The whale was spotted by a University of Otago lecturer and students off the Karitane coast last Thursday, wrapped in a line and trailing a buoy, while moving slowly north.
On Wednesday it was reported close to the Kaikoura coast by Whale Watch Kaikoura staff.
Doc's large whale disentanglement team then spent three hours working to free the whale, before removing the last of the rope about 7pm yesterday.
Doc ranger Mike Morrissey said the rope "was tightly wound around its tail, leaving extensive and deep cuts, but they should heal".
Grapnel hooks were used to attach rope and floats to material entangling a whale, to slow it down and tire it out.
Once the whale was exhausted, the disentanglement team edged along the rope until they were close enough to reach over with a long pole and knife blades to cut away the material entangling the whale.
The whale had become "very agitated and active" while the team worked, highlighting why such efforts should be left to trained and experienced disentanglement teams, he said.
"The whale was thrashing about, rolling, and tail slapping and you have to know what you are doing. If you didn't have experience and know what to expect it would be dangerous and people could get harmed."
The whale calmed down once the last of the rope was cut from it, and was expected to continue moving north on the annual migration to tropical waters, he said.
