very year from late April to August, humpback whales migrate north along Australia’s Pacific coast to the warm coastal waters of Queensland and the Coral Sea to mate and give birth. According to Geoffrey Ross, wildlife management officer and coordinator of the Marine Fauna Program for the NSW National Parks and Wildlife Service (NPWS) off Cape Solander south of Botany Bay, humpback whale migration periods are becoming longer annually as their numbers increase.

“Roughly by 2017 we will be seeing twice the number of whales passing Cape Solander than we saw in 2009,” said Ross. “We are seeing whales that leave early leaving earlier, and whales that leave late leaving later, so we will see whales over more of the year. Triggers such as day length and water temperature do effect the humpback migration, but there are a lot of variables involved that unfortunately, the whales have no control over.

Dramatic rebound

Since Australia banned whaling in 1979 humpback numbers have rebounded dramatically. “We are seeing numbers at 16-18,000 over a season, which is down from the pre-whaling days of 36-40,000, which means we have about half of the expected numbers off the east coast,” said Ross said.

Ecologist Dr. Peter Gill from the charitable organization Blue Whale Study has also noted recent migration changes, in both blue whales and humpbacks. “This [last year] is the earliest we have ever seen blue whales arrive in the Bonney Upwelling, and it is the first time I have seen humpbacks hanging around feeding," said Gill.

“One reason that the timing might be changing could simply be that there are now so many more humpbacks than there were even 10 years ago, because when I started humpback research on the NSW coast in the early ‘80s there were probably fewer than 1000 migrating whales, now there are 20 times that,” he added. However, Ross said the same cannot be said for the southern right whale, which is recovering more slowly due to the whaling pressures of the past and their calves also being subject to vessel strikes