Rescuers said their odds of freeing the 40-foot whale from the life-threatening entanglement were about 50-50.
The whale was first spotted Wednesday about 15 miles offshore from Brunswick, Ga., by researchers who monitor North Atlantic right whales during the winter calving season.
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A Georgia Department of Natural Resources crew managed to cut away several of the fishing lines by snaring them with grappling hooks and dragging them into a boat. They also attached a tracking buoy to monitor the whale's movement.
By Friday morning, the whale had moved off Daytona Beach, Fla., where poor weather prevented further attempts to free it, said Patricia Naessig, right whale aerial survey coordinator for the Wildlife Trust, an international conservation group that tracks right whales in the southern U.S.
She said Sunday might be the soonest seas would be calm enough for another attempt.
"We are concerned if something isn't done for this whale, its health condition could deteriorate over time," Naessig said.
Naessig said the whale still had fishing line caught in its mouth and was dragging three lines 50 to 80 feet behind it. She said the lines were cutting into the top of the whale's head and the base of its tail.
Researchers believe only about 300 North Atlantic right whales remain in existence. They spend most of the year off the coast of the northeastern U.S., but migrate to warmer waters off Georgia and Florida each winter to birth their calves.
Whale entanglement experts with the National Oceanic and Atmospheric Administration and the Provincetown Center for Coastal Studies in Massachusetts were discussing Friday the safest ways to try to free the whale.
Jamison Smith, NOAA's East Coast project leader for whale disentanglement, said the success rate for freeing right whales from fishing gear is about 50 percent.
"It's very dangerous, both for the whales and the people responding," Smith said. "This animal's in better shape than it was on Wednesday because it doesn't have as much drag pulling on it. But the entanglement is fairly severe."