KEY POINTS:
A humpback whale entangled in crayfishing gear may soon be in sight of the North Island and the Department of Conservation is urging people to report sightings so a rescue can get under way.
DoC was told on Friday that the whale had been spotted off Kaikoura in a distressed condition.
Staff went to free the whale but were thwarted by a rough sea and, when they returned the next morning, there was no sight of the mammal.
It is believed to have headed north up the east coast towards the North Island, which is part of the species' migrating pattern at this time of the year.
"If still entangled, the whale is unlikely to be in any immediate risk of drowning but the rope would likely be causing distress and could also cause injuries," said DoC spokesman Dave Hayes.
"It is also likely to impede the whale's movement and its ability to feed. The rope was made of sisal [plant matter] so in time it would rot away but we would like to get it off the whale now to avoid further harm."
The brightly coloured buoys attached to the rope were likely to alert people. It was unclear if the craypot was still attached to the whale or if it had broken off.
"We urge people not to make any attempt to disentangle the whale themselves as it is dangerous," Mr Hayes said.
"People should contact us and we will assess the situation and conditions at the time and endeavour to cut the whale free if we can."
DoC had developed a procedure and specialist equipment for freeing entangled whales based on techniques used by similar agencies in Australia and the United States.
Mr Hayes said the procedure could take several hours and could be carried out only in daylight.
DoC staff used the technique for the first time last July on another humpback whale that was also entangled in rope and trailing a craypot off Kaikoura.
Conservation workers were not able to cut the whale free from the rope before having to abandon the attempt because of the impending darkness, and the whale was not seen again.
Since 2001, there have been eight cases of whales becoming entangled off Kaikoura. Their inquisitive nature is believed to contribute to the problem.
Anyone who spots the entangled whale is urged to call the DoC hotline, 0800-362-468.
