WHAT killed this apex predator still remains a mystery.
The blue shark washed up on Byron Bay Main Beach on Friday morning.
Southern Cross University shark expert Dr Daniel Bucher conducted an autopsy on the creature to try to determine the cause of death.
He said its proximity to the coast was unusual, given the species generally sticks to open oceans where the water is cooler and deeper.
Initially, Dr Bucher said swallowing a long-line hook, plastic in the gut or pregnancy complications may have caused the shark to become ill.
However, after examination, he said there was no obvious cause of death, although the shark's stomach and intestines were completely empty, meaning it hadn't eaten in a few weeks.
Fin and flesh samples have been taken to determine the shark's metal content and its vertebrae have been examined to work out its age.
"At this stage, we really don't know how long they live for," Dr Bucher said.
"We know that other species of sharks can range from 20 to 50 years old so what we'll do is remove a couple of vertebrae from the spine, just behind the skull, and they have growth rings in them, like the growth rings on trees so you can make a bit of an estimate on the age."
Samples will also be taken for teaching purposes and the dissection filmed.
Dr Bucher said samples from the dissection would help contribute to shark metal contamination research being undertaken at the university.
"This one's an interesting one because the species we've looked at so far for that work have been coastal species that tend to have a higher exposure to metal contamination," he said.
"This one is an open-ocean fish, so this might give some good baseline to compare those coastal ones with."
Dr Bucher said it was highly unlikely any human remains would be found during the dissection.
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