The search for a whale in the Bay of Islands with its head bound with rope was called off due to bad weather.

Rough seas yesterday hampered the search for the humpback whale seen on Thursday near Deep Water Cove with a rope tangled around its head.

However, the search would continue today if conditions permit.

Marine mammal expert Floppy Halliday, from Whale Rescue, said a trained team was ready to help free the whale if it was found.

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''We have a team who know the strategy for doing disentanglements and we are prepared to go through the procedure,'' she said.

''It takes time. We just hope the whale has time.''

Thought to be a young adult male, the whale was seen with the crayfish rope wound around its head and clamping its mouth shut near Deep Water Cove on Thursday.

Halliday said it was last seen about 5pm that day, by which time it was having trouble holding its head up to breathe properly.

Its behaviour indicated the craypot was still attached to the rope, possibly stuck on the seabed, and was weighing the whale down.

Despite yesterday's rough, windy conditions which steadily worsened through the day, Halliday said search boats and a helicopter with Department of Conservation staff aboard covered a wide area in the morning.

The rope entanglement has stopped the humpback whale from moving freely, but it can still breathe. Photo / DoC
The rope entanglement has stopped the humpback whale from moving freely, but it can still breathe. Photo / DoC

A concentrated search around the inner Bay of Islands had expanded out to sea before the weather forced the search to be called off.

Halliday said it was likely the whale was a sub-adult male because this is the time of year they cruise around Northland's coast.

The message for boaties was to report any sightings of the whale but not to get close to it, she said.

Sightings should be reported as soon as possible to Department of Conservation's emergency line 0800 DOC HOT or Whale Rescue, 0800SAVEWHALE.

There have been several successful rescues of whales and dolphins caught in ropes or plastic twine, and many sightings of distressed marine creatures around New Zealand's coast which could not be saved.

In 2010 in Northland, a 7m humpback was successfully freed after a two-day operation at Doubtless Bay.

Two years later, a 19-year-old diver cut the rope of a crayfish pot entangled around an orca several hundred metres off the eastern Coromandel coast.

New Zealand's winter and early spring was the whale's peak migration time and in the past month there have been several humpback whale sightings in the region.

Early last month an adult female humpback and a calf died after stranding on Baylys Beach, south of Dargaville, and a week later another humpback was spotted in Whangārei Harbour.