A dead humpback whale calf was found at the weekend at the Port of Brisbane.
© Brisbane River Fishing/FacebookA dead humpback whale calf was found at the weekend at the Port of Brisbane.
Authorities have no idea what killed a humpback whale calf found floating in the Port of Brisbane at the weekend.

A dead male humpback calf was spotted floating upside down near the mouth of the Brisbane River about 11.40pm on Saturday night by Alex Donaldson and his friend who were on their way out to go sea fishing.

Mr Donaldson, who fishes a few times a week, said he first thought the calf was a bit of floating rubbish.

"I thought it was a big bit of garbage floating down the river," he said.

"Every week we go out, we usually see a dead turtle so we thought it could be one of them.

"There were quite a few sharks below it, but they weren't coming up to it."

Mr Donaldson said the whale didn't smell and he figured it had not been dead long.

"It's not that shocking, it's a bit of a dump at Moreton Bay."

Mr Donaldson and his friend left the calf and about an hour later Megan Williamson, another recreational fisher, spotted the 4.5-metre whale bobbing on the surface.

Ms Williamson had been out fishing with her partner and three of his friends about 12.30am when they came across the carcass.

"We thought it was a bit of rubber that had come off from the port, it was right beside the port, but as we got closer we saw it was an upturned baby whale," she said.

"We went up to it and I said, 'no that can't be what it is'.

"You don't expect to see something like that, it was very confronting, especially when it is in the river.

"When we were there, it was sitting a few metres off the edge of the port, where the container ships pull up.

"We stayed there for 20 minutes away from it, we could see it was drifting around."

Ms Williamson contacted Fisheries Queensland and was told they were aware of the situation and were dealing with it.

A statement from Queensland Parks and Wildlife Service said staff responded to a report of a dead whale at Fisherman Island in the Port of Brisbane on Monday.

"The whale was a male humpback calf about 4.4 metres long and had been dead for about five days," the statement read.

"QPWS staff towed the whale carcass to Mud Island for disposal on the island on Tuesday morning.

"The cause of death is not known, as the carcass was too significantly damaged by the time it was retrieved."

QPWS reminded skippers to slow down and keep an eye out as humpback migration continued along the Queensland coastline.

"As the humpback population increases we can expect to see an increase in the number of whale strandings," the statement read.

"Humpbacks and other whales sometimes move through Moreton Bay.

"Skippers are reminded to slow down and keep a watch out."