Although it was able to break the water's surface and breathe, "the whale was likely anchored to that spot, much like a dog tied to a leash," said Scott Landry, head of an agency that rescues entangled marine animals.
"It was just a big, wild animal in a lot of pain, and quite fearful," he said.
Rescuers from groups in Massachusetts and New Jersey joined forces to rescue the whale Friday morning by using a knife at the end of a 30-foot pole to slice through fishing rope that was wrapped around both sides of the whale's tail. It took a while for the wounded animal to realize it was free, but once it did, it swam away quickly.
"I think this whale is likely going to be fine," said Landry, director of the Center for Coastal Studies' Marine Animal Entanglement Response Program in Provincetown, Mass., which responded to a site 2 miles northeast of the Manasquan Inlet to lead the rescue effort.
The whale was injured by the rope cutting into its tail, but those injuries will scar over, Landry said.
"The prognosis for this whale is quite good," he said.
Rescuers from his group, along with the National Oceanic and Atmospheric Association and New Jersey's Marine Mammal Stranding Center used a small inflatable boat to get close enough to the whale to cut the rope line, which had been attached to fishing gear called "high-fliers" like those used on commercial fishing boats.
The agencies are not following or monitoring the whale. They did photograph the distinctive markings it was born with so they can see if it rejoins groups of whales in this area.
Humpback whales are not common off New Jersey, but more of them have been showing up this year, and researchers are unsure why.
Landry said it did not appear the whale had been entangled for very long, which helped save it.
"If it had been much longer, it would have been much different," he said.
Authorities said it is not uncommon for whales to become entangled in objects; 10 to 15 percent of whales show new entanglement scars each year, they said.The National Oceanic and Atmospheric Association, the Center for Coastal Studies in Provincetown, Mass., and New Jersey's Marine Mammal Stranding Center helped free the whale.