RELATED CONTENT: Whale washes ashore in Batemans Bay: photos
Whale scientist Geoff Ross has warned swimmers to avoid Batemans Bay's North Head beach, where an eight-metre dead whale washed ashore at the weekend.
The National Parks and Wildlife Service scientist said sharks, including bull sharks and great whites, would be drawn to the young humpback's carcass.
The whale washed ashore mid-afternoon on the northern shore of the bay, near Yellow Rock, on Saturday.
By Sunday it was considerably bloated and beginning to smell and a camper who discovered it said he had already seen what he thought was a small shark.
"Whale carcasses attract sharks," Mr Ross warned.
"I would recommend swimmers avoid the area.
"Bull sharks would be attracted out of the Clyde River, to the entrance.
"They are nature's cleaners.
"Their job is to remove carcasses and they do it well, but you don't want to get in their way.
"Great white sharks will be attracted to whale carcasses too."
Mr Ross, who leaves Sydney tomorrow on a five-day whale counting voyage to Eden, said the photographs showed what was probably a juvenile humpback whale.
"It seems to be a yearling, or at least a couple of years old," he said.
"It is not an adult, but it is not one of this year's calves either.
"It is most likely female."
Mr Ross said the whale, whose back is not visible in any pictures taken on Saturday or Sunday, could have been struck by a boat propellor.
However he said the pictures showed no clear cause of death and it may also have succumbed to a chest infection or a virus, or fallen victim to killer whales.
"Without seeing the whole carcass, it is hard to say," he said.
Mr Ross said the carcass was "best left to degrade naturally".
"We should probably let the marine organisms do the job they are so good at," he said.
Mr Ross said up to 15,000 whales were now travelling down Australia's eastern coast to Antarctica, after wintering and breeding as far north as the Coral Sea and Tonga.
He said even dead whales helped scientists understand their secrets.
"It is really helpful," he said.
"We like to look at all dead, stranded or beach-washed cetaceans," he said.
"Even dead animals are terribly important.
"A lot of our knowledge comes from measuring and taking samples.
"DNA samples can tell us about relationships and in the long term, you have a list of the relationships."