Marine experts cut loose a yearling humpback whale yesterday that had been entangled in heavy plastic rope near the Hawaiian Islands.

“;We saved this whale,”; said Ed Lyman, marine mammal response manager for the Hawaiian Islands Humpback Whale National Marine Sanctuary. “;It's in good shape.”;

The rescue effort began five days earlier when a whale-watching tour spotted the whale caught up in 400 to 500 feet of rope about three miles off Maui. Bad weather continually frustrated freeing it.

The rope, which threatened the animal's life, ran through the whale's mouth, around its head and twisted into a knot.

Rescuers noticed a small window of opportunity on Saturday when a tracking buoy attached to the rope showed the whale was finally slowing, and weather forecasts predicted calm seas in the area.

“;We had to get all our ducks in a row,”; Lyman said. “;We were patient.”;

At about 7:30 a.m. yesterday, scientists departed on a 47-foot Coast Guard motor vessel, searching about two hours for the 30- to 35-foot animal.

When the whale was spotted, it was about 25 miles south of Oahu. Experts began a five-hour effort to free the whale using a technique modified from one that whalers used to kill the animals a century ago.

Lyman said they attached three plastic air-filled buoys to the rope on the whale, trying to slow the animal as whalers would by harpooning marine mammals.

Even while pulling the buoys, the calf still traveled at 5 knots—too fast for an attempt to cut the rope.

The crew then attached a sea anchor, a device like a parachute underwater. The whale finally slowed and began staying near the surface.

Lyman said they hooked a knife to the rope near the whale's back using a long pole, needling the blade between the rope and a cleft left by a wound from the rope. The knife was then attached to another sea anchor, and after 10 minutes it sliced through the rope.

“;All of a sudden the lines just stopped and the whale disappeared,”; Lyman said. “;We got every single piece of line off that whale.”;

The rescuers freed the calf without separating it from its mother and a male escort. All three swam off, the young with wounds mostly from chafing by the rope.

The Coast Guard spotted the whale and confirmed all the rope came off, Lyman said.

He did not know where the rope, which was later recovered, came from because it did not have any markings.

It was the first whale to be rescued from tangled marine gear this season in Hawaii. Two whales were rescued last season, including one that was entangled in shrimp gear dragged thousands of miles from Alaska.

About 10,000 humpback whales travel to Hawaii every winter to mate, calve and nurse their young. The whales are an endangered species.