Members of Orrca (the Organisation for the Rescue and Research of Cetaceans in Australia) are on site and a vet is en route to assist but the chances of saving the mammal are not good, she said.

"It's not where it needs to be but we're doing the best we can," she said.

"It's being knocked about."

As a sub-adult, it may be the first time this humpback has made the migration northward, and there have been some big seas, she said.

Up to 30,000 whales are thought to be migrating north this season, which is great, but unfortunately some don't make it, the department's spokeswoman said.