boats, towing their catch back for processing at shore stations. The development of harpoon guns, explosive harpoons and steam-driven whaling boats later that century made large-scale commercial whaling so efficient that many whale species were over-exploited in the 20th century and came very close to extinction.
When southern right whales and blue whales became scarce, Australian whalers began to target humpback whales, killing approximately 8300 off the east coast between 1949 and 1962. By the time the International Whaling Commission banned humpback whaling in the Southern Hemisphere in 1963, over-exploitation had already reduced the population to an estimated 3.5–5% of pre-whaling abundance, leading to the collapse of Australia’s east coast whaling industry. Whalers from the Soviet Union continued to whale illegally throughout much of the Southern Ocean, killing 48 702 humpbacks between 1947 and 1973. More than half of these were taken in the two whaling seasons of 1959–60 and 1960–61.
Whaling in Australia, though mainly targeting sperm whales, continued until 1978, by which time the industry was no longer viable. A change in public attitude against whaling encouraged the Australian Government to hold an Inquiry into whales and whaling in 1979. Following this, the government, with bi-partisan support, adopted a permanent ban on further whaling.
The Whale Protection Act 1980 has now been replaced by the Environment Protection and Biodiversity Conservation Act 1999. The Australian Whale Sanctuary, established under the 1999 Act, includes the entire Commonwealth marine area, beyond the coastal waters of each state and the Northern Territory. Within the sanctuary, it is an offence to kill, capture, injure, harass, chase or herd whales, dolphins and porpoises. The 1999 Act lists humpback whales as vulnerable and state legislation of Victoria, New South Wales and Queensland provides similar protection.
It is estimated that when the Australian east coast whaling industry ended in 1963, the east coast population of humpbacks had been reduced to a little over 100 individuals. Thankfully, this population has shown steady recovery of around 10 –11% a year, and in 2006 was estimated at around 8000.
The recovery of the humpback population has contributed significantly to the rapid growth of Australia’s whale watching industry. The Australian National Guidelines for Whale and Dolphin Watching 2005 have been developed to minimise impacts on whales, dolphins and porpoises and to give people the best opportunity to enjoy and learn about them. Everyone in Australian waters must follow regulations on how to behave around these animals, for example, touching or feeding them is not allowed. Vessels must travel carefully at low speed and stay at least 100 metres away, although a closer look is sometimes possible if curious whales choose to approach the vessel.
Individual humpbacks still face threats — they can become entangled in fishing gear or be struck by ships. Scientific whaling, pollution, climate change, ocean noise and unsustainable tourism may also affect the population. Humpback calves stay with their mothers for 11–12 months before becoming independent. During this time, the biggest threat they face is attack by killer whales or sharks.
Despite our fascination with humpback whales, we still know surprisingly little about them. Where exactly in the Great Barrier Reef do they mate and calve? How much do the east and west coast populations interact with each other in the southern feeding grounds? The Australian Government continues to fund non-lethal research and other activities to promote whale conservation. The more we understand about these animals, the more we are able to recognise their intrinsic value and improve their chances of recovering further from the impacts of whaling.