A seven-month-old Hawaiian monk seal — rescued after his mother abandoned him less than one day after he was born on Kaua'i — is thriving as it adjusts to the wild.

The Coast Guard last week took the seal, which now weighs 150 pounds, by helicopter to a secret location in the main Hawaiian Islands, where other monk seals live.

When scientists brought him to the water's edge and opened the cage, the pup immediately took off into the water and didn't look back.

It has so far successfully adapted to the wild, said David Schofield, marine mammal response coordinator for the National Marine Fisheries Service.

"Thinking back on how small and scrawny that little seal was, a little bag of bones, and then seeing it fat and healthy and on its way out to the wild, it's just the best feeling in the world," Schofield said Tuesday.

Hawaiian monk seals are an endangered species. Only about 1,100 to 1,200 exist and their population is declining about 4 percent each year.