Marine experts estimate about 40,000 humpback whales are now migrating through Australian waters annually, up from about 1,500 half a century ago.
The humpbacks’ annual journey from Antarctica to subtropical waters along Australia’s east and west coasts is one of nature’s great migrations.
It is a journey of up to 10,000 kilometers and is undertaken between April and November. Scientists have estimated 40,000 humpback whales have been in Australian waters to mate and breed. It is a remarkable recovery from the height of commercial whaling in the early 1960s when it was estimated there were fewer than 1,500 humpbacks. They were slaughtered mainly for their oil and baleen, or “whalebone."
Australia’s environment department says no other whale species has recovered as strongly as the humpback since the end of commercial hunting, which ceased in Australia in 1978.
Australia is now considering removing humpback whales from the endangered species list because of their growing numbers.
The acrobatic humpbacks that can grow to 16 meters would still be protected in Australia. Conservationists, though, argue that they need more, not fewer, environmental safeguards to monitor the impact of climate change on krill - their main source of food. Krill are affected by the absorption of more carbon dioxide into the ocean.
Olaf Meynecke, a research fellow in Marine Science at Queensland’s Griffith University, says vigilance is needed to ensure the whales continue to thrive.
“Generally speaking, yes, it is a great success story that humpback whales have come back. But obviously we also need to ask questions as [to] how will this continue in the future, how are present threats already impacting the population and how we [are] going to detect changes in the future,” Meynecke said.
Scientists say humpbacks face a combination of other threats including the overharvesting of krill, pollution, habitat degradation, and entanglement in fishing nets. Calves also face attack by killer whales or sharks.
The recovery of the humpback has helped the rapid growth of Australia’s whale-watching industry.
As their numbers have grown, much about the humpback, a species famous for its song, remains a mystery. Scientists do not know exactly, for example, where on Australia’s Great Barrier Reef they mate and calve.
Humpback whales live in all the world’s oceans. They take their common name from a distinctive hump on the whale’s back.