The unusual movements of an entangled humpback whale off the coast of New South Wales have been a cause of concern for rescue teams, who have lost sight of the mammal due to rough weather conditions.

The Organisation for the Rescue and Research of Cetaceans in Australia (ORRCA) first reported a sighting of the whale north of Cape Byron, in northern New South Wales, on Wednesday morning.

The humpback was trailing a rope with a coloured buoy from its left fin. 

Crews were able to cut a small portion of rope tangled around the whale the following day, but were hindered by “extremely difficult conditions” and “challenging seascape”. 

ORRCA initially believed the whale would continue to travel north off the coast of south-east Queensland, but it has instead travelled down the coast of New South Wales.

The whale is believed to have passed Sydney over the weekend and is expected to be somewhere between Port Kembla and Culburra Beach, south of Wollongong, today.

“The whale is currently tracking south, which is not typical for a humpback whale at this time of year,” ORRCA spokesperson Pip Jacobs said.

“They would usually be making their way north as part of the northern migration.”

South coast residents are urged to be on the lookout and report any sightings as the whale is expected to reach south to Ulladulla, east of Canberra, this evening.

“We currently have not had any further confirmed sightings of the whale today along the south coast,” ORRCA spokesperson Pip Jacobs said.

“We estimate that it may be around Ulladulla around sunset, however it is difficult to predict without additional sightings today.

“Conditions on the water are extremely windy, which is making efforts to locate the whale challenging.”

ORRCA and the public are out trying to find the whale along the south coast.

If a sighting is confirmed, crews are ready to assess the possibility of a disentanglement operation.