Skomal tagged the shark at approximately 11 a.m. in the vicinity of Hadley Harbor, near Naushon Island. He used a six-foot-long spear to attach the device to the shark's dorsal fin.

Skomal said it was the first time a great white shark had been tagged with a satellite device in the Atlantic Ocean.

"It's a spectacular animal," said Skomal. "The most impressive thing is the girth. It probably weighs 2,000 pounds." Skomal said the shark appeared to be healthy, and that he was uncertain of the sex of the animal.

The shark has apparently spent several days in the somewhat enclosed area framed by Woods Hole, Naushon Island, and two smaller islands, Uncatena Island and Nonamesset Island.

Skomal said officials intend to monitor the shark's activities over the next few days, hoping that it will be able to leave the area on its own. "If it sticks around, we may try to figure a way to drive the animal out of the area," he said. "Hopefully it won't come to that."

Skomal said he had been besieged by media calls from around the Northeast, and expressed concern that news of the shark would inspire boaters to flood the area, potentially endangering the shark. "We don't need two dozen boats down there," he said. "The greatest danger is too much attention."

Sidling up to the predator was a thrill, said Skomal, who tagged the 15-foot shark from a 21-foot boat.

"When you're dealing with an animal of that size, you've got to be careful, period," said Skomal. "It's not likely to do any harm, but if something triggered it, watch out."

Skomal, the state's shark expert, sounded thrilled and tired last night.

"I'm the first person to ever tag a white in the Atlantic," he said. "I'm not bragging, I'm just exhilarated. It's a rare opportunity."