The first Hawaiian monk seal successfully raised from birth in captivity was diagnosed with cataracts after being plucked from Kaunakakai Harbor on Friday, which means he won't be going back to the wild.

It's rare to see cataracts in a seal so young.

At under 2 years old, the seal — called KP2 — is still considered an adolescent.

The disappointing development, announced yesterday by the National Oceanic and Atmospheric Administration, comes as scientists are scrambling to learn more about the endangered Hawaiian monk seal in hopes of stabilizing the population. Today, there are only 1,100 of the seals in the wild. And the population is declining by 4 percent annually.

The population would have to be at 2,900 seals for 20 years to be taken off the endangered species list.

"Every individual is important to the population," said David Schofield, NOAA marine mammal response coordinator.

Schofield said it's believed KP2 developed cataracts at a young age because he missed out on mother's milk.

So far, Schofield said, scientists have been unable to create a formula that matches the richness of natural seal milk.

KP2 will spend the rest of his life in captivity. Hawaiian monk seals live to be about 25 to 30 years old.

"He will likely spend the rest of his days," Schofield said, "as an ambassador for monk seals."

Schofield added that KP2 taught scientists a lot about Hawaiian monk seal pup development.

"Everything from diet, nutrition, behavior, I think we learned a lot from this critter," he said.

KP2 was picked up by NOAA in May 2008, after being abandoned by its mother on Kauai.

The pup spent about seven months in rehabilitation before it was released off Kalaupapa, Molokai. NOAA scientists said KP2 was doing fine in the wild for months, but in March it discovered Kaunakakai Harbor. That's when it started interacting with humans.

NOAA spearheaded outreach efforts and public meetings to warn people to stay away from KP2 so that he wouldn't get used to being around humans. And, NOAA officials said, people listened.

But by that time, KP2 was already used to human interaction.

He liked to jump up on surfboards, sun on outriggers and play with kids.

His antics even got him national attention, with spotlights on the "CBS Evening News" and in the Wall Street Journal.

But lately, as KP2 grew into a teenager, cute play turned into aggressive roughhousing.

From July to September, complaints about KP2 mounted. He nipped at swimmers and held them underwater.

In mid-September, he bit a swimmer in a wetsuit, causing a contusion on the swimmer's leg, NOAA said.

It was that behavior that spurred NOAA to decide it was time for KP2 to be moved.

On Friday, NOAA caught KP2 in Kaunakakai Harbor and the Coast Guard flew him to Honolulu for some tests.

He was then going to be re-released in a more remote area of the Hawaiian Islands.

But a check-up at the Waikiki Aquarium showed KP2 had developed cataracts. He is now 80 percent blind.

Andrew Rossiter, aquarium director, said yesterday that the saga of KP2 has been instructive.

"We haven't got it perfect," he said, referring to rehabilitating monk seal pups for the wild.

He added, "It's a very good first step."

He suspects KP2 will not be the last monk seal to be raised in captivity and released in the wild.

"Efforts like this are going to be critical" as the population continues to drop, he said.

KP2 is currently at the Waikiki Aquarium, where he'll be in the interim until a permanent home can be found for him.

Schofield said Sea Life Park may accommodate the seal, or he may be moved to the Mainland.

The seal will have to undergo surgery for his cataracts, without which he would go blind in six months.

Even with the surgery, he couldn't be re-released into the wild because he would be too used to captivity.