Seven healthy, endangered female Hawaiian monk seals are on Oahu preparing for their journey back to the wild.

Staff at The Marine Mammal Center’s hospital in Kailua-Kona for Hawaiian monk seals — Ke Kai Ola — have since September tended to six underweight pups that were weaned too early and abandoned by their mothers, and one yearling that was malnourished.

The monk seals brought to Oahu on Thursday were the largest number to be moved from the hospital all at once. It was made possible through collaboration by the U.S. Coast Guard, the National Oceanic and Atmospheric Administration and Ke Kai Ola (The Healing Sea), said Eric Roberts, marine mammal response coordinator of the Coast Guard’s 14th District.

Only one or two seals had previously been transported back to the wild at the same time.

The effort between the agencies took a lot of planning to ensure a seamless transition, he said. “It was perfectly executed in this case.”

“The Coast Guard, we like to pride ourselves in being lifesavers. This is kind of those unique areas where we actually can help save the lives of a species instead of just an individual, so this is really a proud moment for our Coast Guard men and women,” said Roberts at the Barbers Point Coast Guard Air Station.

The Coast Guard’s C-130 Hercules airplane arrived at the air station with the seals at approximately 11:20 a.m. Thursday. David Schofield, NOAA’s Marine Mammal Health and Response coordinator, and his team carefully unloaded the seals in large metal cages onto four trucks.

A convoy headed to the NOAA Inouye Regional Center at Ford Island, where the seals will be under veterinary care for 48 hours. From there they will be taken to the NOAA research vessel Hi’ialakai for their return to the wild.

Within the next week or so, six of the seals will be returned to the Northwestern Hawaiian Islands. Three — Mahina, Mo‘o and Ama‘ama — will be transported back to the French Frigate Shoals; two — Neva and Puka — will go back to Lisianski Island; and one — ‘Ena‘ena — will be taken to Kure Atoll. The seventh seal, Kilo, will be returned to Niihau.

The NOAA research vessel Oscar Elton Sette transported the ill seals to Ke Kai Ola in September. They weighed from approximately 40 to 80 pounds upon arrival.

In a phone interview from Sausalito, Calif., Dr. Shawn Johnson, head veterinarian of The Marine Mammal Center, said: “They were so thin and emaciated. We were so fortunate to save them and get them back out.

“We feel it’s a necessary part of the Hawaiian monk seal recovery plan to rescue and rehabilitate these females, that they would not have survived through the winter without our intervention,” he added.

Staff at Ke Kai Ola fed them “fish milkshakes” — ground fish mixed with oil and water. Some had to be tube-fed because they were too ill to eat on their own. Each recovered seal weighed over 200 pounds upon release from the monk seal hospital.

Rehabilitating female Hawaiian monk seals is vital to the survival of the endangered population. There are approximately 1,200 monk seals, a majority of which are at the Northwestern Hawaiians Islands and approximately 200 in the main Hawaiian Islands.

When the monk seals reach the Northwestern Hawaiian Islands and Niihau, Roberts said, biologists will attempt to tag the seals to monitor their movement.

Ke Kai Ola was established in 2014, and to date has rehabilitated 15 Hawaiian monk seals, representing a little over 1 percent of the endangered population, said Johnson.