An aggressive Hawaiian monk seal named KE 18, known for attacking pups and juvenile seals in the Northwestern Hawaiian Islands, has been removed from the wild by scientists.

More than a dozen attacks by the male monk seal forced federal wildlife officials to act. Biologist Chad Yoshinaga and his crew went to Midway Island last weekend on a mission to remove the 450-pound seal from the wild.

"He is very strong. He did put up a decent fight while we were trying to get him into captivity," Yoshinaga said.

Crews carefully caught KE 18 and sedated him with valium. The 9-year-old seal was placed in an outdoor cage for about nine hours before being flown over to Honolulu on Monday. KE 18 is staying temporarily at the Waikiki Aquarium, and officials said he is adjusting nicely.

Dr. Charles Littnan, lead scientist of the National Oceanic and Atmospheric Administration Monk Seal Research Program, said KE 18's aggressive behavior in the wild is not uncommon, but what causes such behavior is still unknown.

"KE 18, if you look at him, he has a lot of punctures that are indicative perhaps of being a victim of a male aggressor himself," Littnan said.

Dr. Littnan said the plan is to relocate KE 18 to a marine lab at the University of California Santa Cruz for two years. His aggressive behavior will be studied, and scientists can also gather research vital to monk seal conservation efforts

After KE18's two-year stay, NOAA officials plan to move him to what they hope will be his final home, Oahu's Sea Life Park. He will not be released into the wild.

"KE 18 was a threat, identified to have killed pups. He cannot be returned to the wild without risking future generations of seals," Littnan said.

NOAA says euthanizing KE 18 is still an option if the current plan fails.