A 45-ton humpback whale that became entangled in several hundred feet of heavy fishing line in Hawaiian waters has been set free after a week, officials say.

A boat from the Hawaiian Islands Humpback Whale National Marine Sanctuary managed to get close enough to the marine mammal for the crew to use a long pole with a knife attached to cut the line free, sanctuary workers said.

The heavy gauge crab fishing line had at least five wraps around one of the flukes of the whale, said the National Oceanic and Atmospheric Administration (NOAA), which had helped coordinate the rescue effort.

Such entanglements can lead to drowning, infections, starvation and increased susceptibility to ship strikes, experts said.

The entangled whale had first been spotted Feb. 13 northwest of Hilo, towing a red buoy attached to the fishing line. Responders were able to attach a satellite tag to the animal to track it.

A first rescue attempt was called off when the whale swam into an area of strong, dangerous ocean currents.

When the whale was again spotted off the south shore of Maui, a response team in a rescue vessel was able to approach the animal, attaching more buoys to the trailing fishing line to slow it down and keep it near the surface so the entangled line could be cut away.

All of the line was successfully removed except for a small piece lodged in a wound on the whale's fluke.

That fragment should fall away as the wound heals, said Ed Lyman of the sanctuary, who described the moment of rescue.

"There was no sudden thrashing. It would trumpet blow, which is a sign of stress," he said. "It definitely wasn't happy with us being there. It didn't understand."

Rescuers were able to collect tissue samples from the marine mammal to assess its condition, NOAA officials said.

Humpback whales are found in polar to tropical waters from the Arctic to the Pacific Ocean, and can travel more than 3,000 miles in seasonal migrations.

Humpbacks can live between 45 to 50 years.