"X-rays did not reveal where the hook is lodged," said Dolores Clark, a spokesperson with the National Oceanic and Atmospheric Administration. "But the fishing line was extending out of its mouth, so it is presumed there is a hook in there."

The seal was taken to the Kane'ohe Marine Corps Air Station laboratory for the procedure this morning. A seal specialist from California was to consult with local veterinarians and examine the 500-pound male monk seal. At least four veterinarians will perform the surgery, said Dr. Marty Haulena, a seal specialist from the Marine Mammal Center in Sausalito, Calif.

Haulena said the veterinarians will anesthetize the seal and feed an endoscope — a tiny camera mounted on a flexible tube — into the seal's mouth and down his throat. If they find the fish hook, veterinarians can remove it using tiny instruments controlled through the tube.

Then the vets will do a lot of watching and waiting to see how the seal recovers. Haulena said infection is the most dangerous threat to the seal's survival.

"It could be less than a week, it could be a month before the seal is released," he said. "If the animal is able to eat on his own it would be a good sign."

He said the monk seal's normal eating habits could be thrown off, however, because it is not used to living in captivity.

A second injured monk seal sighted near Po'ipu on Kaua'i's south shore last week was seen over the weekend without a fish hook that reportedly was protruding from its mouth, said Clark of NOAA.

"He apparently disentangled himself and went on his merry way," she said. Wildlife experts are still observing the seal.

A third injured monk seal was reported off Mokule'ia, O'ahu late last week by a Camp Erdman counselor, Clark said.

Fish and wildlife experts looked for the seal over the weekend but didn't find it, said Thea Johanos, a wildlife biologist at the National Marine Fisheries Service branch of NOAA.