A member of the public called rescue organisation ORRCA about 9.30am on Thursday, March 21 after coming across the calf on Perkins Beach.

The caller reported the calf was still alive and moving, but ORRCA vice president Steve Trikoulis said it appeared to have died by the time rescuers arrived.

The body was moved off-site to the Whytes Gully tip, where Taronga, the NSW National Parks and Wildlife Service (NPWS) and ORRCA performed a necropsy on Thursday afternoon.

A NPWS spokesperson said the post-mortem did not reveal any obvious cause of death, and the calf was "in good body condition with evidence that it had recently been nursing from its mother".

"Sperm whale strandings are a rare event and the samples collected from the post mortem will help build our understanding of the threats facing these animals," the spokesperson said.

Mr Trikoulis said it could take some time, possibly months, before the results of the necropsy were available.

He said that while the calf had cookiecutter shark bites, these were common on marine animals and there were no obvious external injuries contributing to its death.

The calf was "probably a month old, at best", Mr Trikoulis said, measuring 3.4 metres long.

The Illawarra Local Aboriginal Land Council was also in attendance.

Attending such events was sad for rescuers, Mr Trikoulis said, but ORRCA held a debrief in the days afterwards to check in with everyone involved.

Anyone who sees a whale, dolphin, seal or dugong in distress is urged to contact ORRCA on 9415 3333.