Having spent hours snoozing by the pools in their pens at Ke Kai Ola, the monk seal hospital in Kailua-Kona, Pearl and Hermes were as content as two seals could be.

The two prematurely weaned Hawaiian monk seal pups were picked up by the National Oceanic and Atmospheric Administration monk seal research team in the Northwestern Hawaiian Islands in late May. Over three months they almost doubled their weight on a diet of herring and other fish — Pearl weighing in at nearly 135 pounds and Hermes at 156 pounds.

In an HC-130 Hercules airplane Thursday, Coast Guard crews helped move the pair to NOAA’s Ford Island facility from Ke Kai Ola. NOAA expects to transport them back to Pearl and Hermes Atoll, where they were found and for which they were named, in the next few weeks.

“They are all healthy, so they’re ready to go,” said Deb Wickham, Ke Kai Ola’s hospital operations manager. “They’re very strong, very active.”

The pups now have silvery fur coats, which replaced the shiny black ones they had when admitted to the monk seal hospital at 3 weeks old.

NOAA and Ke Kai Ola work together to save malnourished pups that would otherwise not survive in the Northwestern Hawaiian Islands, which are covered by the Papahanaumokuakea Marine National Monument. Pearl and Hermes are the seventh and eighth seals from the isles to be nursed back to health at Ke Kai Ola, which means “the healing sea.”

“Juvenile survival has been one of the major challenges for most seals (in the NWHI) for a long time,” said Rachel Sprague, NOAA Hawaiian monk seal recovery coordinator. “For a long time our biologists have had to turn their back and walk away from a seal they knew was going to die. Now they have a place to go.”

There are fewer than 1,100 Hawaiian monk seals in the wild, with their population in decline. The seals, found only in Hawaii, were nearly hunted to extinction in the mid-1800s. The seal is now an endangered species protected by federal and state laws.

While seals at Papa- hanaumokuakea continue to struggle with predators and starvation, the population of monk seals living in the main Hawaiian Islands, now at about 200, is experiencing steady growth due to new births here.

Last month NOAA published a plan on how to manage seals in the main Hawaiian Islands that calls for bumping up the population here to 500, with more education and outreach programs and better relationships with fishing communities.

Upon their return to the atoll, Pearl and Hermes will be further protected by an expansion of the critical habitat for Hawaiian monk seals by an additional 7,000 miles, which NOAA announced Aug. 18. The protected areas extend to greater depths of the ocean at Papahanaumokuakea as well as preferred pupping and marine foraging areas in the main Hawaiian Islands.

Saving a few, young female seals has ripple effects for the species, according to Sprague, because they later give birth to new pups. Ke Kai Ola provides an option for seals that need long-term care.

“It has changed the decisions we make in the field about how much we can help certain animals,” she said. “It’s shown how much can be accomplished when you’ve got partners.”

The Marine Mammal Center, a California nonprofit, raised the funds and built Ke Kai Ola in Kona last year at a cost of $3.2 million. The center selected a site at the Natural Energy Laboratory of Hawaii Authority for its proximity to a harbor, airport and access to seawater filtration.

It received its first patients — Kulia, Ikaika, Hala‘i and Maka‘ala — last summer. The first four pups stayed for only two months. In September 2014 two malnourished female pups, Meleana and Pua, stayed at the hospital for six months before their return to Kure Atoll.

When Pearl and Hermes first arrived at Ke Kai Ola aboard the NOAA ship Hi‘ialakai, Pearl weighed just 73 pounds and Hermes weighed 88 pounds. They were initially tube-fed before moving on to fish.

“They started eating a lot sooner than pups in the past,” said Wickham, the operations manager. “When they started eating fish, that was my reward.”

The hospital is equipped with a kitchen, treatment room and four pool pens beneath an expansive, arched canopy. Wickham’s office has a monitor on which she can watch the pups as they sleep, frolic and swim. There’s also a viewing room with a one-way window.

She and about 25 active volunteers try to minimize human interaction with the seals as much as possible.

When Pearl and Hermes first arrived, Wickham said, the two were inseparable. She described them as gregarious and playful. In one photo Hermes keeps Pearl at bay with his flipper while going for a fish. She is glad the pair will be released together at the atoll where they were found.

“We look forward to getting them back home and being able to take care of the next ones,” she said.