A crew member of a Korean coal transport ship was presumed dead by falling overboard.
The man was noticed missing, and a search of the vessel K Pride was carried out with an incident recorded on May 14, but unions were not informed until Monday night.
The ship was en-route to the port of Newcastle.
International Transport Federation co-ordinator Dean Summers said the incidence of people falling from ships or jumping overboard was on the increase.
"It's another disaster in a long line of disasters and as I have been saying for a long time we have seen a spike in people being lost over the side and reported suicides," he said.
"This time it looks like a man just wasn't noticed around the place and so his co-worker notified the captain and so they turned the ship around but they were looking for a few days and just haven't found him."
Korean owner of the vessel SK shipping said there would be an investigation, and told the ABC it would involve the Australian Police, however Australian Federal Police referred the ABC to NSW Police.