A humpback whale missing its tail has been spotted off Kaikoura.

Department of Conservation (DoC) Kaikoura ranger Mike Morrissey went out by boat to check on the whale on Monday afternoon after a reported sighting.

The whale's tail flukes were missing, but it appeared relaxed and was moving well.

He estimated the whale was about two or three years old. The wounds where the flukes had severed from its tail had healed, indicating they were lost some time ago.

"What was left of the whale's tail was tapered like an arrow tip. It's bewildering as to how it came to lose both its tail flukes," Mr Morrissey says.

"Fortunately, the whale wasn't showing any signs of distress. It was swimming well and breaching, diving and rolling as humpback whales typically do."

DoC says the tail was severed some time ago (Viraj Gamage)

The whale was seen off Kaikoura again yesterday.

The flukes could have been severed by the whale getting badly entangled in rope, but Mr Morrissey couldn't be sure. There have been occasional reports of other whales with damaged tails.

DoC is asking boaties to take particular care not to disturb the whale and keep their distance to protect its welfare, given its severe injury. Boats must be kept at least 50 metres away from marine mammals.

Humpback whales travel through New Zealand waters as they migrate between summer Antarctic feeding grounds and winter south Pacific breeding grounds. It is thought the whale will move north from Kaikoura as humpback whales start their annual migration.

A normal Humpback whale tail (DOC Cook Strait Whale Survey)

Anyone who spots the whale without a tail as it travels up the coast should tell DoC so its movements can be tracked. Calls can be made to DoC's 24-hour hotline -- 0800 36 24 68.

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